Description

In the Linux kernel, the following vulnerability has been resolved: batman-adv: fix tp_meter counter underflow during shutdown batadv_tp_sender_shutdown() unconditionally decrements the "sending" atomic counter. If multiple paths (e.g. timeout, user cancel, and normal finish) call this function, the counter can underflow to -1. Since the sender logic treats any non-zero value as "still sending", a negative value causes the sender kthread to loop indefinitely. This leads to a use-after-free when the interface is removed while the zombie thread is still active. Fix this by using atomic_xchg() to ensure the counter only transitions from 1 to 0 once. [sven: added missing change in batadv_tp_send]

References 8

• git.kernel.org https://git.kernel.org/stable/c/01cefc5923889e29dbb5f281c3d457714ceb9c00
• git.kernel.org https://git.kernel.org/stable/c/90ae3eae06b7b8ab9f6250b9497c860915b4c17b
• git.kernel.org https://git.kernel.org/stable/c/94f3b133168d1c49895e7cc6afbcf1cc0b354602
• git.kernel.org https://git.kernel.org/stable/c/abae88fa254f2981d39ac003a7b302528a22af64
• git.kernel.org https://git.kernel.org/stable/c/aeae11c5dad9cd0d50723890bdd866f8e6db2e7d
• git.kernel.org https://git.kernel.org/stable/c/c1bac194733aabd731aafa6a01350c229e187dba
• git.kernel.org https://git.kernel.org/stable/c/c66d20a3ff095e3f000551d208ec2606616db15c
• git.kernel.org https://git.kernel.org/stable/c/e75e2ab463b5b34df6b98f94d740aff327ce9f6b

Remediation