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patch 9.1.1683: xxd: Avoid null dereference in autoskip colorless

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Problem:  xxd: Avoid null dereference in autoskip colorless
Solution: Verify that colors is not null (Joakim Nohlgård)

Fixes bug introduced in 6897f18ee6
(v9.1.1459) which does a memcpy from NULL when color=never and the
autoskip option is used.

Before:

dd if=/dev/zero bs=100 count=1 status=none | xxd -a -R never
00000000: 0000 0000 0000 0000 0000 0000 0000 0000  ................
Segmentation fault (core dumped)

After:

dd if=/dev/zero bs=100 count=1 status=none | ./xxd/xxd -a -R never
00000000: 0000 0000 0000 0000 0000 0000 0000 0000  ................
*
00000060: 0000 0000                                ....

closes: #18008

Signed-off-by: Joakim Nohlgård <joakim@nohlgard.se>
Signed-off-by: Christian Brabandt <cb@256bit.org>
This commit is contained in:
Joakim Nohlgård
2025-08-24 12:36:44 +02:00
committed by Christian Brabandt
parent 99964e2ea7
commit b922b30cfe
3 changed files with 32 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
src/testdir/test_xxd.vim
View File

@ -701,4 +701,28 @@ func Test_xxd_overflow()
call assert_equal(expected, getline(1, 5))
bw!
endfunc
" this caused a NULL derefence
func Test_xxd_null_dereference()
CheckUnix
CheckExecutable /bin/true
new
" we are only checking, that there are addresses in the first 5 lines
let expected = [
\ '00000000: ',
\ '00000010: ',
\ '00000020: ',
\ '00000030: ',
\ '00000040: ']
exe "0r! " s:xxd_cmd "-a -R never /bin/true 2>&1"
" there should be more than 6 lines
call assert_true(line('$') > 5)
" there should not be an ASAN error message
call getline(1, '$')->join('\n')->assert_notmatch('runtime error')
6,$d
%s/^\x\+: \zs.*//g
call assert_equal(expected, getline(1, 5))
bw!
endfunc
" vim: shiftwidth=2 sts=2 expandtab

2
src/version.c
View File

@ -724,6 +724,8 @@ static char *(features[]) =
static int included_patches[] =
{ /* Add new patch number below this line */
/**/
1683,
/**/
1682,
/**/

8
src/xxd/xxd.c
View File

@ -70,6 +70,7 @@
* 15.06.2025 improve color code logic
* 08.08.2025 fix overflow with bitwise output
* 20.08.2025 remove external library call for autoconversion on z/OS (MVS)
* 24.08.2025 avoid NULL dereference with autoskip colorless
*
* (c) 1990-1998 by Juergen Weigert (jnweiger@gmail.com)
*
@ -150,7 +151,7 @@ extern void perror __P((char *));
# endif
#endif
char version[] = "xxd 2025-08-20 by Juergen Weigert et al.";
char version[] = "xxd 2025-08-24 by Juergen Weigert et al.";
#ifdef WIN32
char osver[] = " (Win32)";
#else
@ -599,7 +600,10 @@ xxdline(FILE *fp, char *l, char *colors, int nz)
if (!nz && zero_seen == 1)
{
strcpy(z, l);
memcpy(z_colors, colors, strlen(z));
if (colors)
{
memcpy(z_colors, colors, strlen(z));
}
}
if (nz || !zero_seen++)