| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| In the Linux kernel, the following vulnerability has been resolved:
gfs2: add some missing log locking
Function gfs2_logd() calls the log flushing functions gfs2_ail1_start(),
gfs2_ail1_wait(), and gfs2_ail1_empty() without holding sdp->sd_log_flush_lock,
but these functions require exclusion against concurrent transactions.
To fix that, add a non-locking __gfs2_log_flush() function. Then, in
gfs2_logd(), take sdp->sd_log_flush_lock before calling the above mentioned log
flushing functions and __gfs2_log_flush(). |
| In the Linux kernel, the following vulnerability has been resolved:
bpf, sockmap: Take state lock for af_unix iter
When a BPF iterator program updates a sockmap, there is a race condition in
unix_stream_bpf_update_proto() where the `peer` pointer can become stale[1]
during a state transition TCP_ESTABLISHED -> TCP_CLOSE.
CPU0 bpf CPU1 close
-------- ----------
// unix_stream_bpf_update_proto()
sk_pair = unix_peer(sk)
if (unlikely(!sk_pair))
return -EINVAL;
// unix_release_sock()
skpair = unix_peer(sk);
unix_peer(sk) = NULL;
sock_put(skpair)
sock_hold(sk_pair) // UaF
More practically, this fix guarantees that the iterator program is
consistently provided with a unix socket that remains stable during
iterator execution.
[1]:
BUG: KASAN: slab-use-after-free in unix_stream_bpf_update_proto+0x155/0x490
Write of size 4 at addr ffff8881178c9a00 by task test_progs/2231
Call Trace:
dump_stack_lvl+0x5d/0x80
print_report+0x170/0x4f3
kasan_report+0xe4/0x1c0
kasan_check_range+0x125/0x200
unix_stream_bpf_update_proto+0x155/0x490
sock_map_link+0x71c/0xec0
sock_map_update_common+0xbc/0x600
sock_map_update_elem+0x19a/0x1f0
bpf_prog_bbbf56096cdd4f01_selective_dump_unix+0x20c/0x217
bpf_iter_run_prog+0x21e/0xae0
bpf_iter_unix_seq_show+0x1e0/0x2a0
bpf_seq_read+0x42c/0x10d0
vfs_read+0x171/0xb20
ksys_read+0xff/0x200
do_syscall_64+0xf7/0x5e0
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Allocated by task 2236:
kasan_save_stack+0x30/0x50
kasan_save_track+0x14/0x30
__kasan_slab_alloc+0x63/0x80
kmem_cache_alloc_noprof+0x1d5/0x680
sk_prot_alloc+0x59/0x210
sk_alloc+0x34/0x470
unix_create1+0x86/0x8a0
unix_stream_connect+0x318/0x15b0
__sys_connect+0xfd/0x130
__x64_sys_connect+0x72/0xd0
do_syscall_64+0xf7/0x5e0
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Freed by task 2236:
kasan_save_stack+0x30/0x50
kasan_save_track+0x14/0x30
kasan_save_free_info+0x3b/0x70
__kasan_slab_free+0x47/0x70
kmem_cache_free+0x11c/0x590
__sk_destruct+0x432/0x6e0
unix_release_sock+0x9b3/0xf60
unix_release+0x8a/0xf0
__sock_release+0xb0/0x270
sock_close+0x18/0x20
__fput+0x36e/0xac0
fput_close_sync+0xe5/0x1a0
__x64_sys_close+0x7d/0xd0
do_syscall_64+0xf7/0x5e0
entry_SYSCALL_64_after_hwframe+0x76/0x7e |
| In the Linux kernel, the following vulnerability has been resolved:
net/sched: taprio: fix use-after-free in advance_sched() on schedule switch
In advance_sched(), when should_change_schedules() returns true,
switch_schedules() is called to promote the admin schedule to oper.
switch_schedules() queues the old oper schedule for RCU freeing via
call_rcu(), but 'next' still points into an entry of the old oper
schedule. The subsequent 'next->end_time = end_time' and
rcu_assign_pointer(q->current_entry, next) are use-after-free.
Fix this by selecting 'next' from the new oper schedule immediately
after switch_schedules(), and using its pre-calculated end_time.
setup_first_end_time() sets the first entry's end_time to
base_time + interval when the schedule is installed, so the value
is already correct.
The deleted 'end_time = sched_base_time(admin)' assignment was also
harmful independently: it would overwrite the new first entry's
pre-calculated end_time with just base_time. |
| In the Linux kernel, the following vulnerability has been resolved:
tipc: fix double-free in tipc_buf_append()
tipc_msg_validate() can potentially reallocate the skb it is validating,
freeing the old one. In tipc_buf_append(), it was being called with a
pointer to a local variable which was a copy of the caller's skb
pointer.
If the skb was reallocated and validation subsequently failed, the error
handling path would free the original skb pointer, which had already
been freed, leading to double-free.
Fix this by checking if head now points to a newly allocated reassembled
skb. If it does, reassign *headbuf for later freeing operations. |
| In the Linux kernel, the following vulnerability has been resolved:
net: usb: rtl8150: fix use-after-free in rtl8150_start_xmit()
syzbot reported a KASAN slab-use-after-free read in rtl8150_start_xmit()
when accessing skb->len for tx statistics after usb_submit_urb() has
been called:
BUG: KASAN: slab-use-after-free in rtl8150_start_xmit+0x71f/0x760
drivers/net/usb/rtl8150.c:712
Read of size 4 at addr ffff88810eb7a930 by task kworker/0:4/5226
The URB completion handler write_bulk_callback() frees the skb via
dev_kfree_skb_irq(dev->tx_skb). The URB may complete on another CPU
in softirq context before usb_submit_urb() returns in the submitter,
so by the time the submitter reads skb->len the skb has already been
queued to the per-CPU completion_queue and freed by net_tx_action():
CPU A (xmit) CPU B (USB completion softirq)
------------ ------------------------------
dev->tx_skb = skb;
usb_submit_urb() --+
|-------> write_bulk_callback()
| dev_kfree_skb_irq(dev->tx_skb)
| net_tx_action()
| napi_skb_cache_put() <-- free
netdev->stats.tx_bytes |
+= skb->len; <-- UAF read
Fix it by caching skb->len before submitting the URB and using the
cached value when updating the tx_bytes counter.
The pre-existing tx_bytes semantics are preserved: the counter tracks
the original frame length (skb->len), not the ETH_ZLEN/USB-alignment
padded "count" value that is handed to the device. Changing that
would be a user-visible accounting change and is out of scope for
this UAF fix. |
| In the Linux kernel, the following vulnerability has been resolved:
net: ena: PHC: Fix potential use-after-free in get_timestamp
Move the phc->active check and resp pointer assignment to after
acquiring the spinlock. Previously, phc->active was checked without
holding the lock, and resp was cached from ena_dev->phc.virt_addr
before the lock was acquired.
If ena_com_phc_destroy() runs between the lockless active check and
the lock acquisition, it sets active=false, releases the lock, frees
the DMA memory, and sets virt_addr=NULL. The get_timestamp path would
then read a NULL virt_addr and dereference it.
With both the active check and the pointer read under the lock,
destroy cannot free the memory while get_timestamp is using it. |
| In the Linux kernel, the following vulnerability has been resolved:
drm/xe/dma-buf: handle empty bo and UAF races
There look to be some nasty races here when triggering the
invalidate_mappings hook:
1) We do xe_bo_alloc() followed by the attach, before the actual full bo
init step in xe_dma_buf_init_obj(). However the bo is visible on the
attachments list after the attach. This is bad since exporter driver,
say amdgpu, can at any time call back into our invalidate_mappings hook,
with an empty/bogus bo, leading to potential bugs/crashes.
2) Similar to 1) but here we get a UAF, when the invalidate_mappings
hook is triggered. For example, we get as far as xe_bo_init_locked()
but this fails in some way. But here the bo will be freed on error, but
we still have it attached from dma-buf pov, so if the
invalidate_mappings is now triggered then the bo we access is gone and
we trigger UAF and more bugs/crashes.
To fix this, move the attach step until after we actually have a fully
set up buffer object. Note that the bo is not published to userspace
until later, so not sure what the comment "Don't publish the bo
until we have a valid attachment", is referring to.
We have at least two different customers reporting hitting a NULL ptr
deref in evict_flags when importing something from amdgpu, followed by
triggering the evict flow. Hit rate is also pretty low, which would
hint at some kind of race, so something like 1) or 2) might explain
this.
v2:
- Shuffle the order of the ops slightly (no functional change)
- Improve the comment to better explain the ordering (Matt B)
(cherry picked from commit af1f2ad0c59fe4e2f924c526f66e968289d77971) |
| In the Linux kernel, the following vulnerability has been resolved:
net: qrtr: fix refcount saturation and potential UAF in qrtr_port_remove
In qrtr_port_remove(), the socket reference count is decremented via
__sock_put() before the port is removed from the qrtr_ports XArray and
before the RCU grace period elapses.
This breaks the fundamental RCU update paradigm. It exposes a race
window where a concurrent RCU reader (such as qrtr_reset_ports() or
qrtr_port_lookup()) can obtain a pointer to the socket from the XArray,
and attempt to call sock_hold() on a socket whose reference count has
already dropped to zero.
This exact race condition was hit during syzkaller fuzzing, leading to
the following refcount saturation warning and a potential Use-After-Free:
refcount_t: saturated; leaking memory.
WARNING: CPU: 3 PID: 1273 at lib/refcount.c:22 refcount_warn_saturate+0xae/0x1d0
Modules linked in: qrtr(+) bochs drm_shmem_helper ...
Call Trace:
<TASK>
qrtr_reset_ports net/qrtr/af_qrtr.c:768 [inline] [qrtr]
__qrtr_bind.isra.0+0x48b/0x570 net/qrtr/af_qrtr.c:805 [qrtr]
qrtr_bind+0x17d/0x210 net/qrtr/af_qrtr.c:901 [qrtr]
kernel_bind+0xe4/0x120 net/socket.c:3592
qrtr_ns_init+0x1a6/0x380 net/qrtr/ns.c:715 [qrtr]
qrtr_proto_init+0x3b/0xff0 net/qrtr/af_qrtr.c:169 [qrtr]
do_one_initcall+0xf5/0x5e0 init/main.c:1283
...
</TASK>
Fix this by deferring the reference count decrement until after the
xa_erase() and the synchronize_rcu() complete.
(Note: The v1 of this patch incorrectly replaced __sock_put() with
sock_put(). As Simon Horman pointed out, the callers of qrtr_port_remove()
still hold a reference to the socket, so freeing the socket memory here
would lead to a subsequent UAF in the caller. Thus, the __sock_put() is
kept, but only repositioned to close the RCU race.) |
| In the Linux kernel, the following vulnerability has been resolved:
sctp: purge outqueue on stale COOKIE-ECHO handling
sctp_stream_update() is only invoked when the association is moved into
COOKIE_WAIT during association setup/reconfiguration. In this path, the
outbound stream scheduler state (stream->out_curr) is expected to be
clean, since no user data should have been transmitted yet unless the
state machine has already partially progressed.
However, a corner case exists in sctp_sf_do_5_2_6_stale(): when a
Stale Cookie ERROR is received, the association is rolled back from
COOKIE_ECHOED to COOKIE_WAIT. In this scenario, user data may already
have been queued and even bundled with the COOKIE-ECHO chunk.
During the rollback, sctp_stream_update() frees the old stream table
and installs a new one, but it does not invalidate stream->out_curr.
As a result, out_curr may still point to a freed sctp_stream_out
entry from the previous stream state.
Later, SCTP scheduler dequeue paths (FCFS, RR, PRIO, etc.) rely on
stream->out_curr->ext, which can lead to use-after-free once the old
stream state has been released via sctp_stream_free().
This results in crashes such as (reported by Yuqi):
BUG: KASAN: slab-use-after-free in sctp_sched_fcfs_dequeue+0x13a/0x140
Read of size 8 at addr ff1100004d4d3208 by task mini_poc/9312
CPU: 1 UID: 1001 PID: 9312 Comm: mini_poc Not tainted
7.1.0-rc1-00305-gbd3a4795d574 #5 PREEMPT(full)
sctp_sched_fcfs_dequeue+0x13a/0x140
sctp_outq_flush+0x1603/0x33e0
sctp_do_sm+0x31c9/0x5d30
sctp_assoc_bh_rcv+0x392/0x6f0
sctp_inq_push+0x1db/0x270
sctp_rcv+0x138d/0x3c10
Fix this by fully purging the association outqueue when handling the
Stale Cookie case. This ensures all pending transmit and retransmit
state is dropped, and any scheduler cached pointers are invalidated,
making it safe to rebuild stream state during COOKIE_WAIT restart.
Updating only stream->out_curr would be insufficient, since queued
and retransmittable data would still reference the old stream state and
trigger later use-after-free in dequeue paths. |
| In the Linux kernel, the following vulnerability has been resolved:
bpf: Free reuseport cBPF prog after RCU grace period.
Eulgyu Kim reported the splat below with a repro. [0]
The repro sets up a UDP reuseport group with a cBPF prog and
replaces it with a new one while another thread is sending
a UDP packet to the group.
The reuseport prog is freed by sk_reuseport_prog_free().
bpf_prog_put() is called for "e"BPF prog to destruct through
multiple stages while cBPF prog is freed immediately by
bpf_release_orig_filter() and bpf_prog_free().
If a reuseport prog is detached from the setsockopt() path
(reuseport_attach_prog() or reuseport_detach_prog()),
sk_reuseport_prog_free() is called without waiting for RCU
readers to complete, resulting in various bugs.
Let's defer freeing the reuseport cBPF prog after one RCU
grace period.
Note "e"BPF prog is safe as is unless the fast path starts
to touch fields destroyed in bpf_prog_put_deferred() and
__bpf_prog_put_noref().
[0]:
BUG: KASAN: vmalloc-out-of-bounds in reuseport_select_sock+0xedc/0x1220 net/core/sock_reuseport.c:596
Read of size 4 at addr ffffc9000051e004 by task slowme/10208
CPU: 6 UID: 1000 PID: 10208 Comm: slowme Not tainted 7.0.0-geb7ac95ff75e #32 PREEMPT(full)
Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
<IRQ>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xca/0x240 mm/kasan/report.c:482
kasan_report+0x118/0x150 mm/kasan/report.c:595
reuseport_select_sock+0xedc/0x1220 net/core/sock_reuseport.c:596
udp4_lib_lookup2+0x3bc/0x950 net/ipv4/udp.c:495
__udp4_lib_lookup+0x768/0xe20 net/ipv4/udp.c:723
__udp4_lib_lookup_skb+0x297/0x390 net/ipv4/udp.c:752
__udp4_lib_rcv+0x1312/0x2620 net/ipv4/udp.c:2752
ip_protocol_deliver_rcu+0x282/0x440 net/ipv4/ip_input.c:207
ip_local_deliver_finish+0x3bb/0x6f0 net/ipv4/ip_input.c:241
NF_HOOK+0x30c/0x3a0 include/linux/netfilter.h:318
NF_HOOK+0x30c/0x3a0 include/linux/netfilter.h:318
__netif_receive_skb_one_core net/core/dev.c:6181 [inline]
__netif_receive_skb net/core/dev.c:6294 [inline]
process_backlog+0xaa4/0x1960 net/core/dev.c:6645
__napi_poll+0xae/0x340 net/core/dev.c:7709
napi_poll net/core/dev.c:7772 [inline]
net_rx_action+0x5d7/0xf50 net/core/dev.c:7929
handle_softirqs+0x22b/0x870 kernel/softirq.c:622
do_softirq+0x76/0xd0 kernel/softirq.c:523
</IRQ>
<TASK>
__local_bh_enable_ip+0xf8/0x130 kernel/softirq.c:450
local_bh_enable include/linux/bottom_half.h:33 [inline]
rcu_read_unlock_bh include/linux/rcupdate.h:924 [inline]
__dev_queue_xmit+0x1dd7/0x3710 net/core/dev.c:4890
neigh_output include/net/neighbour.h:556 [inline]
ip_finish_output2+0xca9/0x1070 net/ipv4/ip_output.c:237
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip_output+0x29f/0x450 net/ipv4/ip_output.c:438
ip_send_skb+0x45/0xc0 net/ipv4/ip_output.c:1508
udp_send_skb+0xb04/0x1510 net/ipv4/udp.c:1195
udp_sendmsg+0x1a71/0x2350 net/ipv4/udp.c:1485
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg net/socket.c:742 [inline]
__sys_sendto+0x554/0x680 net/socket.c:2206
__do_sys_sendto net/socket.c:2213 [inline]
__se_sys_sendto net/socket.c:2209 [inline]
__x64_sys_sendto+0xde/0x100 net/socket.c:2209
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x160/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x415a2d
Code: b3 66 2e 0f 1f 84 00 00 00 00 00 66 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f6bc31e41e8 EFLAGS: 00000212 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f6bc31e4cdc RCX: 0000000000415a2d
RDX: 0000000000000001 RSI: 00007f6bc31e421f RDI: 0000000000000003
RBP: 00007f6bc31e4240 R08: 00007f6bc31e4220 R09: 0000000000000010
R10: 0000000000000000 R11:
---truncated--- |
| In the Linux kernel, the following vulnerability has been resolved:
net/sched: act_ct: Only release RCU read lock after ct_ft
When looking up a flow table in act_ct in tcf_ct_flow_table_get(),
rhashtable_lookup_fast() internally opens and closes an RCU read critical
section before returning ct_ft.
The tcf_ct_flow_table_cleanup_work() can complete before refcount_inc_not_zero()
is invoked on the returned ct_ft resulting in a UAF on the already freed ct_ft
object. This vulnerability can lead to privilege escalation.
Analysis from zdi-disclosures@trendmicro.com:
When initializing act_ct, tcf_ct_init() is called, which internally triggers
tcf_ct_flow_table_get().
static int tcf_ct_flow_table_get(struct net *net, struct tcf_ct_params *params)
{
struct zones_ht_key key = { .net = net, .zone = params->zone };
struct tcf_ct_flow_table *ct_ft;
int err = -ENOMEM;
mutex_lock(&zones_mutex);
ct_ft = rhashtable_lookup_fast(&zones_ht, &key, zones_params); // [1]
if (ct_ft && refcount_inc_not_zero(&ct_ft->ref)) // [2]
goto out_unlock;
...
}
static __always_inline void *rhashtable_lookup_fast(
struct rhashtable *ht, const void *key,
const struct rhashtable_params params)
{
void *obj;
rcu_read_lock();
obj = rhashtable_lookup(ht, key, params);
rcu_read_unlock();
return obj;
}
At [1], rhashtable_lookup_fast() looks up and returns the corresponding ct_ft
from zones_ht . The lookup is performed within an RCU read critical section
through rcu_read_lock() / rcu_read_unlock(), which prevents the object from
being freed. However, at the point of function return, rcu_read_unlock() has
already been called, and there is nothing preventing ct_ft from being freed
before reaching refcount_inc_not_zero(&ct_ft->ref) at [2]. This interval becomes
the race window, during which ct_ft can be freed.
Free Process:
tcf_ct_flow_table_put() is executed through the path tcf_ct_cleanup() call_rcu()
tcf_ct_params_free_rcu() tcf_ct_params_free() tcf_ct_flow_table_put().
static void tcf_ct_flow_table_put(struct tcf_ct_flow_table *ct_ft)
{
if (refcount_dec_and_test(&ct_ft->ref)) {
rhashtable_remove_fast(&zones_ht, &ct_ft->node, zones_params);
INIT_RCU_WORK(&ct_ft->rwork, tcf_ct_flow_table_cleanup_work); // [3]
queue_rcu_work(act_ct_wq, &ct_ft->rwork);
}
}
At [3], tcf_ct_flow_table_cleanup_work() is scheduled as RCU work
static void tcf_ct_flow_table_cleanup_work(struct work_struct *work)
{
struct tcf_ct_flow_table *ct_ft;
struct flow_block *block;
ct_ft = container_of(to_rcu_work(work), struct tcf_ct_flow_table,
rwork);
nf_flow_table_free(&ct_ft->nf_ft);
block = &ct_ft->nf_ft.flow_block;
down_write(&ct_ft->nf_ft.flow_block_lock);
WARN_ON(!list_empty(&block->cb_list));
up_write(&ct_ft->nf_ft.flow_block_lock);
kfree(ct_ft); // [4]
module_put(THIS_MODULE);
}
tcf_ct_flow_table_cleanup_work() frees ct_ft at [4]. When this function executes
between [1] and [2], UAF occurs.
This race condition has a very short race window, making it generally
difficult to trigger. Therefore, to trigger the vulnerability an msleep(100) was
inserted after[1] |
| In the Linux kernel, the following vulnerability has been resolved:
KVM: arm64: Reassign nested_mmus array behind mmu_lock
kvm->arch.nested_mmus[] is walked under kvm->mmu_lock, including from the
MMU notifier path (kvm_unmap_gfn_range() -> kvm_nested_s2_unmap()), which
can run at any time. kvm_vcpu_init_nested() reallocates the array and frees
the old buffer while holding only kvm->arch.config_lock, so such a walker
can reference the freed array.
Allocate the new array outside of mmu_lock, as the allocation can sleep.
Under the lock, copy the existing entries, fix up the back pointers and
reassign the array. Free the old buffer after dropping the lock, as
kvfree() can sleep as well. |
| In the Linux kernel, the following vulnerability has been resolved:
lib: test_hmm: evict device pages on file close to avoid use-after-free
Patch series "Minor hmm_test fixes and cleanups".
Two bugfixes a cleanup for the HMM kernel selftests. These were mostly
reported by Zenghui Yu with special thanks to Lorenzo for analysing and
pointing out the problems.
This patch (of 3):
When dmirror_fops_release() is called it frees the dmirror struct but
doesn't migrate device private pages back to system memory first. This
leaves those pages with a dangling zone_device_data pointer to the freed
dmirror.
If a subsequent fault occurs on those pages (eg. during coredump) the
dmirror_devmem_fault() callback dereferences the stale pointer causing a
kernel panic. This was reported [1] when running mm/ksft_hmm.sh on arm64,
where a test failure triggered SIGABRT and the resulting coredump walked
the VMAs faulting in the stale device private pages.
Fix this by calling dmirror_device_evict_chunk() for each devmem chunk in
dmirror_fops_release() to migrate all device private pages back to system
memory before freeing the dmirror struct. The function is moved earlier
in the file to avoid a forward declaration. |
| In the Linux kernel, the following vulnerability has been resolved:
procfs: fix missing RCU protection when reading real_parent in do_task_stat()
When reading /proc/[pid]/stat, do_task_stat() accesses task->real_parent
without proper RCU protection, which leads to:
cpu 0 cpu 1
----- -----
do_task_stat
var = task->real_parent
release_task
call_rcu(delayed_put_task_struct)
task_tgid_nr_ns(var)
rcu_read_lock <--- Too late to protect task->real_parent!
task_pid_ptr <--- UAF!
rcu_read_unlock
This patch uses task_ppid_nr_ns() instead of task_tgid_nr_ns() to add
proper RCU protection for accessing task->real_parent. |
| In the Linux kernel, the following vulnerability has been resolved:
sctp: revalidate list cursor after sctp_sendmsg_to_asoc() in SCTP_SENDALL
The SCTP_SENDALL path in sctp_sendmsg() iterates ep->asocs with
list_for_each_entry_safe(), which caches the next entry in @tmp before
the loop body runs. The body calls sctp_sendmsg_to_asoc(), which may
drop the socket lock inside sctp_wait_for_sndbuf().
While the lock is dropped, another thread can SCTP_SOCKOPT_PEELOFF the
association cached in @tmp, migrating it to a new endpoint via
sctp_sock_migrate() (list_del_init() + list_add_tail() to
newep->asocs), and optionally close the new socket which frees the
association via kfree_rcu(). The cached @tmp can also be freed by a
network ABORT for that association, processed in softirq while the
lock is dropped.
sctp_wait_for_sndbuf() revalidates @asoc (the current entry) on re-lock
via the "sk != asoc->base.sk" and "asoc->base.dead" checks, but nothing
revalidates @tmp. After a successful return, the iterator advances to
the stale @tmp, yielding either a use-after-free (if the peeled socket
was closed) or a list-walk onto the new endpoint's list head (type
confusion of &newep->asocs as a struct sctp_association *).
Both are reachable from CapEff=0; the type-confusion path gives
controlled indirect call via the outqueue.sched->init_sid pointer.
Fix by re-deriving @tmp from @asoc after sctp_sendmsg_to_asoc()
returns. @asoc is known to still be on ep->asocs at that point: the
only callers that list_del an association from ep->asocs are
sctp_association_free() (which sets asoc->base.dead) and
sctp_assoc_migrate() (which changes asoc->base.sk), and
sctp_wait_for_sndbuf() checks both under the lock before any
successful return; a tripped check propagates as err < 0 and the loop
bails before the re-derive.
The SCTP_ABORT path in sctp_sendmsg_check_sflags() returns 0 and the
loop hits 'continue' before sctp_sendmsg_to_asoc() is ever called, so
the @tmp cached by list_for_each_entry_safe() still covers the
lock-held free that ba59fb027307 ("sctp: walk the list of asoc
safely") was added for. |
| In the Linux kernel, the following vulnerability has been resolved:
exit: prevent preemption of oopsing TASK_DEAD task
When an already-exiting task oopses, make_task_dead() currently calls
do_task_dead() with preemption enabled. That is forbidden:
do_task_dead() calls __schedule(), which has a comment saying "WARNING:
must be called with preemption disabled!".
If an oopsing task is preempted in do_task_dead(), between becoming
TASK_DEAD and entering the scheduler explicitly, bad things happen:
finish_task_switch() assumes that once the scheduler has switched away
from a TASK_DEAD task, the task can never run again and its stack is no
longer needed; but that assumption apparently doesn't hold if the dead
task was preempted (the SM_PREEMPT case).
This means that the scheduler ends up repeatedly dropping references on
the dead task's stack, which can lead to use-after-free or double-free
of the entire task stack; in other words, two tasks can end up running
on the same stack, resulting in various kinds of memory corruption.
(This does not just affect "recursively oopsing" tasks; it is enough to
oops once during task exit, for example in a file_operations::release
handler) |
| In the Linux kernel, the following vulnerability has been resolved:
net: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels
seg6_input_core() and rpl_input() call ip6_route_input() which sets a
NOREF dst on the skb, then pass it to dst_cache_set_ip6() invoking
dst_hold() unconditionally.
On PREEMPT_RT, ksoftirqd is preemptible and a higher-priority task can
release the underlying pcpu_rt between the lookup and the caching
through a concurrent FIB lookup on a shared nexthop.
Simplified race sequence:
ksoftirqd/X higher-prio task (same CPU X)
----------- --------------------------------
seg6_input_core(,skb)/rpl_input(skb)
dst_cache_get()
-> miss
ip6_route_input(skb)
-> ip6_pol_route(,skb,flags)
[RT6_LOOKUP_F_DST_NOREF in flags]
-> FIB lookup resolves fib6_nh
[nhid=N route]
-> rt6_make_pcpu_route()
[creates pcpu_rt, refcount=1]
pcpu_rt->sernum = fib6_sernum
[fib6_sernum=W]
-> cmpxchg(fib6_nh.rt6i_pcpu,
NULL, pcpu_rt)
[slot was empty, store succeeds]
-> skb_dst_set_noref(skb, dst)
[dst is pcpu_rt, refcount still 1]
rt_genid_bump_ipv6()
-> bumps fib6_sernum
[fib6_sernum from W to Z]
ip6_route_output()
-> ip6_pol_route()
-> FIB lookup resolves fib6_nh
[nhid=N]
-> rt6_get_pcpu_route()
pcpu_rt->sernum != fib6_sernum
[W <> Z, stale]
-> prev = xchg(rt6i_pcpu, NULL)
-> dst_release(prev)
[prev is pcpu_rt,
refcount 1->0, dead]
dst = skb_dst(skb)
[dst is the dead pcpu_rt]
dst_cache_set_ip6(dst)
-> dst_hold() on dead dst
-> WARN / use-after-free
For the race to occur, ksoftirqd must be preemptible (PREEMPT_RT without
PREEMPT_RT_NEEDS_BH_LOCK) and a concurrent task must be able to release
the pcpu_rt. Shared nexthop objects provide such a path, as two routes
pointing to the same nhid share the same fib6_nh and its rt6i_pcpu
entry.
Fix seg6_input_core() and rpl_input() by calling skb_dst_force() after
ip6_route_input() to force the NOREF dst into a refcounted one before
caching.
The output path is not affected as ip6_route_output() already returns a
refcounted dst. |
| In the Linux kernel, the following vulnerability has been resolved:
fbdev: defio: Disconnect deferred I/O from the lifetime of struct fb_info
Hold state of deferred I/O in struct fb_deferred_io_state. Allocate an
instance as part of initializing deferred I/O and remove it only after
the final mapping has been closed. If the fb_info and the contained
deferred I/O meanwhile goes away, clear struct fb_deferred_io_state.info
to invalidate the mapping. Any access will then result in a SIGBUS
signal.
Fixes a long-standing problem, where a device hot-unplug happens while
user space still has an active mapping of the graphics memory. The hot-
unplug frees the instance of struct fb_info. Accessing the memory will
operate on undefined state. |
| In the Linux kernel, the following vulnerability has been resolved:
net/rds: reset op_nents when zerocopy page pin fails
When iov_iter_get_pages2() fails in rds_message_zcopy_from_user(),
the pinned pages are released with put_page(), and
rm->data.op_mmp_znotifier is cleared. But we fail to properly
clear rm->data.op_nents.
Later when rds_message_purge() is called from rds_sendmsg() the
cleanup loop iterates over the incorrectly non zero number of
op_nents and frees them again.
Fix this by properly resetting op_nents when it should be in
rds_message_zcopy_from_user(). |
| In the Linux kernel, the following vulnerability has been resolved:
drm/amdgpu: Fix use-after-free race in VM acquire
Replace non-atomic vm->process_info assignment with cmpxchg()
to prevent race when parent/child processes sharing a drm_file
both try to acquire the same VM after fork().
(cherry picked from commit c7c573275ec20db05be769288a3e3bb2250ec618) |
