patch 9.1.0404: [security] xxd: buffer-overflow with specific flags
Problem: [security] xxd: buffer-overflow with specific flags
Solution: Correctly calculate the required buffer space
(Lennard Hofmann)
xxd writes each output line into a global buffer before printing.
The maximum size of that buffer was not calculated correctly.
This command was crashing in AddressSanitizer:
$ xxd -Ralways -g1 -c256 -d -o 9223372036854775808 /etc/passwd
This prints a line of 6680 bytes but the buffer only had room for 6549 bytes.
If the output from "-b" was colored, the line could be even longer.
closes: #14738
Co-authored-by: K.Takata <kentkt@csc.jp>
Signed-off-by: Lennard Hofmann <lennard.hofmann@web.de>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_xxd.vim b/src/testdir/test_xxd.vim
index 7a2771e..642f5e7 100644
--- a/src/testdir/test_xxd.vim
+++ b/src/testdir/test_xxd.vim
@@ -411,6 +411,19 @@
endfor
endfunc
+
+" Try to trigger a buffer overflow (#14738)
+func Test_xxd_buffer_overflow()
+ CheckUnix
+ new
+ let input = repeat('A', 256)
+ call writefile(['-9223372036854775808: ' . repeat("\e[1;32m41\e[0m ", 256) . ' ' . repeat("\e[1;32mA\e[0m", 256)], 'Xxdexpected', 'D')
+ exe 'r! printf ' . input . '| ' . s:xxd_cmd . ' -Ralways -g1 -c256 -d -o 9223372036854775808 > Xxdout'
+ call assert_equalfile('Xxdexpected', 'Xxdout')
+ call delete('Xxdout')
+ bwipe!
+endfunc
+
" -c0 selects the format specific default column value, as if no -c was given
" except for -ps, where it disables extra newlines
func Test_xxd_c0_is_def_cols()
diff --git a/src/version.c b/src/version.c
index 954b747..6bb8be6 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
static int included_patches[] =
{ /* Add new patch number below this line */
/**/
+ 404,
+/**/
403,
/**/
402,
diff --git a/src/xxd/xxd.c b/src/xxd/xxd.c
index cf8b4ea..7a3d36a 100644
--- a/src/xxd/xxd.c
+++ b/src/xxd/xxd.c
@@ -62,6 +62,7 @@
* 17.01.2024 use size_t instead of usigned int for code-generation (-i), #13876
* 25.01.2024 revert the previous patch (size_t instead of unsigned int)
* 10.02.2024 fix buffer-overflow when writing color output to buffer, #14003
+ * 10.05.2024 fix another buffer-overflow when writing colored output to buffer, #14738
*
* (c) 1990-1998 by Juergen Weigert (jnweiger@gmail.com)
*
@@ -142,7 +143,7 @@
# endif
#endif
-char version[] = "xxd 2024-02-10 by Juergen Weigert et al.";
+char version[] = "xxd 2024-05-10 by Juergen Weigert et al.";
#ifdef WIN32
char osver[] = " (Win32)";
#else
@@ -205,29 +206,16 @@
/*
* LLEN is the maximum length of a line; other than the visible characters
* we need to consider also the escape color sequence prologue/epilogue ,
- * (11 bytes for each character). The most larger format is the default one:
- * addr + 1 word for each col/2 + 1 char for each col
- *
- * addr 1st group 2nd group
- * +-------+ +-----------------+ +------+
- * 01234567: 1234 5678 9abc def0 12345678
- *
- * - addr: typically 012345678: -> from 10 up to 18 bytes (including trailing
- * space)
- * - 1st group: 1234 5678 9abc ... -> each byte may be colored, so add 11
- * for each byte
- * - space -> 1 byte
- * - 2nd group: 12345678 -> each char may be colore so add 11
- * for each byte
- * - new line -> 1 byte
- * - zero (end line) -> 1 byte
+ * (11 bytes for each character).
*/
-#define LLEN (2*(int)sizeof(unsigned long) + 2 + /* addr + ": " */ \
- (11 * 2 + 4 + 1) * (COLS / 2) + /* 1st group */ \
- 1 + /* space */ \
- (1 + 11) * COLS + /* 2nd group */ \
- 1 + /* new line */ \
- 1) /* zero */
+#define LLEN \
+ (39 /* addr: ⌈log10(ULONG_MAX)⌉ if "-d" flag given. We assume ULONG_MAX = 2**128 */ \
+ + 2 /* ": " */ \
+ + 13 * COLS /* hex dump with colors */ \
+ + (COLS - 1) /* whitespace between groups if "-g1" option given and "-c" maxed out */ \
+ + 2 /* whitespace */ \
+ + 12 * COLS /* ASCII dump with colors */ \
+ + 2) /* "\n\0" */
char hexxa[] = "0123456789abcdef0123456789ABCDEF", *hexx = hexxa;