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CVE-2026-52941

net/smc: avoid NULL deref of conn->lnk in smc_msg_event tracepoint PUBLISHED

Description (CNA)

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.

Affected (CNA)

Vendor / productVersions
Linux / Linuxaffected aff3083f10bff7a37eaa2b4e6bc5fb627ddd5f84 before 68200112534bb2acd1d7117dc2d5c124868d866d; affected aff3083f10bff7a37eaa2b4e6bc5fb627ddd5f84 before 720c76b930c52cd58f50eb6b10569d03dccc7959; affected aff3083f10bff7a37eaa2b4e6bc5fb627ddd5f84 before b706d6d76a2a2793fe5ad0fbc2a75b6a460094ef; affected aff3083f10bff7a37eaa2b4e6bc5fb627ddd5f84 before d2ea0b8aef8746e147602eac87ca8538f4bc7e66; affected aff3083f10bff7a37eaa2b4e6bc5fb627ddd5f84 before 561cf66fa9b6c86dfe4e687d2d1aeaaa6739917f; affected aff3083f10bff7a37eaa2b4e6bc5fb627ddd5f84 before 7bf563badd37cb796df5477d2b78bb64148a1268
Linux / Linuxaffected 5.16; unaffected 0 before 5.16; unaffected 6.1.175 through 6.1.*; unaffected 6.6.142 through 6.6.*; unaffected 6.12.92 through 6.12.*; unaffected 6.18.34 through 6.18.*; unaffected 7.0.11 through 7.0.*; unaffected 7.1 through *

CWE

No CWE identifiers supplied.

References