Messages in this thread | | | Subject | Re: triggered 2.2.1 kernel panic in ppp | Date | Tue, 16 Feb 1999 10:51:17 +0200 (EET) | From | Matti Aarnio <> |
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a sun <asun@saul7.u.washington.edu> writes: > hi all, > > i was finally able to trigger a ppp bug that's plagued me sporadically > and inconsistently. it turns out the following is happening (which > explains the difficulty in repeating it): > 1) linux gets a vj compressed packet > 2) it calls rcv_proto_vjc_comp() (line 2050 in ppp.c) > 3) for certain packets, slhc_uncompress() returns an > uncompressed frame < compressed one. as a result, > skb->len > new_count + PPP_HDRLEN (by 7 bytes) > 4) pow! skb_put() dies horribly. > > before i stick in the obvious patch, i just want to make sure that > it's valid to have uncompressed packets smaller than the corresponding > compressed ones.
Yes, no matter what the compression algorithm, there will always be data blocks which it can't compress at all. All algorithms will always add some book-keeping stuff of their own into the resulting datastream, and thus the input data will be wrapped into such markers -- enlarging it.
I bet you have been moving some compressed data (GZIP, BZIP2, GIF, JPEG) while that did hit ?
> -a > asun@u.washington.edu
/Matti Aarnio <matti.aarnio@sonera.fi>
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