GNU bug report logs - #47412
env: fragile argument parsing

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Frank Busse <f.busse <at> imperial.ac.uk>
To: bug-coreutils <at> gnu.org
Subject: env: fragile argument parsing
Date: Fri, 26 Mar 2021 15:00:17 +0000

Hi,


env crashes for some nonsensical command line arguments (reported by
KLEE), e.g.:

---
> python3 -c "import os; os.execl('./src/env', 'env', b'--s=\"\"\t\x0b')"

=================================================================
==140651==ERROR: AddressSanitizer: heap-buffer-overflow on address
0x603000000028 at pc 0x562e1cc1078a bp 0x7ffd59964dd0 sp 0x7ffd59964dc0
WRITE of size 8 at 0x603000000028 thread T0
 #0 0x562e1cc10789 in build_argv src/env.c:511
 #1 0x562e1cc10982 in parse_split_string src/env.c:548
 #2 0x562e1cc127bc in main src/env.c:849
 #3 0x7f1c167e3b24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
 #4 0x562e1cc0e54d in _start (coreutils-8.32/src/env+0x654d)

0x603000000028 is located 0 bytes to the right of 24-byte region
[0x603000000010,0x603000000028)
allocated by thread T0 here:
 #0 0x7f1c16a3b459 in __interceptor_malloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:145
 #1 0x562e1cc19463 in xmalloc lib/xmalloc.c:41
 #2 0x562e1cc0ff54 in build_argv src/env.c:404
 #3 0x562e1cc10982 in parse_split_string src/env.c:548
 #4 0x562e1cc127bc in main src/env.c:849
 #5 0x7f1c167e3b24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)

SUMMARY: AddressSanitizer: heap-buffer-overflow src/env.c:511 in build_argv
---

or

---
> python3 -c "import os; os.execl('./src/env', 'env', b'--s=\xff \r\x0b\t\x0b-')"

=================================================================
==140886==ERROR: AddressSanitizer: heap-buffer-overflow on address
0x603000000030 at pc 0x55821372878a bp 0x7ffdd6e4bc40 sp 0x7ffdd6e4bc30
WRITE of size 8 at 0x603000000030 thread T0
 #0 0x558213728789 in build_argv src/env.c:511
 #1 0x558213728982 in parse_split_string src/env.c:548
 #2 0x55821372a7bc in main src/env.c:849
 #3 0x7f5b05ec5b24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
 #4 0x55821372654d in _start (coreutils-8.32/src/env+0x654d)

0x603000000030 is located 0 bytes to the right of 32-byte region
[0x603000000010,0x603000000030) allocated by thread T0 here:
 #0 0x7f5b0611d459 in __interceptor_malloc/build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:145
 #1 0x558213731463 in xmalloc lib/xmalloc.c:41
 #2 0x558213727f54 in build_argv src/env.c:404
 #3 0x558213728982 in parse_split_string src/env.c:548
 #4 0x55821372a7bc in main src/env.c:849
 #5 0x7f5b05ec5b24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)

SUMMARY: AddressSanitizer: heap-buffer-overflow src/env.c:511 in build_argv
---


Version: 8.32
Configure: CFLAGS="-ggdb -O0 -fsanitize=address" ./configure --without-selinux --without-gmp --disable-acl --disable-largefile --disable-libsmack --disable-xattr --disable-libcap --disable-nls


Kind regards,

Frank

Message #8 received at 47412 <at> debbugs.gnu.org (full text, mbox):

From: Pádraig Brady <P <at> draigBrady.com>
To: Frank Busse <f.busse <at> imperial.ac.uk>, 47412 <at> debbugs.gnu.org
Subject: Re: bug#47412: env: fragile argument parsing
Date: Fri, 26 Mar 2021 20:12:53 +0000

On 26/03/2021 15:00, Frank Busse wrote:
> Hi,
> 
> 
> env crashes for some nonsensical command line arguments (reported by
> KLEE), e.g.:
> 
> ---
>> python3 -c "import os; os.execl('./src/env', 'env', b'--s=\"\"\t\x0b')"
> 
> =================================================================
> ==140651==ERROR: AddressSanitizer: heap-buffer-overflow on address
> 0x603000000028 at pc 0x562e1cc1078a bp 0x7ffd59964dd0 sp 0x7ffd59964dc0
> WRITE of size 8 at 0x603000000028 thread T0
>   #0 0x562e1cc10789 in build_argv src/env.c:511
>   #1 0x562e1cc10982 in parse_split_string src/env.c:548
>   #2 0x562e1cc127bc in main src/env.c:849
>   #3 0x7f1c167e3b24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
>   #4 0x562e1cc0e54d in _start (coreutils-8.32/src/env+0x654d)
> 
> 0x603000000028 is located 0 bytes to the right of 24-byte region
> [0x603000000010,0x603000000028)
> allocated by thread T0 here:
>   #0 0x7f1c16a3b459 in __interceptor_malloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:145
>   #1 0x562e1cc19463 in xmalloc lib/xmalloc.c:41
>   #2 0x562e1cc0ff54 in build_argv src/env.c:404
>   #3 0x562e1cc10982 in parse_split_string src/env.c:548
>   #4 0x562e1cc127bc in main src/env.c:849
>   #5 0x7f1c167e3b24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)

Confirmed on an ASAN build of the latest source.
I'll fix it up.

thanks!
Pádraig

Message #11 received at 47412 <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Pádraig Brady <P <at> draigBrady.com>,
 Frank Busse <f.busse <at> imperial.ac.uk>, 47412 <at> debbugs.gnu.org
Subject: Re: bug#47412: env: fragile argument parsing
Date: Fri, 26 Mar 2021 13:49:24 -0700

On 3/26/21 1:12 PM, Pádraig Brady wrote:

> I'll fix it up.

I've got a fix. My goodness, that part of the code is messy.

Message #16 received at 47412-done <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Frank Busse <f.busse <at> imperial.ac.uk>
Cc: 47412-done <at> debbugs.gnu.org
Subject: Re: bug#47412: env: fragile argument parsing
Date: Fri, 26 Mar 2021 13:52:40 -0700

[Message part 1 (text/plain, inline)]

Thanks for the bug report. I installed the attached to fix it and am 
closing the report.

[0001-env-fix-address-violation-with-v-in-S.patch (text/x-patch, attachment)]

Message #19 received at 47412 <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Frank Busse <f.busse <at> imperial.ac.uk>
Cc: 47412 <at> debbugs.gnu.org
Subject: Re: bug#47412: env: fragile argument parsing
Date: Fri, 26 Mar 2021 15:21:01 -0700

[Message part 1 (text/plain, inline)]

I also installed the attached two followup patches to document this and 
issue a better warning in rare cases.

The -S code could use some more fixes in this area too - it can probably 
still dump core on platforms like the Hurd that don't limit exec arg 
size - but one thing at a time.

[0001-doc-document-env-fix.patch (text/x-patch, attachment)]

[0001-env-improve-whitespace-warning.patch (text/x-patch, attachment)]

Message #22 received at 47412 <at> debbugs.gnu.org (full text, mbox):

From: Pádraig Brady <P <at> draigBrady.com>
To: 47412 <at> debbugs.gnu.org, eggert <at> cs.ucla.edu, f.busse <at> imperial.ac.uk
Subject: Re: bug#47412: env: fragile argument parsing
Date: Mon, 29 Mar 2021 16:00:38 +0100

On 26/03/2021 20:52, Paul Eggert wrote:
> Thanks for the bug report. I installed the attached to fix it and am
> closing the report.

The fix looks good, thanks.
I added in a test case also at:
https://git.sv.gnu.org/gitweb/?p=coreutils.git;a=commitdiff;h=9f1bda18f

cheers,
Pádraig

Message #25 received at 47412 <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Frank Busse <f.busse <at> imperial.ac.uk>
Cc: 47412 <at> debbugs.gnu.org
Subject: Re: bug#47412: env: fragile argument parsing
Date: Mon, 29 Mar 2021 22:06:15 -0700

[Message part 1 (text/plain, inline)]

On 3/26/21 3:21 PM, Paul Eggert wrote:
> The -S code could use some more fixes in this area too - it can 
> probably still dump core on platforms like the Hurd that don't limit 
> exec arg size - but one thing at a time. 

I fixed the (unlikely) bugs I found in this area by installing the attached.

[0001-env-simplify-split-string-memory-management.patch (text/x-patch, attachment)]

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