Messages in this thread | | | Date | Wed, 18 Jul 2018 07:13:21 +0200 | From | Dominique Martinet <> | Subject | Re: [V9fs-developer] [PATCH] p9_parse_header() validate PDU length |
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Tomas Bortoli wrote on Thu, Jul 12, 2018: > This patch adds checks to the p9_parse_header() function to > verify that the length found within the header coincides with the actual > length of the PDU. Furthermore, it checks that the length stays within the > acceptable range. To do this the patch brings the actual length of the PDU > from the different transport layers (rdma and virtio). For TCP (trans_fd.c) > the length is not know before, so we get it from the header but we check it > anyway that it's within the valid range. > > Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com> > Reported-by: syzbot+65c6b72f284a39d416b4@syzkaller.appspotmail.com > --- > [..] > @@ -498,6 +489,21 @@ p9_parse_header(struct p9_fcall *pdu, int32_t *size, int8_t *type, int16_t *tag, > if (size) > *size = r_size; > > + if (pdu->size != r_size) { > + err = -EINVAL; > + goto rewind_and_exit; > + } > + if (pdu->size >= pdu->capacity || pdu->size < 7) { > + p9_debug(P9_DEBUG_ERROR, > + "requested packet size too big or too small: %d\n", > + pdu->size); > + return -EIO; > + }
Actually, I've been bad advice - this breaks on virtio with zc packets - a read or ls in a big directory fails with this in dmesg [ 1006.853775] 9pnet: -- p9_parse_header (17123): requested packet size too big or too small: 4306 [ 1006.853780] 9pnet: -- p9_check_zc_errors (17123): couldn't parse header -5
I haven't given this any thought yet, but dropping the patch for now
-- Dominique
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