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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 williamtu#1 0x5f0551 in ofpact_decode ./lib/ofp-actions.inc2:4777:16 williamtu#2 0x5ed17c in ofpacts_decode lib/ofp-actions.c:7752:21 williamtu#3 0x5eba9a in ofpacts_pull_openflow_actions__ lib/ofp-actions.c:7791:13 williamtu#4 0x5eb9fc in ofpacts_pull_openflow_actions lib/ofp-actions.c:7835:12 williamtu#5 0x64bb8b in ofputil_decode_packet_out lib/ofp-packet.c:1113:17 williamtu#6 0x65b6f4 in ofp_print_packet_out lib/ofp-print.c:148:13 williamtu#7 0x659e3f in ofp_to_string__ lib/ofp-print.c:1029:16 williamtu#8 0x659b24 in ofp_to_string lib/ofp-print.c:1244:21 williamtu#9 0x65a28c in ofp_print lib/ofp-print.c:1288:28 williamtu#10 0x540d11 in ofctl_ofp_parse utilities/ovs-ofctl.c:2814:9 williamtu#11 0x564228 in ovs_cmdl_run_command__ lib/command-line.c:247:17 williamtu#12 0x56408a in ovs_cmdl_run_command lib/command-line.c:278:5 williamtu#13 0x5391ae in main utilities/ovs-ofctl.c:179:9 williamtu#14 0x7f6911ce9081 in __libc_start_main (/lib64/libc.so.6+0x27081) williamtu#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: f839892 ("OF support and translation of generic encap and decap") Acked-by: William Tu <u9012063@gmail.com> Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
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