CVE-2021-44925: Null Pointer Dereference in gf_svg_get_attribute_name() · Issue #1967 · gpac/gpac

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A null pointer dereference was discovered in gf_svg_get_attribute_name(). The vulnerability causes a segmentation fault and application crash.

Version:

MP4Box - GPAC version 1.1.0-DEV-revUNKNOWN_REV
(c) 2000-2021 Telecom Paris distributed under LGPL v2.1+ - http://gpac.io

Please cite our work in your research:
        GPAC Filters: https://doi.org/10.1145/3339825.3394929
        GPAC: https://doi.org/10.1145/1291233.1291452

GPAC Configuration:
Features: GPAC_CONFIG_LINUX GPAC_64_BITS GPAC_HAS_IPV6 GPAC_HAS_SOCK_UN GPAC_MINIMAL_ODF GPAC_HAS_QJS GPAC_HAS_JPEG GPAC_HAS_PNG GPAC_HAS_LINUX_DVB  GPAC_DISABLE_3D

System information
Ubuntu 20.04 focal, AMD EPYC 7742 64-Core @ 16x 2.25GHz

command:

poc_4.zip

Result

[iso file] extra box maxr found in hinf, deleting
[iso file] extra box maxr found in hinf, deleting
[iso file] Unknown box type 80rak in parent moov
[iso file] Incomplete box mdat - start 11495 size 796312
[iso file] Incomplete file while reading for dump - aborting parsing
[iso file] extra box maxr found in hinf, deleting
[iso file] extra box maxr found in hinf, deleting
[iso file] Unknown box type 80rak in parent moov
[iso file] Incomplete box mdat - start 11495 size 796312
[iso file] Incomplete file while reading for dump - aborting parsing
MPEG-4 LASeR Scene Parsing
Scene loaded - dumping 1 systems streams
[1]    3570050 segmentation fault  ./MP4Box -lsr ./poc/poc_4

gdb

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff78e16ac in gf_svg_get_attribute_name () from /root/fuckit/test/gpac1210/bin/gcc/libgpac.so.10
LEGEND: STACK | HEAP | CODE | DATA | RWX | RODATA
────────────────────────────────────────────[ REGISTERS ]─────────────────────────────────────────────
 RAX  0x0
 RBX  0x5555555decb0 —▸ 0x5555555d4350 ◂— 0x0
 RCX  0x0
 RDX  0x7ffff7f7c428 (xml_elements+8) ◂— 0x300000422
 RDI  0x0
 RSI  0x0
 R8   0x0
 R9   0xa
 R10  0x7ffff7e45bd4 ◂— 0x6e696f7020002022 /* '" ' */
 R11  0x7fffffff6ee7 ◂— 0xbffcbef5d8160036 /* '6' */
 R12  0x5555555df180 —▸ 0x5555555d4350 ◂— 0x0
 R13  0x0
 R14  0x7ffff7e10cf4 ◂— 'textContent'
 R15  0x7ffff7df5e9b ◂— 0x663325002f2e2e00
 RBP  0x7fffffff7080 ◂— 0x344e /* 'N4' */
 RSP  0x7fffffff6fe0 ◂— 0x25286574616c736e ('nslate(%')
 RIP  0x7ffff78e16ac (gf_svg_get_attribute_name+28) ◂— mov    rax, qword ptr [rdi]
──────────────────────────────────────────────[ DISASM ]──────────────────────────────────────────────
 ► 0x7ffff78e16ac <gf_svg_get_attribute_name+28>    mov    rax, qword ptr [rdi]
   0x7ffff78e16af <gf_svg_get_attribute_name+31>    movzx  ecx, word ptr [rax]
   0x7ffff78e16b2 <gf_svg_get_attribute_name+34>    xor    eax, eax
   0x7ffff78e16b4 <gf_svg_get_attribute_name+36>    cmp    cx, 0x408
   0x7ffff78e16b9 <gf_svg_get_attribute_name+41>    jne    gf_svg_get_attribute_name+64
 <gf_svg_get_attribute_name+64>
    ↓
   0x7ffff78e16d0 <gf_svg_get_attribute_name+64>    cmp    dword ptr [rdx], ecx
   0x7ffff78e16d2 <gf_svg_get_attribute_name+66>    jne    gf_svg_get_attribute_name+48
 <gf_svg_get_attribute_name+48>
    ↓
   0x7ffff78e16c0 <gf_svg_get_attribute_name+48>    add    eax, 1
   0x7ffff78e16c3 <gf_svg_get_attribute_name+51>    add    rdx, 0x10
   0x7ffff78e16c7 <gf_svg_get_attribute_name+55>    cmp    eax, 0x4e
   0x7ffff78e16ca <gf_svg_get_attribute_name+58>    je     gf_svg_get_attribute_name+365
  <gf_svg_get_attribute_name+365>
──────────────────────────────────────────────[ STACK ]───────────────────────────────────────────────
00:0000│ rsp 0x7fffffff6fe0 ◂— 0x25286574616c736e ('nslate(%')
01:0008│     0x7fffffff6fe8 —▸ 0x5555555decb0 —▸ 0x5555555d4350 ◂— 0x0
02:0010│     0x7fffffff6ff0 —▸ 0x7fffffff7080 ◂— 0x344e /* 'N4' */
03:0018│     0x7fffffff6ff8 —▸ 0x5555555df180 —▸ 0x5555555d4350 ◂— 0x0
04:0020│     0x7fffffff7000 —▸ 0x5555555df2e0 ◂— 0x0
05:0028│     0x7fffffff7008 —▸ 0x7ffff7e10cf4 ◂— 'textContent'
06:0030│     0x7fffffff7010 —▸ 0x7ffff7df5e9b ◂— 0x663325002f2e2e00
07:0038│     0x7fffffff7018 —▸ 0x7ffff7abae7a (DumpLSRAddReplaceInsert+938) ◂— mov    r14, rax
────────────────────────────────────────────[ BACKTRACE ]─────────────────────────────────────────────
 ► f 0   0x7ffff78e16ac gf_svg_get_attribute_name+28
   f 1   0x7ffff7abae7a DumpLSRAddReplaceInsert+938
   f 2   0x7ffff7abb12b gf_sm_dump_command_list+219
   f 3   0x7ffff7ac254c gf_sm_dump+1116
   f 4   0x555555584418 dump_isom_scene+616
   f 5   0x55555557b42c mp4boxMain+9228
   f 6   0x7ffff75630b3 __libc_start_main+243
──────────────────────────────────────────────────────────────────────────────────────────────────────
pwndbg> bt
#0  0x00007ffff78e16ac in gf_svg_get_attribute_name () from /root/fuckit/test/gpac1210/bin/gcc/libgpac.so.10
#1  0x00007ffff7abae7a in DumpLSRAddReplaceInsert () from /root/fuckit/test/gpac1210/bin/gcc/libgpac.so.10
#2  0x00007ffff7abb12b in gf_sm_dump_command_list () from /root/fuckit/test/gpac1210/bin/gcc/libgpac.so.10
#3  0x00007ffff7ac254c in gf_sm_dump () from /root/fuckit/test/gpac1210/bin/gcc/libgpac.so.10
#4  0x0000555555584418 in dump_isom_scene ()
#5  0x000055555557b42c in mp4boxMain ()
#6  0x00007ffff75630b3 in __libc_start_main (main=0x55555556c420 <main>, argc=3, argv=0x7fffffffe188, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffffffe178) at ../csu/libc-start.c:308
#7  0x000055555556c45e in _start ()