CVE-2024-35852 mlxsw: spectrum_acl_tcam: Fix memory leak when canceling rehash work
A memory leak in the Linux kernel mlxsw driver allows attackers to cause denial of service by exhausting system memory through repeated ACL region dismantling.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-35852?
CVE-2024-35852 is a medium-severity memory corruption vulnerability in Linux kernel, published on 17 May 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
mlxsw: spectrum_acl_tcam: Fix memory leak when canceling rehash work
The rehash delayed work is rescheduled with a delay if the number of credits at end of the work is not negative as supposedly it means that the migration ended. Otherwise, it is rescheduled immediately.
After "mlxsw: spectrum_acl_tcam: Fix possible use-after-free during rehash" the above is no longer accurate as a non-negative number of credits is no longer indicative of the migration being done. It can also happen if the work encountered an error in which case the migration will resume the next time the work is scheduled.
The significance of the above is that it is possible for the work to be pending and associated with hints that were allocated when the migration started. This leads to the hints being leaked [1] when the work is canceled while pending as part of ACL region dismantle.
Fix by freeing the hints if hints are associated with a work that was canceled while pending.
Blame the original commit since the reliance on not having a pending work associated with hints is fragile.
[1] unreferenced object 0xffff88810e7c3000 (size 256): comm "kworker/0:16", pid 176, jiffies 4295460353 hex dump (first 32 bytes): 00 30 95 11 81 88 ff ff 61 00 00 00 00 00 00 80 .0......a....... 00 00 61 00 40 00 00 00 00 00 00 00 04 00 00 00 ..a.@........... backtrace (crc 2544ddb9): [<00000000cf8cfab3>] kmalloc_trace+0x23f/0x2a0 [<000000004d9a1ad9>] objagg_hints_get+0x42/0x390 [<000000000b143cf3>] mlxsw_sp_acl_erp_rehash_hints_get+0xca/0x400 [<0000000059bdb60a>] mlxsw_sp_acl_tcam_vregion_rehash_work+0x868/0x1160 [<00000000e81fd734>] process_one_work+0x59c/0xf20 [<00000000ceee9e81>] worker_thread+0x799/0x12c0 [<00000000bda6fe39>] kthread+0x246/0x300 [<0000000070056d23>] ret_from_fork+0x34/0x70 [<00000000dea2b93e>] ret_from_fork_asm+0x1a/0x30
Weakness: CWE-401
Which versions are affected by CVE-2024-35852?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-35852?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2024-35852 being exploited?
There is no known exploitation of CVE-2024-35852 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-42139, BELL-CVE-2024-35852, DEBIAN-CVE-2024-35852, GHSA-r32h-q4vw-rvf3, UBUNTU-CVE-2024-35852.