patch 9.1.0094: xxd: buffer-overflow when writing color output

Problem:  xxd: buffer-overflow when writing color output
Solution: properly account for the color escape sequences and
          adjust LLEN macro
          (Goffredo Baroncelli)

xxd: crash with higer number of column

xxd writes the data into a buffer before printing. Unfortunately
the buffer doesn't consider the space consumed by the escape
sequences used to change the color of the character.

BEFORE:
$ xxd -Ralways -c 256 /etc/passwd
Segmentation fault (core dumped)

AFTER:
$ ./xxd -Ralways -c 256 /etc/passwd
00000000: 726f 6f74 3a78 3a30 3a30 3a72 6f6f 743a 2f72 [...]

To solve this issue I had to increase the size of the buffer
considering for each byte of data 11 further characters for the
color escape sequence.

closes: #14003

Signed-off-by: Goffredo Baroncelli <kreijack@libero.it>
Signed-off-by: Christian Brabandt <cb@256bit.org>

diff --git a/src/version.c b/src/version.c
index 685f8b0df3b6e198dcd422abfadcfc66b56c559a..598a957ad5f28ded9a6a854209944c3740377003 100644 (file)
--- a/src/version.c
+++ b/src/version.c
@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    94,
 /**/
     93,
 /**/

diff --git a/src/xxd/xxd.c b/src/xxd/xxd.c
index a5f5f04ade27d1dbd93cf9c021cdee4a477caf20..cf8b4ea6a0e2acde115d35aff178d7f9f45bdfec 100644 (file)
--- a/src/xxd/xxd.c
+++ b/src/xxd/xxd.c
@@ -61,6 +61,7 @@
  * 12.01.2024  disable auto-conversion for z/OS (MVS)
  * 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
  *
  * (c) 1990-1998 by Juergen Weigert (jnweiger@gmail.com)
  *
@@ -141,7 +142,7 @@ extern void perror __P((char *));
 # endif
 #endif
 
-char version[] = "xxd 2024-01-25 by Juergen Weigert et al.";
+char version[] = "xxd 2024-02-10 by Juergen Weigert et al.";
 #ifdef WIN32
 char osver[] = " (Win32)";
 #else
@@ -200,7 +201,33 @@ char osver[] = "";
 
 #define TRY_SEEK       /* attempt to use lseek, or skip forward by reading */
 #define COLS 256       /* change here, if you ever need more columns */
-#define LLEN ((2*(int)sizeof(unsigned long)) + 4 + (9*COLS-1) + COLS + 2)
+
+/*
+ * 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
+ */
+#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 */
 
 char hexxa[] = "0123456789abcdef0123456789ABCDEF", *hexx = hexxa;