Headline

CVE-2020-21684: Xfig / Tickets / #75 global-buffer-overflow in put_font at genpict2e.c:2229

A global buffer overflow in the put_font in genpict2e.c of fig2dev 3.2.7b allows attackers to cause a denial of service (DOS) via converting a xfig file into pict2e format.

3 years ago

CVE

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#dos #git #buffer_overflow

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Status: closed

Owner: nobody

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Updated: 2020-12-21

Created: 2019-12-28

Private: No

Hi,
I found a global-buffer-overflow in put_font at genpict2e.c:2229
Please run following command to reproduce it,

ASAN LOG

==36598==ERROR: AddressSanitizer: global-buffer-overflow on address 0x000000c4f858 at pc 0x0000007614d0 bp 0x7fff29528440 sp 0x7fff29528438 READ of size 8 at 0x000000c4f858 thread T0 #0 0x7614cf in put_font /home/tmp/mcj-fig2dev/fig2dev/dev/genpict2e.c:2229:7 #1 0x7614cf in genpict2e_text /home/tmp/mcj-fig2dev/fig2dev/dev/genpict2e.c:2278 #2 0x54b8bb in gendev_objects /home/tmp/mcj-fig2dev/fig2dev/fig2dev.c:1003:6 #3 0x54b8bb in main /home/tmp/mcj-fig2dev/fig2dev/fig2dev.c:480 #4 0x7fb82753eb96 in __libc_start_main /build/glibc-OTsEL5/glibc-2.27/csu/…/csu/libc-start.c:310 #5 0x41b3a9 in _start (/home/tmp/fig2dev+0x41b3a9)

0x000000c4f858 is located 8 bytes to the left of global variable ‘texfonts’ defined in ‘genpict2e.c:54:14’ (0xc4f860) of size 48 0x000000c4f858 is located 52 bytes to the right of global variable ‘default_color’ defined in ‘genpict2e.c:119:12’ (0xc4f820) of size 4 SUMMARY: AddressSanitizer: global-buffer-overflow /home/tmp/mcj-fig2dev/fig2dev/dev/genpict2e.c:2229:7 in put_font Shadow bytes around the buggy address: 0x000080181eb0: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 00 00 00 00 0x000080181ec0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x000080181ed0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x000080181ee0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x000080181ef0: 00 00 00 00 00 00 00 00 f9 f9 f9 f9 f9 f9 f9 f9 =>0x000080181f00: f9 f9 f9 f9 04 f9 f9 f9 f9 f9 f9[f9]00 00 00 00 0x000080181f10: 00 00 f9 f9 f9 f9 f9 f9 00 00 00 00 00 00 00 00 0x000080181f20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x000080181f30: 00 00 00 00 00 00 00 00 00 00 00 00 f9 f9 f9 f9 0x000080181f40: f9 f9 f9 f9 04 f9 f9 f9 f9 f9 f9 f9 04 f9 f9 f9 0x000080181f50: f9 f9 f9 f9 00 00 00 00 00 00 00 00 00 00 f9 f9 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 ==36598==ABORTING

fig2dev Version 3.2.7b
I also tested this in git Commit [3065ab] and can reproduce it.

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Commit: [3065ab]

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