Описание
In the Linux kernel, the following vulnerability has been resolved:
net/smc: fix double-free of smc_spd_priv when tee() duplicates splice pipe buffer
smc_rx_splice() allocates one smc_spd_priv per pipe_buffer and stores
the pointer in pipe_buffer.private. The pipe_buf_operations for these
buffers used .get = generic_pipe_buf_get, which only increments the page
reference count when tee(2) duplicates a pipe buffer. The smc_spd_priv
pointer itself was not handled, so after tee() both the original and the
cloned pipe_buffer share the same smc_spd_priv *.
When both pipes are subsequently released, smc_rx_pipe_buf_release() is
called twice against the same object:
1st call: kfree(priv) sock_put(sk) smc_rx_update_cons() [correct]
2nd call: kfree(priv) sock_put(sk) smc_rx_update_cons() [UAF]
KASAN reports a slab-use-after-free in smc_rx_pipe_buf_release(), which
then escalates to a NULL-pointer dereference and kernel panic via
smc_rx_update_consumer() when it chases the freed priv->smc pointer:
BUG: KASAN: slab-use-after-free in smc_rx_pipe_buf_release+0x78/0x2a0
Read of size 8 at addr ffff888004a45740 by task smc_splice_tee_/74
Call Trace:
dump_stack_lvl+0x53/0x70
print_report+0xce/0x650
kasan_report+0xc6/0x100
smc_rx_pipe_buf_release+0x78/0x2a0
free_pipe_info+0xd4/0x130
pipe_release+0x142/0x160
__fput+0x1c6/0x490
__x64_sys_close+0x4f/0x90
do_syscall_64+0xa6/0x1a0
entry_SYSCALL_64_after_hwframe+0x77/0x7f
BUG: kernel NULL pointer dereference, address: 0000000000000020
RIP: 0010:smc_rx_update_consumer+0x8d/0x350
Call Trace:
smc_rx_pipe_buf_release+0x121/0x2a0
free_pipe_info+0xd4/0x130
pipe_release+0x142/0x160
__fput+0x1c6/0x490
__x64_sys_close+0x4f/0x90
do_syscall_64+0xa6/0x1a0
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Kernel panic - not syncing: Fatal exception
Beyond the memory-safety problem, duplicating an SMC splice buffer is
semantically questionable: smc_rx_update_cons() would advance the
consumer cursor twice for the same data, corrupting receive-window
accounting. A refcount on smc_spd_priv could fix the double-free, but
the cursor-accounting issue would still need to be addressed separately.
The .get callback is invoked by both tee(2) and splice_pipe_to_pipe()
for partial transfers; both will now return -EFAULT. Users who need
to duplicate SMC socket data must use a copy-based read path.
A flaw was found in the Linux kernel's Stream Control Transmission Protocol (SMC) module. A local user can exploit this vulnerability by using the tee(2) system call to duplicate a splice pipe buffer, leading to a double-free condition. This double-free can result in a use-after-free error and a kernel null pointer dereference, ultimately causing a kernel panic and a denial of service on the affected system.
Отчет
Upstream rejects tee()/splice_pipe_to_pipe() paths that would duplicate SMC pipe buffers because refcounting alone cannot fix receive-window accounting. Red Hat advises patched kernels for SMC users. Unload smc where the protocol is unused.
Меры по смягчению последствий
To mitigate this issue, prevent the smc module from being loaded. See https://access.redhat.com/solutions/41278 for instructions.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 10 | kernel | Fix deferred | ||
| Red Hat Enterprise Linux 6 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel | Fix deferred | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Fix deferred | ||
| Red Hat Enterprise Linux 8 | kernel | Fix deferred | ||
| Red Hat Enterprise Linux 8 | kernel-rt | Fix deferred | ||
| Red Hat Enterprise Linux 9 | kernel | Fix deferred | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Fix deferred |
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Дополнительная информация
Статус:
EPSS
5.5 Medium
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: net/smc: fix double-free of smc_spd_priv when tee() duplicates splice pipe buffer smc_rx_splice() allocates one smc_spd_priv per pipe_buffer and stores the pointer in pipe_buffer.private. The pipe_buf_operations for these buffers used .get = generic_pipe_buf_get, which only increments the page reference count when tee(2) duplicates a pipe buffer. The smc_spd_priv pointer itself was not handled, so after tee() both the original and the cloned pipe_buffer share the same smc_spd_priv *. When both pipes are subsequently released, smc_rx_pipe_buf_release() is called twice against the same object: 1st call: kfree(priv) sock_put(sk) smc_rx_update_cons() [correct] 2nd call: kfree(priv) sock_put(sk) smc_rx_update_cons() [UAF] KASAN reports a slab-use-after-free in smc_rx_pipe_buf_release(), which then escalates to a NULL-pointer dereference and kernel panic via smc_rx_update_consumer() when it chases the freed priv->...
In the Linux kernel, the following vulnerability has been resolved: net/smc: fix double-free of smc_spd_priv when tee() duplicates splice pipe buffer smc_rx_splice() allocates one smc_spd_priv per pipe_buffer and stores the pointer in pipe_buffer.private. The pipe_buf_operations for these buffers used .get = generic_pipe_buf_get, which only increments the page reference count when tee(2) duplicates a pipe buffer. The smc_spd_priv pointer itself was not handled, so after tee() both the original and the cloned pipe_buffer share the same smc_spd_priv *. When both pipes are subsequently released, smc_rx_pipe_buf_release() is called twice against the same object: 1st call: kfree(priv) sock_put(sk) smc_rx_update_cons() [correct] 2nd call: kfree(priv) sock_put(sk) smc_rx_update_cons() [UAF] KASAN reports a slab-use-after-free in smc_rx_pipe_buf_release(), which then escalates to a NULL-pointer dereference and kernel panic via smc_rx_update_consumer() when it chases the freed
net/smc: fix double-free of smc_spd_priv when tee() duplicates splice pipe buffer
In the Linux kernel, the following vulnerability has been resolved: n ...
In the Linux kernel, the following vulnerability has been resolved: net/smc: fix double-free of smc_spd_priv when tee() duplicates splice pipe buffer smc_rx_splice() allocates one smc_spd_priv per pipe_buffer and stores the pointer in pipe_buffer.private. The pipe_buf_operations for these buffers used .get = generic_pipe_buf_get, which only increments the page reference count when tee(2) duplicates a pipe buffer. The smc_spd_priv pointer itself was not handled, so after tee() both the original and the cloned pipe_buffer share the same smc_spd_priv *. When both pipes are subsequently released, smc_rx_pipe_buf_release() is called twice against the same object: 1st call: kfree(priv) sock_put(sk) smc_rx_update_cons() [correct] 2nd call: kfree(priv) sock_put(sk) smc_rx_update_cons() [UAF] KASAN reports a slab-use-after-free in smc_rx_pipe_buf_release(), which then escalates to a NULL-pointer dereference and kernel panic via smc_rx_update_consumer() when it chases the fre...
EPSS
5.5 Medium
CVSS3