Description

In the Linux kernel, the following vulnerability has been resolved: batman-adv: fix fragment reassembly length accounting batman-adv keeps a running payload length for queued fragments and uses it to validate a fragment chain before reassembly. That accounting currently allows the accumulated fragment length to be truncated during updates. As a result, malformed fragment chains can bypass the intended validation and drive reassembly with inconsistent length state, leading to a local denial of service. Fix the accounting by storing the accumulated length in a length-typed field and rejecting update overflows before the existing validation logic runs. The fix was verified against the original reproducer and against valid fragment reassembly paths.

References 8

• git.kernel.org https://git.kernel.org/stable/c/37be61825b15534a16ff9cfc9546de155b6df982
• git.kernel.org https://git.kernel.org/stable/c/3eb8bcb823391bd58997831b3c9c152a4ba8e255
• git.kernel.org https://git.kernel.org/stable/c/975563c5de1123dde1ec7946bf5556d20c89d74e
• git.kernel.org https://git.kernel.org/stable/c/9cd3f16c320bfdadd4509358122368deb56a5741
• git.kernel.org https://git.kernel.org/stable/c/e4f3f6b818aa6a678bc54a2d4e0bece2303c6a64
• git.kernel.org https://git.kernel.org/stable/c/e910dbf509125fe51ad68e4fa74dc8ab0a8e787a
• git.kernel.org https://git.kernel.org/stable/c/f653b040dad1af70fa5cd4fe085e4758925480c9
• git.kernel.org https://git.kernel.org/stable/c/fdb2c96efb2baeb3725e9ce3ede8f1e36f5490f0

Remediation