Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: net: serialize netif_running() check in enqueue_to_backlog() Syzbot reported a KASAN slab-use-after-free in fib_rules_lookup(). The root cause is a race condition where packets can escape the backlog flushing during device unregistration (e.g., during netns exit). Commit e9e4dd3267d0 ("net: do not process device backlog during unregistration") introduced a lockless netif_running() check in enqueue_to_backlog() to prevent queuing packets to an unregistering device. However, this creates a TOCTOU race window. A lockless transmitter (like veth_xmit) can pass the check before dev_close() clears IFF_UP. If the transmitter is then delayed, flush_all_backlogs() can run and finish before the transmitter grabs the backlog lock and queues the packet. The packet then escapes the flush and triggers UAF later when processed. Fix this by moving the netif_running() check inside the backlog lock. This serializes the check with the flush work (which also grabs the lock). We then either queue the packet before the flush runs (so it gets flushed), or check netif_running() after the flush/close completes (so it gets dropped).
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected e9e4dd3267d0c5234c5c0f47440456b10875dec9 before cbe10ea090ea9d6fa5ff50c9b44f2a86fe56f0b7; affected e9e4dd3267d0c5234c5c0f47440456b10875dec9 before b422e3eff0edf0975de4883929adbed28f9d08bc; affected e9e4dd3267d0c5234c5c0f47440456b10875dec9 before 2fface6e0bbd6314d1d9d071abf2c4d67548511c; affected e9e4dd3267d0c5234c5c0f47440456b10875dec9 before 46762cefe7f4e5bffc1eb467810a7bbb02e461d7; affected 78b6803a1961369d0b8350ff1f99b7375bbd7a8f; affected b5d73d9cdd6be22795499890ea928a6f57ef829c; affected f6533fed1bfa842e391ee50f9a9c5e963c71e579; affected 2095ab2456da766174cda8bc105d7a7b1bc70e16; affected f1fdb184aefa8447560e3ea0e605171592ffee41; affected f75c8a3015422128ca150e81c730bc2a471b5f4a; affected 3.2.71 before 3.3; affected 3.4.111 before 3.5; affected 3.12.48 before 3.13; affected 3.14.54 before 3.15; affected 3.18.22 before 3.19; affected 4.1.9 before 4.2 |
| Linux / Linux | affected 4.2; unaffected 0 before 4.2; unaffected 6.12.114 through 6.12.*; unaffected 6.18.57 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/cbe10ea090ea9d6fa5ff50c9b44f2a86fe56f0b7
- https://git.kernel.org/stable/c/b422e3eff0edf0975de4883929adbed28f9d08bc
- https://git.kernel.org/stable/c/2fface6e0bbd6314d1d9d071abf2c4d67548511c
- https://git.kernel.org/stable/c/46762cefe7f4e5bffc1eb467810a7bbb02e461d7
ADP enrichment
No English description supplied.
No references supplied.