** Changed in: linux (Ubuntu Noble)
Importance: Critical => High
** Changed in: linux (Ubuntu Plucky)
Importance: Critical => High
** Changed in: linux (Ubuntu Questing)
Importance: Critical => High
** Changed in: linux (Ubuntu Questing)
Status: In Progress => Fix Committed
** Changed in: linux (Ubuntu Noble)
Status: In Progress => Fix Committed
** Changed in: linux (Ubuntu Plucky)
Status: In Progress => Fix Committed
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https://bugs.launchpad.net/bugs/2122554
Title:
memory leaks when configuring a small rate limit in audit
Status in linux package in Ubuntu:
Fix Committed
Status in linux source package in Noble:
Fix Committed
Status in linux source package in Plucky:
Fix Committed
Status in linux source package in Questing:
Fix Committed
Bug description:
[Impact]
When the audit rate limit is exceeded, memory starts leaking, this can be
observed by:
watch -d -n 1 grep -i SUnreclaim' /proc/meminfo
Unreclaimable slab grows rapidly and lead to run out of all available memory
Only reboot can recover it.
5.15 kernel doesn't have this issue, it's introduced later than 5.19 kernel,
and caused by LSM stacking code.
[Fix]
This upstream patch fixes the issue:
https://lore.kernel.org/audit/[email protected]/T/#t
and merged into maintainer's tree:
https://github.com/linux-audit/audit-kernel/commit/d2c773159327f4d2f6438acf1ae2ae9ac0ca46a9
[Test Plan]
Add the following line to set a small rate limit in
/etc/audit/rules.d/audit.rules:
-a always,exit -F arch=b64 -S openat -S truncate -S ftruncate -F exit=-EACCES
-F auid>=1000 -F auid!=4294967295 -k access -r 100
Trigger permission denied by running the following command as a normal user:
while :; do cat /proc/1/environ; done
Make sure we see the warning message in kernel log:
[ 2531.862184] audit: rate limit exceeded
[Where problems could occur]
Originally the skb is leak and no one is able to process or free it anymore.
The above patch just frees the leaking skb when rate limit is exceeded,
there won't be any additional impact.
[ Other Info ]
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2098730
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