CVE-2026-46106
Description
In the Linux kernel, the following vulnerability has been resolved: eventfs: Hold eventfs_mutex and SRCU when remount walks events Commit 340f0c7067a9 ("eventfs: Update all the eventfs_inodes from the events descriptor") had eventfs_set_attrs() recurse through ei->children on remount. The walk only holds the rcu_read_lock() taken by tracefs_apply_options() over tracefs_inodes, which is wrong: - list_for_each_entry over ei->children races with the list_del_rcu() in eventfs_remove_rec() -- LIST_POISON1 deref, same shape as d2603279c7d6. - eventfs_inodes are freed via call_srcu(&eventfs_srcu, ...). rcu_read_lock() does not extend an SRCU grace period, so ti->private can be reclaimed under the walk. - The writes to ei->attr race with eventfs_set_attr(), which holds eventfs_mutex. Reproducer: while :; do mount -o remount,uid=$((RANDOM%1000)) /sys/kernel/tracing; done & while :; do echo "p:kp submit_bio" > /sys/kernel/tracing/kprobe_events echo > /sys/kernel/tracing/kprobe_events done Wrap the events portion of tracefs_apply_options() in eventfs_remount_lock()/_unlock() that take eventfs_mutex and srcu_read_lock(&eventfs_srcu). eventfs_set_attrs() doesn't sleep so the nested rcu_read_lock() is fine; lockdep_assert_held() pins the contract. Comment in tracefs_drop_inode() said "RCU cycle" -- it is SRCU.
How to fix
- linux linux_kernel6.6.140, 6.12.88, 6.18.30, 7.0.7 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| linux linux_kernel | 6.6.35 ≤ v < 6.6.140, 6.9.6 ≤ v < 6.12.88, 6.13 ≤ v < 6.18.30, 6.19 ≤ v < 7.0.7 | 6.6.140, 6.12.88, 6.18.30, 7.0.7 |
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