URL: https://code.wireshark.org/review/gitweb?p=wireshark.git;a=commit;h=c280333ba6027323de71ae655e8ea12563bdb69a
Submitter: Guy Harris (guy@xxxxxxxxxxxx)
Changed: branch: master-2.6
Repository: wireshark
Commits:
c280333 by Darius Davis (darius@xxxxxxxxxx):
BGP: Validate length of Path Attribute records.
Bug 13741 showed a case where the BGP dissector's failure to validate the
length of the Path Attribute record allowed a pathological BGP UPDATE packet to
generate more than one million items in the protocol tree by repeatedly
dissecting certain segments of the packet.
It's easy enough to detect when the Path Attribute length cannot be valid, so
let's do so. When the condition arises, let's raise an Expert Info error in
the same style and format as used elsewhere in the same routine, and abandon
dissection of the Path Attributes list.
With this check in place, an incorrect length computation is revealed at a
callsite. This would only have prevented a small (less than 5 bytes) Path
Attribute from being dissected if it was at the very end of the Path Attributes
list, but the bounds checking added in this change makes this problem much more
apparent, so we fix the length computation while we're here.
Testing Done: Built wireshark on Linux amd64. Using bgp.pcap from the Sample
Captures page on the wiki, verified that the dissection of the UPDATE
packets were unaltered by this fix. Using the capture attached to bug 13741
(clusterfuzz-testcase-minimized-6689222578667520.pcap), verified that the
packet no longer triggers the "too many items" exception, instead we see
an Expert Info for each oversized Path Attribute length, and eventually an
exception for "length of contained item exceeds length of containing item".
30,000 iterations of fuzz test with bgp.pcap as input, and many iterations
of randpkt-test too. Crafted a packet with a 3-byte ATOMIC_AGGREGATE Path
Attribute at the end of the Path Attributes list; Before this change, an
exception is raised during dissection, but after this change it is dissected
correctly.
Bug: 13741
Change-Id: I80f506b114a61e5b060d93b59bed6b94fb188b3e
Reviewed-on: https://code.wireshark.org/review/27466
Reviewed-by: Peter Wu <peter@xxxxxxxxxxxxx>
Petri-Dish: Peter Wu <peter@xxxxxxxxxxxxx>
Tested-by: Petri Dish Buildbot
Reviewed-by: Anders Broman <a.broman58@xxxxxxxxx>
(cherry picked from commit 6e88943d0eabc8c8bc11334ba4213ec64129575c)
Reviewed-on: https://code.wireshark.org/review/28401
Reviewed-by: Guy Harris <guy@xxxxxxxxxxxx>
Actions performed:
from dbd2cd6 Set libwscodecs.so's version to 2.0.0
adds c280333 BGP: Validate length of Path Attribute records.
Summary of changes:
epan/dissectors/packet-bgp.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)