Messages in this thread | | | Subject | Re: [PATCH net] tcp: don't read out-of-bounds opsize | From | Eric Dumazet <> | Date | Fri, 20 Apr 2018 07:21:35 -0700 |
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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.
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