[ovs-git] [openvswitch/ovs] 8ce8dc: ofp-actions: Fix use-after-free while decoding RAW...

Ilya Maximets noreply at github.com
Wed Feb 17 15:47:56 UTC 2021


  Branch: refs/heads/branch-2.14
  Home:   https://github.com/openvswitch/ovs
  Commit: 8ce8dc34b5f73b30ce0c1869af9947013c3c6575
      https://github.com/openvswitch/ovs/commit/8ce8dc34b5f73b30ce0c1869af9947013c3c6575
  Author: Ilya Maximets <i.maximets at ovn.org>
  Date:   2021-02-17 (Wed, 17 Feb 2021)

  Changed paths:
    M lib/ofp-actions.c
    M tests/automake.mk
    M tests/fuzz-regression-list.at
    A tests/fuzz-regression/ofp_print_fuzzer-6540965472632832

  Log Message:
  -----------
  ofp-actions: Fix use-after-free while decoding RAW_ENCAP.

While decoding RAW_ENCAP action, decode_ed_prop() might re-allocate
ofpbuf if there is no enough space left.  However, function
'decode_NXAST_RAW_ENCAP' continues to use old pointer to 'encap'
structure leading to write-after-free and incorrect decoding.

  ==3549105==ERROR: AddressSanitizer: heap-use-after-free on address
  0x60600000011a at pc 0x0000005f6cc6 bp 0x7ffc3a2d4410 sp 0x7ffc3a2d4408
  WRITE of size 2 at 0x60600000011a thread T0
    #0 0x5f6cc5 in decode_NXAST_RAW_ENCAP lib/ofp-actions.c:4461:20
    #1 0x5f0551 in ofpact_decode ./lib/ofp-actions.inc2:4777:16
    #2 0x5ed17c in ofpacts_decode lib/ofp-actions.c:7752:21
    #3 0x5eba9a in ofpacts_pull_openflow_actions__ lib/ofp-actions.c:7791:13
    #4 0x5eb9fc in ofpacts_pull_openflow_actions lib/ofp-actions.c:7835:12
    #5 0x64bb8b in ofputil_decode_packet_out lib/ofp-packet.c:1113:17
    #6 0x65b6f4 in ofp_print_packet_out lib/ofp-print.c:148:13
    #7 0x659e3f in ofp_to_string__ lib/ofp-print.c:1029:16
    #8 0x659b24 in ofp_to_string lib/ofp-print.c:1244:21
    #9 0x65a28c in ofp_print lib/ofp-print.c:1288:28
    #10 0x540d11 in ofctl_ofp_parse utilities/ovs-ofctl.c:2814:9
    #11 0x564228 in ovs_cmdl_run_command__ lib/command-line.c:247:17
    #12 0x56408a in ovs_cmdl_run_command lib/command-line.c:278:5
    #13 0x5391ae in main utilities/ovs-ofctl.c:179:9
    #14 0x7f6911ce9081 in __libc_start_main (/lib64/libc.so.6+0x27081)
    #15 0x461fed in _start (utilities/ovs-ofctl+0x461fed)

Fix that by getting a new pointer before using.

Credit to OSS-Fuzz.

Fuzzer regression test will fail only with AddressSanitizer enabled.

Reported-at: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=27851
Fixes: f839892a206a ("OF support and translation of generic encap and decap")
Acked-by: William Tu <u9012063 at gmail.com>
Signed-off-by: Ilya Maximets <i.maximets at ovn.org>




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