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Buffer overflow in string_extract_double_quoted - subst.c
From: |
Eduardo A . Bustamante López |
Subject: |
Buffer overflow in string_extract_double_quoted - subst.c |
Date: |
Mon, 7 Jan 2019 02:02:24 -0800 |
User-agent: |
Mutt/1.10.1 (2018-07-13) |
Found by fuzzing `read -e' with AFL:
debian@debian-fuzz:/mnt$ cat -A dispose_word
"^[^EM-b^_M-u$$(M-J^^_^Q$
^[^E
debian@debian-fuzz:/mnt$ base64 < dispose_word
IhsF4h/1JCQoyl4fEQobBQ==
debian@debian-fuzz:/mnt$ LC_ALL=zh_CN.gbk ~/build-gdb/bash --noprofile --norc
-c 'PATH= read -e < dispose_word'
hi
"��$$(
TRACE: pid 15530: xparse_dolparen:0: base[5] != RPAREN (40), base = `"��$$(
'
TRACE: pid 15530: xparse_dolparen:0: *indp (5) < orig_ind (6), orig_string = `
'
malloc: ../bash-5.0-rc1/dispose_cmd.c:249: assertion botched
malloc: 0x55d956dc4de8: allocated: last allocated from
../bash-5.0-rc1/subst.c:866
free: start and end chunk sizes differ
Aborting...Aborted
(...)
Aborting...
Program received signal SIGABRT, Aborted.
__GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
50 ../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
(gdb) bt
#0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
#1 0x00007ffff7df4535 in __GI_abort () at abort.c:79
#2 0x00005555555b39b5 in programming_error (format=0x555555686bd8 "free: start
and end chunk sizes differ") at ../bash-5.0-rc1/error.c:175
#3 0x000055555566523d in xbotch (mem=0x555555765da8, e=8, s=0x555555686bd8
"free: start and end chunk sizes differ", file=0x55555566c268
"../bash-5.0-rc1/dispose_cmd.c", line=249)
at ../../../bash-5.0-rc1/lib/malloc/malloc.c:354
#4 0x000055555566648e in internal_free (mem=0x555555765da8,
file=0x55555566c268 "../bash-5.0-rc1/dispose_cmd.c", line=249, flags=1) at
../../../bash-5.0-rc1/lib/malloc/malloc.c:960
#5 0x0000555555667006 in sh_free (mem=0x555555765da8, file=0x55555566c268
"../bash-5.0-rc1/dispose_cmd.c", line=249) at
../../../bash-5.0-rc1/lib/malloc/malloc.c:1321
#6 0x00005555556001f4 in sh_xfree (string=0x555555765da8, file=0x55555566c268
"../bash-5.0-rc1/dispose_cmd.c", line=249) at ../bash-5.0-rc1/xmalloc.c:223
#7 0x000055555559d860 in dispose_word (w=0x555555761da8) at
../bash-5.0-rc1/dispose_cmd.c:249
#8 0x00005555555d6ef5 in expand_word_internal (word=0x555555761e08, quoted=0,
isexp=0, contains_dollar_at=0x0, expanded_something=0x0) at
../bash-5.0-rc1/subst.c:10189
#9 0x00005555555c84dd in call_expand_word_internal (w=0x555555761e08, q=0,
i=0, c=0x0, e=0x0) at ../bash-5.0-rc1/subst.c:3684
#10 0x00005555555c8b94 in expand_word (word=0x555555761e08, quoted=0) at
../bash-5.0-rc1/subst.c:3978
#11 0x00005555555f35b6 in shell_expand_line (count=1, ignore=5) at
../bash-5.0-rc1/bashline.c:2755
#12 0x0000555555639ed4 in _rl_dispatch_subseq (key=5, map=0x5555556ac220
<emacs_meta_keymap>, got_subseq=0) at
../../../bash-5.0-rc1/lib/readline/readline.c:852
#13 0x000055555563a399 in _rl_dispatch_subseq (key=27, map=0x5555556ab200
<emacs_standard_keymap>, got_subseq=0) at
../../../bash-5.0-rc1/lib/readline/readline.c:986
#14 0x0000555555639c4b in _rl_dispatch (key=-136275877, map=0x5555556ab200
<emacs_standard_keymap>) at ../../../bash-5.0-rc1/lib/readline/readline.c:798
#15 0x00005555556398ce in readline_internal_char () at
../../../bash-5.0-rc1/lib/readline/readline.c:632
#16 0x0000555555639929 in readline_internal_charloop () at
../../../bash-5.0-rc1/lib/readline/readline.c:659
#17 0x0000555555639949 in readline_internal () at
../../../bash-5.0-rc1/lib/readline/readline.c:671
#18 0x0000555555639367 in readline (prompt=0x555555680f84 "") at
../../../bash-5.0-rc1/lib/readline/readline.c:377
#19 0x0000555555611bcf in edit_line (p=0x555555680f84 "", itext=0x0) at
../../bash-5.0-rc1/builtins/../../bash-5.0-rc1/builtins/read.def:1107
#20 0x00005555556108f8 in read_builtin (list=0x0) at
../../bash-5.0-rc1/builtins/../../bash-5.0-rc1/builtins/read.def:566
#21 0x00005555555a5afa in execute_builtin (builtin=0x55555560fa73
<read_builtin>, words=0x555555761e68, flags=0, subshell=0) at
../bash-5.0-rc1/execute_cmd.c:4706
#22 0x00005555555a6aa2 in execute_builtin_or_function (words=0x555555761e68,
builtin=0x55555560fa73 <read_builtin>, var=0x0, redirects=0x555555761bc8,
fds_to_close=0x555555761ba8, flags=0)
at ../bash-5.0-rc1/execute_cmd.c:5214
#23 0x00005555555a5365 in execute_simple_command
(simple_command=0x555555761a88, pipe_in=-1, pipe_out=-1, async=0,
fds_to_close=0x555555761ba8) at ../bash-5.0-rc1/execute_cmd.c:4476
#24 0x000055555559e9f4 in execute_command_internal (command=0x555555761a48,
asynchronous=0, pipe_in=-1, pipe_out=-1, fds_to_close=0x555555761ba8) at
../bash-5.0-rc1/execute_cmd.c:842
#25 0x000055555560858a in parse_and_execute (string=0x555555761688 "PATH= read
-e < dispose_word", from_file=0x5555556690f0 "-c", flags=4) at
../../bash-5.0-rc1/builtins/evalstring.c:436
#26 0x000055555558564a in run_one_command (command=0x7fffffffe28c "PATH= read
-e < dispose_word") at ../bash-5.0-rc1/shell.c:1426
#27 0x0000555555584789 in main (argc=5, argv=0x7fffffffdfe8,
env=0x7fffffffe018) at ../bash-5.0-rc1/shell.c:741
(gdb) frame 7
#7 0x000055555559d860 in dispose_word (w=0x555555761da8) at
../bash-5.0-rc1/dispose_cmd.c:249
249 FREE (w->word);
(gdb) l
244 /* How to free a WORD_DESC. */
245 void
246 dispose_word (w)
247 WORD_DESC *w;
248 {
249 FREE (w->word);
250 ocache_free (wdcache, WORD_DESC, w);
251 }
252
253 /* Free a WORD_DESC, but not the word contained within. */
(gdb) p w
$1 = (WORD_DESC *) 0x555555761da8
(gdb) p *w
$2 = {word = 0x555555765da8 "��$$((\n", flags = 0}
Running it on an ASAN enabled bash:
debian@debian-fuzz:/mnt$ LC_ALL=zh_CN.gbk ~/build-asan/bash --noprofile --norc
-c 'PATH= read -e < dispose_word'
hi
"��$$(
TRACE: pid 29276: xparse_dolparen:0: base[5] != RPAREN (40), base = `"��$$(
'
TRACE: pid 29276: xparse_dolparen:0: *indp (5) < orig_ind (6), orig_string = `
'
=================================================================
==29276==ERROR: AddressSanitizer: heap-buffer-overflow on address
0x6020000055b7 at pc 0x00000061f92f bp 0x7ffcd0b6c5f0 sp 0x7ffcd0b6c5e8
WRITE of size 1 at 0x6020000055b7 thread T0
#0 0x61f92e in string_extract_double_quoted
/home/debian/build-asan/../bash-5.0-rc1/subst.c:995:11
#1 0x603b8e in expand_word_internal
/home/debian/build-asan/../bash-5.0-rc1/subst.c:10149:11
#2 0x5fb4a0 in call_expand_word_internal
/home/debian/build-asan/../bash-5.0-rc1/subst.c:3684:12
#3 0x608478 in expand_word
/home/debian/build-asan/../bash-5.0-rc1/subst.c:3978:13
#4 0x68b396 in shell_expand_line
/home/debian/build-asan/../bash-5.0-rc1/bashline.c:2755:25
#5 0x769abd in _rl_dispatch_subseq
/home/debian/build-asan/lib/readline/../../../bash-5.0-rc1/lib/readline/readline.c:852:8
#6 0x76a76e in _rl_dispatch_subseq
/home/debian/build-asan/lib/readline/../../../bash-5.0-rc1/lib/readline/readline.c:986:8
#7 0x76899a in _rl_dispatch
/home/debian/build-asan/lib/readline/../../../bash-5.0-rc1/lib/readline/readline.c:798:10
#8 0x76882f in readline_internal_char
/home/debian/build-asan/lib/readline/../../../bash-5.0-rc1/lib/readline/readline.c:632:11
#9 0x76ce7f in readline_internal_charloop
/home/debian/build-asan/lib/readline/../../../bash-5.0-rc1/lib/readline/readline.c:659:11
#10 0x76789d in readline_internal
/home/debian/build-asan/lib/readline/../../../bash-5.0-rc1/lib/readline/readline.c:671:19
#11 0x7676ba in readline
/home/debian/build-asan/lib/readline/../../../bash-5.0-rc1/lib/readline/readline.c:377:11
#12 0x6fe637 in edit_line
/home/debian/build-asan/builtins/../../bash-5.0-rc1/builtins/../../bash-5.0-rc1/builtins/read.def:1107:9
#13 0x6fa7d5 in read_builtin
/home/debian/build-asan/builtins/../../bash-5.0-rc1/builtins/../../bash-5.0-rc1/builtins/read.def:566:16
#14 0x592620 in execute_builtin
/home/debian/build-asan/../bash-5.0-rc1/execute_cmd.c:4706:13
#15 0x5910a7 in execute_builtin_or_function
/home/debian/build-asan/../bash-5.0-rc1/execute_cmd.c:5214:14
#16 0x579877 in execute_simple_command
/home/debian/build-asan/../bash-5.0-rc1/execute_cmd.c:4476:13
#17 0x5701d2 in execute_command_internal
/home/debian/build-asan/../bash-5.0-rc1/execute_cmd.c:842:4
#18 0x6dd393 in parse_and_execute
/home/debian/build-asan/builtins/../../bash-5.0-rc1/builtins/evalstring.c:436:17
#19 0x51d4f4 in run_one_command
/home/debian/build-asan/../bash-5.0-rc1/shell.c:1426:12
#20 0x518ec9 in main /home/debian/build-asan/../bash-5.0-rc1/shell.c:741:7
#21 0x7f697e24009a in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x2409a)
#22 0x43fa39 in _start (/home/debian/build-asan/bash+0x43fa39)
0x6020000055b7 is located 0 bytes to the right of 7-byte region
[0x6020000055b0,0x6020000055b7)
allocated by thread T0 here:
#0 0x4e7883 in malloc (/home/debian/build-asan/bash+0x4e7883)
#1 0x6c2aa0 in xmalloc
/home/debian/build-asan/../bash-5.0-rc1/xmalloc.c:114:10
#2 0x61e905 in string_extract_double_quoted
/home/debian/build-asan/../bash-5.0-rc1/subst.c:866:18
#3 0x603b8e in expand_word_internal
/home/debian/build-asan/../bash-5.0-rc1/subst.c:10149:11
#4 0x5fb4a0 in call_expand_word_internal
/home/debian/build-asan/../bash-5.0-rc1/subst.c:3684:12
#5 0x608478 in expand_word
/home/debian/build-asan/../bash-5.0-rc1/subst.c:3978:13
#6 0x68b396 in shell_expand_line
/home/debian/build-asan/../bash-5.0-rc1/bashline.c:2755:25
#7 0x769abd in _rl_dispatch_subseq
/home/debian/build-asan/lib/readline/../../../bash-5.0-rc1/lib/readline/readline.c:852:8
#8 0x76a76e in _rl_dispatch_subseq
/home/debian/build-asan/lib/readline/../../../bash-5.0-rc1/lib/readline/readline.c:986:8
#9 0x76899a in _rl_dispatch
/home/debian/build-asan/lib/readline/../../../bash-5.0-rc1/lib/readline/readline.c:798:10
#10 0x76882f in readline_internal_char
/home/debian/build-asan/lib/readline/../../../bash-5.0-rc1/lib/readline/readline.c:632:11
#11 0x76ce7f in readline_internal_charloop
/home/debian/build-asan/lib/readline/../../../bash-5.0-rc1/lib/readline/readline.c:659:11
#12 0x76789d in readline_internal
/home/debian/build-asan/lib/readline/../../../bash-5.0-rc1/lib/readline/readline.c:671:19
#13 0x7676ba in readline
/home/debian/build-asan/lib/readline/../../../bash-5.0-rc1/lib/readline/readline.c:377:11
#14 0x6fe637 in edit_line
/home/debian/build-asan/builtins/../../bash-5.0-rc1/builtins/../../bash-5.0-rc1/builtins/read.def:1107:9
#15 0x6fa7d5 in read_builtin
/home/debian/build-asan/builtins/../../bash-5.0-rc1/builtins/../../bash-5.0-rc1/builtins/read.def:566:16
#16 0x592620 in execute_builtin
/home/debian/build-asan/../bash-5.0-rc1/execute_cmd.c:4706:13
#17 0x5910a7 in execute_builtin_or_function
/home/debian/build-asan/../bash-5.0-rc1/execute_cmd.c:5214:14
#18 0x579877 in execute_simple_command
/home/debian/build-asan/../bash-5.0-rc1/execute_cmd.c:4476:13
#19 0x5701d2 in execute_command_internal
/home/debian/build-asan/../bash-5.0-rc1/execute_cmd.c:842:4
#20 0x6dd393 in parse_and_execute
/home/debian/build-asan/builtins/../../bash-5.0-rc1/builtins/evalstring.c:436:17
#21 0x51d4f4 in run_one_command
/home/debian/build-asan/../bash-5.0-rc1/shell.c:1426:12
#22 0x518ec9 in main /home/debian/build-asan/../bash-5.0-rc1/shell.c:741:7
#23 0x7f697e24009a in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x2409a)
SUMMARY: AddressSanitizer: heap-buffer-overflow
/home/debian/build-asan/../bash-5.0-rc1/subst.c:995:11 in
string_extract_double_quoted
Shadow bytes around the buggy address:
0x0c047fff8a60: fa fa fd fa fa fa fd fa fa fa fd fa fa fa fd fa
0x0c047fff8a70: fa fa 00 07 fa fa 01 fa fa fa fd fa fa fa fd fa
0x0c047fff8a80: fa fa fd fa fa fa fd fa fa fa fd fa fa fa fd fa
0x0c047fff8a90: fa fa fd fa fa fa fd fa fa fa fd fa fa fa fd fa
0x0c047fff8aa0: fa fa fd fa fa fa fd fa fa fa fd fa fa fa fd fa
=>0x0c047fff8ab0: fa fa 00 fa fa fa[07]fa fa fa fd fd fa fa 03 fa
0x0c047fff8ac0: fa fa fd fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8ad0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8ae0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8af0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8b00: 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
==29276==ABORTING
Ooops:
debian@debian-fuzz:/mnt$ cat -n /home/debian/build-asan/../bash-5.0-rc1/subst.c
| sed -n '990,997p'
990 continue;
991 }
992
993 break;
994 }
995 temp[j] = '\0';
996
997 /* Point to after the closing quote. */
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Eduardo A . Bustamante López <=