[Bug] heap-overflow in get_ipv6_next

[kdsjZh]

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Describe the bug
There is a heap-overflow bug found in get_ipv6_next, can be triggered via tcprewrite + ASan

To Reproduce
Steps to reproduce the behavior:

1. export CC=clang && export CFLAGS="-fsanitize=address -g"
2. ./autogen.sh && ./configure --disable-shared --disable-local-libopts && make clean && make -j8
3. ./src/tcprewrite -o /dev/null -i POC
   output:

Warning: tcprewrite/crash.1 was captured using a snaplen of 64 bytes.  This may mean you have truncated packets.
=================================================================
==7944==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x7fc3f2e48820 at pc 0x000000535bca bp 0x7ffe1d7fcb70 sp 0x7ffe1d7fcb68
READ of size 4 at 0x7fc3f2e48820 thread T0
    #0 0x535bc9 in get_ipv6_next /benchmark/vulnerable/tcpreplay/src/common/get.c:679:14
    #1 0x53598e in get_layer4_v6 /benchmark/vulnerable/tcpreplay/src/common/get.c:626:22
    #2 0x4f9bc4 in tcpedit_packet /benchmark/vulnerable/tcpreplay/src/tcpedit/tcpedit.c:198:13
    #3 0x4f80fc in rewrite_packets /benchmark/vulnerable/tcpreplay/src/tcprewrite.c:304:22
    #4 0x4f7418 in main /benchmark/vulnerable/tcpreplay/src/tcprewrite.c:145:9

    #5 0x7fc3f175dbf6 in __libc_start_main /build/glibc-S9d2JN/glibc-2.27/csu/../csu/libc-start.c:310
    #6 0x41c2c9 in _start (/benchmark/vulnerable/tcpreplay/src/tcprewrite+0x41c2c9)

0x7fc3f2e48820 is located 10 bytes to the right of 262166-byte region [0x7fc3f2e08800,0x7fc3f2e48816)
allocated by thread T0 here:
    #0 0x4aec90 in malloc /home/nipc/workspace/install/llvm-project/llvm/projects/compiler-rt/lib/asan/asan_malloc_linux.cpp:145
    #1 0x536c1f in _our_safe_malloc /benchmark/vulnerable/tcpreplay/src/common/utils.c:50:16
    #2 0x4f7e02 in rewrite_packets /benchmark/vulnerable/tcpreplay/src/tcprewrite.c:267:34
    #3 0x4f7418 in main /benchmark/vulnerable/tcpreplay/src/tcprewrite.c:145:9
    #4 0x7fc3f175dbf6 in __libc_start_main /build/glibc-S9d2JN/glibc-2.27/csu/../csu/libc-start.c:310

SUMMARY: AddressSanitizer: heap-buffer-overflow /benchmark/vulnerable/tcpreplay/src/common/get.c:679:14 in get_ipv6_next
Shadow bytes around the buggy address:
  0x0ff8fe5c10b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0ff8fe5c10c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0ff8fe5c10d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0ff8fe5c10e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0ff8fe5c10f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0ff8fe5c1100: 00 00 06 fa[fa]fa fa fa fa fa fa fa fa fa fa fa
  0x0ff8fe5c1110: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0ff8fe5c1120: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0ff8fe5c1130: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0ff8fe5c1140: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0ff8fe5c1150: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07
  Heap left redzone:       fa
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
  Shadow gap:              cc
==7944==ABORTING

Screenshots

System (please complete the following information):

• OS: Ubuntu
• OS version : can be reproduced in 18.04/20.04
• clang version: 12.0.1 (release/12.x)
• Tcpreplay Version : latest commit 09f0774

Credit
Han Zheng
NCNIPC of China
Hexhive

POC
POC2.zip

[fklassen]

Improved overflow protection added in PR #740