FKIE_CVE-2026-31507
Vulnerability from fkie_nvd - Published: 2026-04-22 14:16 - Updated: 2026-04-28 15:05
Severity ?
Summary
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:
<TASK>
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
</TASK>
BUG: kernel NULL pointer dereference, address: 0000000000000020
RIP: 0010:smc_rx_update_consumer+0x8d/0x350
Call Trace:
<TASK>
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
</TASK>
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.
References
Impacted products
| Vendor | Product | Version | |
|---|---|---|---|
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | 4.18 | |
| linux | linux_kernel | 7.0 | |
| linux | linux_kernel | 7.0 | |
| linux | linux_kernel | 7.0 | |
| linux | linux_kernel | 7.0 | |
| linux | linux_kernel | 7.0 | |
| linux | linux_kernel | 7.0 | |
| linux | linux_kernel | 7.0 |
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"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/smc: fix double-free of smc_spd_priv when tee() duplicates splice pipe buffer\n\nsmc_rx_splice() allocates one smc_spd_priv per pipe_buffer and stores\nthe pointer in pipe_buffer.private. The pipe_buf_operations for these\nbuffers used .get = generic_pipe_buf_get, which only increments the page\nreference count when tee(2) duplicates a pipe buffer. The smc_spd_priv\npointer itself was not handled, so after tee() both the original and the\ncloned pipe_buffer share the same smc_spd_priv *.\n\nWhen both pipes are subsequently released, smc_rx_pipe_buf_release() is\ncalled twice against the same object:\n\n 1st call: kfree(priv) sock_put(sk) smc_rx_update_cons() [correct]\n 2nd call: kfree(priv) sock_put(sk) smc_rx_update_cons() [UAF]\n\nKASAN reports a slab-use-after-free in smc_rx_pipe_buf_release(), which\nthen escalates to a NULL-pointer dereference and kernel panic via\nsmc_rx_update_consumer() when it chases the freed priv-\u003esmc pointer:\n\n BUG: KASAN: slab-use-after-free in smc_rx_pipe_buf_release+0x78/0x2a0\n Read of size 8 at addr ffff888004a45740 by task smc_splice_tee_/74\n Call Trace:\n \u003cTASK\u003e\n dump_stack_lvl+0x53/0x70\n print_report+0xce/0x650\n kasan_report+0xc6/0x100\n smc_rx_pipe_buf_release+0x78/0x2a0\n free_pipe_info+0xd4/0x130\n pipe_release+0x142/0x160\n __fput+0x1c6/0x490\n __x64_sys_close+0x4f/0x90\n do_syscall_64+0xa6/0x1a0\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n \u003c/TASK\u003e\n\n BUG: kernel NULL pointer dereference, address: 0000000000000020\n RIP: 0010:smc_rx_update_consumer+0x8d/0x350\n Call Trace:\n \u003cTASK\u003e\n smc_rx_pipe_buf_release+0x121/0x2a0\n free_pipe_info+0xd4/0x130\n pipe_release+0x142/0x160\n __fput+0x1c6/0x490\n __x64_sys_close+0x4f/0x90\n do_syscall_64+0xa6/0x1a0\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n \u003c/TASK\u003e\n Kernel panic - not syncing: Fatal exception\n\nBeyond the memory-safety problem, duplicating an SMC splice buffer is\nsemantically questionable: smc_rx_update_cons() would advance the\nconsumer cursor twice for the same data, corrupting receive-window\naccounting. A refcount on smc_spd_priv could fix the double-free, but\nthe cursor-accounting issue would still need to be addressed separately.\n\nThe .get callback is invoked by both tee(2) and splice_pipe_to_pipe()\nfor partial transfers; both will now return -EFAULT. Users who need\nto duplicate SMC socket data must use a copy-based read path."
}
],
"id": "CVE-2026-31507",
"lastModified": "2026-04-28T15:05:10.837",
"metrics": {
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"attackComplexity": "LOW",
"attackVector": "LOCAL",
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"baseScore": 7.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"published": "2026-04-22T14:16:49.523",
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Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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