Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: bpf: fix UAF by restoring RCU-delayed inode freeing in bpffs commit 4f375ade6aa9 ("bpf: Avoid RCU context warning when unpinning htab with internal structs") moved inode cleanup from ->free_inode() into ->destroy_inode() to avoid sleeping in RCU context when calling bpf_any_put(). However this removed the RCU delay on freeing the inode itself and the cached symlink body (i_link), both of which can be accessed by RCU pathwalk (pick_link, may_lookup etc.). This causes a use-after-free when a concurrent unlinkat() drops the last inode reference and destroy_inode() frees the inode immediately, while another task is still walking the path in RCU mode and reads inode->i_opflags (offset +2) inside current_time() -> is_mgtime(). KASAN reports: BUG: KASAN: slab-use-after-free in is_mgtime include/linux/fs.h:2313 Read of size 2 at addr ffff8880407e4282 (offset +2 = i_opflags) The rules (per Al Viro): ->destroy_inode() called immediately, can sleep, use for blocking cleanup e.g. bpf_any_put() ->free_inode() called after RCU grace period, use for freeing inode and anything RCU-accessible e.g. i_link Fix: split the two concerns properly: - keep bpf_any_put() in bpf_destroy_inode() since it is blocking and needs to run promptly - introduce bpf_free_inode() to handle kfree(i_link) and free_inode_nonrcu() with proper RCU delay, preventing the UAF
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected e28616ca3d67e745ecb2f10eba4a626e1fc9a203 before ea1c243c39e32b7fc1c2edfe32081ff7e30a877c; affected 743a620c661994c7f0938e6dd32fb0883fb1e0ea before 5fecb71c10c28aef276ba49c718dc961745fdcf0; affected b6e9645be9eb93f7aff3ca887f8edb6f1d63358f before c70d0f9114c3cc156f6029a400c4eb7e6f7c82b2; affected ee04cff9ed4d6bb25802f5cecfcd0750500410f3 before 53649846e0437d1d9b7cb993cfe54c367addf7ae; affected 4f375ade6aa9f37fd72d7a78682f639772089eed before 61f19729728243c82476dee31315143ed3275e7f; affected 4f375ade6aa9f37fd72d7a78682f639772089eed before 0497ff765746d9b2d17445c8f7cc737b36c0152a; affected 4f375ade6aa9f37fd72d7a78682f639772089eed before b93c55b4932dd7e32dca8cf34a3443cc87a02906; affected de2d2baecc84cc7fca52eec2b9b55d89c93e3565; affected 5.15.195 before 5.15.212; affected 6.1.157 before 6.1.178; affected 6.6.113 before 6.6.145; affected 6.12.54 before 6.12.97; affected 6.17.4 before 6.18 |
| Linux / Linux | affected 6.18; unaffected 0 before 6.18; unaffected 5.15.212 through 5.15.*; unaffected 6.1.178 through 6.1.*; unaffected 6.6.145 through 6.6.*; unaffected 6.12.97 through 6.12.*; unaffected 6.18.40 through 6.18.*; unaffected 7.1.5 through 7.1.*; unaffected 7.2 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/ea1c243c39e32b7fc1c2edfe32081ff7e30a877c
- https://git.kernel.org/stable/c/5fecb71c10c28aef276ba49c718dc961745fdcf0
- https://git.kernel.org/stable/c/c70d0f9114c3cc156f6029a400c4eb7e6f7c82b2
- https://git.kernel.org/stable/c/53649846e0437d1d9b7cb993cfe54c367addf7ae
- https://git.kernel.org/stable/c/61f19729728243c82476dee31315143ed3275e7f
- https://git.kernel.org/stable/c/0497ff765746d9b2d17445c8f7cc737b36c0152a
- https://git.kernel.org/stable/c/b93c55b4932dd7e32dca8cf34a3443cc87a02906
ADP enrichment
No English description supplied.
No references supplied.