Description
In the Linux kernel, the following vulnerability has been resolved: eventfs: Free the eventfs_inode after an rcu grace period too tracefs_d_revalidate() reads ->is_freed of the eventfs_inode that dentry->d_fsdata points to, and ->d_revalidate() is called in rcu pathwalk mode with nothing but rcu_read_lock() held. The dentry itself stays around for such a walker, but tracefs_d_release() drops its reference to the eventfs_inode when the dentry is killed, and release_ei() then frees it after a grace period of eventfs_srcu. An SRCU grace period doesn't wait for rcu_read_lock() sections, so the walker can read an eventfs_inode that is already gone. With a pathwalk held up in tracefs_d_revalidate() while the dentry goes away: BUG: KASAN: slab-use-after-free in tracefs_d_revalidate+0x76/0x90 Read of size 1 at addr ff1100010152d8d0 by task walker/97 Call Trace: <TASK> tracefs_d_revalidate+0x76/0x90 lookup_fast+0x320/0x640 path_lookupat+0x160/0xb00 filename_lookup+0x1f1/0x5b0 vfs_statx+0xd7/0x3b0 vfs_fstatat+0x4d/0x90 __do_sys_newfstatat+0xa0/0x100 do_syscall_64+0x10e/0x5e0 entry_SYSCALL_64_after_hwframe+0x77/0x7f [...] Allocated by task 1: __kmalloc_cache_noprof+0x249/0x560 eventfs_create_dir+0x7a/0x590 event_create_dir+0x2fb/0xcf0 trace_add_event_call+0xbf/0x150 [...] Freed by task 11: kfree+0x1db/0x5b0 srcu_invoke_callbacks+0x3a3/0x620 process_one_work+0x937/0x1810 worker_thread+0x4f1/0xd60 Before commit 8e556432477e ("eventfs: Use SRCU for freeing eventfs_inodes") release_ei() used call_rcu(), which covered the walker, while eventfs_iterate() needs the SRCU grace period. Wait for both and chain call_rcu() from the SRCU callback.
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
8e556432477e97ad6179c61b61a32bf5f1af2355 to < 4586ef24ce390e8becb9f3e5852d5d3978b01c33affected8e556432477e97ad6179c61b61a32bf5f1af2355 to < 45fcfd5d9c10e0aa977ed5b9bd445707e01bb107affected8e556432477e97ad6179c61b61a32bf5f1af2355 to < 2cd88c498ecff8e22bf4c397b8eb226db70ac343affected2ef3d120d19faba3dec35b10a025b00db0284373affected384f383c5aa7bfd619d9f56a513a36e533428186affected6.6.46 to < 6.7affected6.10.5 to < 6.11affected
Linux Linux
Default version status: affected
6.11affected0 to < 6.11unaffected6.18.59 to ≤ 6.18.*unaffected7.2.13 to ≤ 7.2.*unaffected7.3 to ≤ *unaffected