Description
In the Linux kernel, the following vulnerability has been resolved: bpf: Keep refcount_acquire nullable for borrowed RCU kptrs bpf_refcount_acquire() is fallible for a borrowed reference because the object may have reached a zero refcount. The verifier therefore keeps KF_RET_NULL on the return value unless the argument is an owning reference. An RCU-protected load of a local kptr is marked MEM_ALLOC, but it only receives NON_OWN_REF when the pointee contains a graph node. A refcounted object without a graph node consequently looks like an owning reference even though the loaded register has no acquired reference state. If the program drops the last real reference while remaining in the RCU critical section, refcount_inc_not_zero() returns NULL while the verifier treats the result as non-NULL. Only classify the argument as owning when it is backed by a verifier-tracked reference. This retains the non-NULL return for pointers from bpf_obj_new(), bpf_kptr_xchg(), or an earlier successful acquisition, while requiring a NULL check for borrowed RCU kptrs. [ kkd: Rewrote commit log ]
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
1b12171533a9bb23cf6fba7262b479028b65e1e8 to < 85bfc8b6db43502444c428eaa2de20bdd2fb9064affected1b12171533a9bb23cf6fba7262b479028b65e1e8 to < 8d19e2cdfba9ba8c8eb6a459cd666bec00a1d2c6affected1b12171533a9bb23cf6fba7262b479028b65e1e8 to < 85074498228a2500ea8b8039c49cc1ab8ad5328faffected1b12171533a9bb23cf6fba7262b479028b65e1e8 to < dc36739e5cc9f60485418a910b42bc95339218d2affected
Linux Linux
Default version status: affected
6.8affected0 to < 6.8unaffected6.12.114 to ≤ 6.12.*unaffected6.18.57 to ≤ 6.18.*unaffected7.2.7 to ≤ 7.2.*unaffected7.3 to ≤ *unaffected