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Date: Thu, 29 Nov 2018 10:18:18 +0100
From: Marcus Meissner <meissner@...e.de>
To: oss-security@...ts.openwall.com
Subject: Re: memory safety bugs in bc
Hi Hanno,
(FWIW)
Given Mitres guidance on "dcraw", as this is a standalone tool
and only denial of service attacks I do not see a need for CVEs.
Ciao, Marcus
On Wed, Nov 28, 2018 at 01:31:45PM +0100, Hanno Böck wrote:
> Hi,
>
> bc is a command line calculator that is commonly available on Linux
> systems.
>
> I reported various memory safety bugs and crashes a long time ago, some
> got also fixed but some more got ignored.
>
> (I'm aware it's debatable whether a tool like bc should be considered
> attack surface, as there are probably not many situations where it's fed
> attacker controlled input.)
>
>
> -----------------------------
>
> echo 'define p(a[],u){}p(a[],0,0)'|./bc
>
> Causes a heap out of bounds read, also segfaults without asan.
>
> ASAN stack trace:
>
> ==2068==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x6020000001e8 at pc 0x5593e5e43b32 bp 0x7fffa5908ed0 sp 0x7fffa5908ec0
> READ of size 8 at 0x6020000001e8 thread T0
> #0 0x5593e5e43b31 in process_params /mnt/ram/bc-1.07.1/bc/storage.c:1061
> #1 0x5593e5e39718 in execute /mnt/ram/bc-1.07.1/bc/execute.c:157
> #2 0x5593e5e44d26 in run_code /mnt/ram/bc-1.07.1/bc/util.c:295
> #3 0x5593e5e2df52 in yyparse ../../bc/bc.y:134
> #4 0x5593e5e2d0ea in main /mnt/ram/bc-1.07.1/bc/main.c:260
> #5 0x7f2b653a24ca in __libc_start_main (/lib64/libc.so.6+0x234ca)
> #6 0x5593e5e2c419 in _start (/mnt/ram/bc-1.07.1/bc/bc+0x9419)
>
> 0x6020000001e8 is located 8 bytes to the left of 16-byte region [0x6020000001f0,0x602000000200)
> allocated by thread T0 here:
> #0 0x7f2b65636b10 in malloc (/usr/lib/gcc/x86_64-pc-linux-gnu/8.2.0/libasan.so.5+0xedb10)
> #1 0x5593e5e46ac2 in bc_malloc /mnt/ram/bc-1.07.1/bc/util.c:652
> #2 0x5593e5e43c01 in nextarg /mnt/ram/bc-1.07.1/bc/util.c:58
> #3 0x5593e5e3e83a in load_code /mnt/ram/bc-1.07.1/bc/load.c:261
> #4 0x5593e5e44bf6 in generate /mnt/ram/bc-1.07.1/bc/util.c:277
> #5 0x5593e5e2fed8 in yyparse ../../bc/bc.y:352
> #6 0x5593e5e2d0ea in main /mnt/ram/bc-1.07.1/bc/main.c:260
> #7 0x7f2b653a24ca in __libc_start_main (/lib64/libc.so.6+0x234ca)
>
> -----------------------------
>
> echo -e 'define a(s,t){if(0)0}for(s=0;;){j(a(),0)}\ns'|./bc
>
> Causes a null pointer deref, also crashes without asan.
>
> ASAN trace:
> ==2091==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x56201e2aafc8 bp 0x7fffb04d6d60 sp 0x7fffb04d6d40 T0)
> ==2091==The signal is caused by a READ memory access.
> ==2091==Hint: address points to the zero page.
> #0 0x56201e2aafc7 in load_var /mnt/ram/bc-1.07.1/bc/storage.c:653
> #1 0x56201e2a37c7 in execute /mnt/ram/bc-1.07.1/bc/execute.c:324
> #2 0x56201e2add26 in run_code /mnt/ram/bc-1.07.1/bc/util.c:295
> #3 0x56201e296f52 in yyparse ../../bc/bc.y:134
> #4 0x56201e2960ea in main /mnt/ram/bc-1.07.1/bc/main.c:260
> #5 0x7fbdbe7124ca in __libc_start_main (/lib64/libc.so.6+0x234ca)
> #6 0x56201e295419 in _start (/mnt/ram/bc-1.07.1/bc/bc+0x9419)
>
> -----------------------------
>
> echo -e 'define t(x,y,d,s){f()}\ndefine f(){t()}\nfor(s=0;;){f()}\nfor(s=0;;){}' | ./bc
>
> null pointer read, but doesn't crash without asan.
>
> ==6340==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x55fdb8a43d49 bp 0x7fffae7307e0 sp 0x7fffae7307d0 T0)
> ==6340==The signal is caused by a READ memory access.
> ==6340==Hint: address points to the zero page.
> #0 0x55fdb8a43d48 in bc_free_num /mnt/ram/bc-1.07.1/lib/number.c:92
> #1 0x55fdb8a3d32a in store_var /mnt/ram/bc-1.07.1/bc/storage.c:461
> #2 0x55fdb8a368cf in execute /mnt/ram/bc-1.07.1/bc/execute.c:339
> #3 0x55fdb8a40d26 in run_code /mnt/ram/bc-1.07.1/bc/util.c:295
> #4 0x55fdb8a29f52 in yyparse ../../bc/bc.y:134
> #5 0x55fdb8a290ea in main /mnt/ram/bc-1.07.1/bc/main.c:260
> #6 0x7f763973b4ca in __libc_start_main (/lib64/libc.so.6+0x234ca)
> #7 0x55fdb8a28419 in _start (/mnt/ram/bc-1.07.1/bc/bc+0x9419)
>
> -----------------------------
>
> echo -e 'define t(x,y,d,s,t){if(0){}\nfor(;0<y;)f(0)}define f(x){(t())}for(s=0;;){t(0,1,0,0,0)}\nt()'|./bc
>
> null pointer read, but doesn't crash without asan.
>
> ==6365==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x55d4e78cfd9c bp 0x7ffc83b7d590 sp 0x7ffc83b7d560 T0)
> ==6365==The signal is caused by a READ memory access.
> ==6365==Hint: address points to the zero page.
> #0 0x55d4e78cfd9b in pop_vars /mnt/ram/bc-1.07.1/bc/storage.c:921
> #1 0x55d4e78c91e8 in execute /mnt/ram/bc-1.07.1/bc/execute.c:538
> #2 0x55d4e78d1d26 in run_code /mnt/ram/bc-1.07.1/bc/util.c:295
> #3 0x55d4e78baf52 in yyparse ../../bc/bc.y:134
> #4 0x55d4e78ba0ea in main /mnt/ram/bc-1.07.1/bc/main.c:260
> #5 0x7f9c3f6bb4ca in __libc_start_main (/lib64/libc.so.6+0x234ca)
> #6 0x55d4e78b9419 in _start (/mnt/ram/bc-1.07.1/bc/bc+0x9419)
>
> -----------------------------
>
> echo 'define m(x){for(;;)0}m(b[])'|./bc
>
> null pointer read, but doesn't crash without asan.
>
> ==6373==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x7f7fd8cdaec2 bp 0x7ffd4d86c230 sp 0x7ffd4d86b958 T0)
> ==6373==The signal is caused by a READ memory access.
> ==6373==Hint: address points to the zero page.
> #0 0x7f7fd8cdaec1 (/usr/lib/gcc/x86_64-pc-linux-gnu/8.2.0/libasan.so.5+0x108ec1)
> #1 0x7f7fd8c1f76c (/usr/lib/gcc/x86_64-pc-linux-gnu/8.2.0/libasan.so.5+0x4d76c)
> #2 0x7f7fd8c200a4 in __interceptor_vfprintf (/usr/lib/gcc/x86_64-pc-linux-gnu/8.2.0/libasan.so.5+0x4e0a4)
> #3 0x561fe31fc5e6 in rt_error /mnt/ram/bc-1.07.1/bc/util.c:788
> #4 0x561fe31f8aed in process_params /mnt/ram/bc-1.07.1/bc/storage.c:1050
> #5 0x561fe31ee718 in execute /mnt/ram/bc-1.07.1/bc/execute.c:157
> #6 0x561fe31f9d26 in run_code /mnt/ram/bc-1.07.1/bc/util.c:295
> #7 0x561fe31e2f52 in yyparse ../../bc/bc.y:134
> #8 0x561fe31e20ea in main /mnt/ram/bc-1.07.1/bc/main.c:260
> #9 0x7f7fd8a2b4ca in __libc_start_main (/lib64/libc.so.6+0x234ca)
> #10 0x561fe31e1419 in _start (/mnt/ram/bc-1.07.1/bc/bc+0x9419)
>
>
> --
> Hanno Böck
> https://hboeck.de/
>
> mail/jabber: hanno@...eck.de
> GPG: FE73757FA60E4E21B937579FA5880072BBB51E42
>
--
Marcus Meissner,SUSE LINUX GmbH; Maxfeldstrasse 5; D-90409 Nuernberg; Zi. 3.1-33,+49-911-740 53-432,,serv=loki,mail=wotan,type=real <meissner@...e.de>
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