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.