net/smc: avoid NULL deref of conn->lnk in smc_msg_event tracepoint
The smc_msg_event tracepoint class, shared by smc_tx_sendmsg and
smc_rx_recvmsg, unconditionally dereferences smc->conn.lnk:
__string(name, smc->conn.lnk->ibname)
conn->lnk is only set for SMC-R; for SMC-D it is NULL. Other code on
these paths already handles this (e.g. !conn->lnk in
SMC_STAT_RMB_TX_SIZE_SMALL()). With the tracepoint enabled, the first
sendmsg()/recvmsg() on an SMC-D socket crashes:
Oops: general protection fault, probably for non-canonical address
KASAN: null-ptr-deref in range [...]
RIP: 0010:strlen+0x1e/0xa0
Call Trace:
trace_event_raw_event_smc_msg_event (net/smc/smc_tracepoint.h:44)
smc_rx_recvmsg (net/smc/smc_rx.c:515)
smc_recvmsg (net/smc/af_smc.c:2859)
__sys_recvfrom (net/socket.c:2315)
__x64_sys_recvfrom (net/socket.c:2326)
do_syscall_64
The faulting address 0x3e0 is offsetof(struct smc_link, ibname),
confirming the NULL ->lnk deref. Enabling the tracepoint requires
root, but the trigger itself is unprivileged: socket(AF_SMC, ...) has
no capability check, and SMC-D negotiation needs no admin step on
s390 or on x86 with the loopback ISM device loaded.
Log an empty device name for SMC-D instead of dereferencing NULL.
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Thu, 25 Jun 2026 00:15:00 +0000
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| Metrics |
threat_severity
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cvssV3_1
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Wed, 24 Jun 2026 13:15:00 +0000
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| Weaknesses | CWE-476 |
Wed, 24 Jun 2026 07:45:00 +0000
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| Description | In the Linux kernel, the following vulnerability has been resolved: net/smc: avoid NULL deref of conn->lnk in smc_msg_event tracepoint The smc_msg_event tracepoint class, shared by smc_tx_sendmsg and smc_rx_recvmsg, unconditionally dereferences smc->conn.lnk: __string(name, smc->conn.lnk->ibname) conn->lnk is only set for SMC-R; for SMC-D it is NULL. Other code on these paths already handles this (e.g. !conn->lnk in SMC_STAT_RMB_TX_SIZE_SMALL()). With the tracepoint enabled, the first sendmsg()/recvmsg() on an SMC-D socket crashes: Oops: general protection fault, probably for non-canonical address KASAN: null-ptr-deref in range [...] RIP: 0010:strlen+0x1e/0xa0 Call Trace: trace_event_raw_event_smc_msg_event (net/smc/smc_tracepoint.h:44) smc_rx_recvmsg (net/smc/smc_rx.c:515) smc_recvmsg (net/smc/af_smc.c:2859) __sys_recvfrom (net/socket.c:2315) __x64_sys_recvfrom (net/socket.c:2326) do_syscall_64 The faulting address 0x3e0 is offsetof(struct smc_link, ibname), confirming the NULL ->lnk deref. Enabling the tracepoint requires root, but the trigger itself is unprivileged: socket(AF_SMC, ...) has no capability check, and SMC-D negotiation needs no admin step on s390 or on x86 with the loopback ISM device loaded. Log an empty device name for SMC-D instead of dereferencing NULL. | |
| Title | net/smc: avoid NULL deref of conn->lnk in smc_msg_event tracepoint | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
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| References |
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Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-06-24T07:14:29.943Z
Reserved: 2026-06-09T07:44:35.370Z
Link: CVE-2026-52941
No data.
No data.
OpenCVE Enrichment
Updated: 2026-06-25T02:15:03Z