On 04/20/2018 06:57 AM, Jann Horn wrote: > The old code reads the "opsize" variable from out-of-bounds memory (first > byte behind the segment) if a broken TCP segment ends directly after an > opcode that is neither EOL nor NOP. > > The result of the read isn't used for anything, so the worst thing that > could theoretically happen is a pagefault; and since the physmap is usually > mostly contiguous, even that seems pretty unlikely. >
No page fault possible, because tcp headers are in skb->head And we have 'struct skb_shared_info' at the end of skb->head anyway. But, yes, reading some extra bytes with random content is possible.
