Description

In the Linux kernel, the following vulnerability has been resolved: slip: bound decode() reads against the compressed packet length slhc_uncompress() parses a VJ-compressed TCP header by advancing a pointer through the packet via decode() and pull16(). Neither helper bounds-checks against isize, and decode() masks its return with & 0xffff so it can never return the -1 that callers test for -- those error paths are dead code. A short compressed frame whose change byte requests optional fields lets decode() read past the end of the packet. The over-read bytes are folded into the cached cstate and reflected into subsequent reconstructed packets. Make decode() and pull16() take the packet end pointer and return -1 when exhausted. Add a bounds check before the TCP-checksum read. The existing == -1 tests now do what they were always meant to.

References 8

• git.kernel.org https://git.kernel.org/stable/c/0511ecb00e61bf28e2fec4bb41fcce385c3a3b2d
• git.kernel.org https://git.kernel.org/stable/c/335957df4ed60f02a2ec0432fbedbf0cc7241d8b
• git.kernel.org https://git.kernel.org/stable/c/37537e42e6df387398bee85cb85070cc80bb1e10
• git.kernel.org https://git.kernel.org/stable/c/4c1367a2d7aad643a6f87c6931b13cc1a25e8ca7
• git.kernel.org https://git.kernel.org/stable/c/4cefe32639933d652614b0bd50f818f9af4af78f
• git.kernel.org https://git.kernel.org/stable/c/6268f01ae989013671b526c883e92655342c6f6f
• git.kernel.org https://git.kernel.org/stable/c/9aafba2f49e1fcccc2018816f5836a609c925879
• git.kernel.org https://git.kernel.org/stable/c/d42bec6e4f6d6d658be365539400b3314b76b2a7

Remediation