CVE-2026-99032: net/smc: protect clcsock lifetime in smc_getname
In the Linux kernel, the following vulnerability has been resolved:
net/smc: protect clcsock lifetime in smcgetname
smcgetname() dereferences smc->clcsock without holding clcsockreleaselock. Link-group termination can release the CLC socket through smccloseactiveabort() while the SMC socket is still open, for example after shutdown(SHUTWR).
A getsockname() caller can load smc->clcsock, then the termination worker can clear the pointer and call sockrelease() before the caller accesses clcsock->ops or invokes getname(). This causes a use-after-free; if the worker clears the pointer before the load, it causes a NULL dereference. The syscall's file reference keeps the SMC socket alive but does not prevent asynchronous release of its CLC socket.
KASAN reported the following with test-only timing instrumentation:
BUG: KASAN: slab-use-after-free in smcgetname+0x19e/0x1b0 Read of size 8 at addr ffff888109abb4e0 by task poc/103 Call Trace: smcgetname+0x19e/0x1b0 dogetsockname+0xe5/0x170 sysgetsockname+0x8c/0x100
Allocated by task 95: sockallocinode+0x1e/0x280 sockalloc+0x3d/0x240 sockcreate+0x7e/0x430 smccreate+0x121/0x240
Freed by task 0: kmemcachefree+0xcc/0x340 rcucore+0x50a/0x1850
Last potentially related work creation: evict+0x446/0x6c0 smcclcsockrelease+0xa8/0xd0 smccloseactiveabort+0x26a/0x3a0 smclgrterminate.part.0+0x137/0x2e0
Hold clcsockreleaselock across the pointer check and the getname() callback to serialize with smcclcsockrelease(). Return -EBADF if the CLC socket has already been released, preserving the existing peer state check and the callback's return value otherwise.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Compensating control
In Linux kernel net/smc, hold clcsock_release_lock across the smc->clcsock pointer check and getname() call, serialize the callback with smc_clcsock_release(), and return -EBADF if the CLC socket pointer is absent.