lib/hexdump.c: truncate output in case of overflow

There is a classical off-by-one error in case when we try to place, for
example, 1+1 bytes as hex in the buffer of size 6.  The expected result is
to get an output truncated, but in the reality we get 6 bytes filed
followed by terminating NUL.

Change the logic how we fill the output in case of byte dumping into
limited space.  This will follow the snprintf() behaviour by truncating
output even on half bytes.

Fixes: 114fc1afb2de (hexdump: make it return number of bytes placed in buffer)
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reported-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Tested-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/lib/hexdump.c b/lib/hexdump.c
index 8d74c20d8595c76d3882fcc02a7fa00f8db1bfaa..992457b1284c186d8e0d7b8c5d7b5fc349c18ef3 100644 (file)
--- a/lib/hexdump.c
+++ b/lib/hexdump.c
@@ -169,11 +169,15 @@ int hex_dump_to_buffer(const void *buf, size_t len, int rowsize, int groupsize,
                }
        } else {
                for (j = 0; j < len; j++) {
-                       if (linebuflen < lx + 3)
+                       if (linebuflen < lx + 2)
                                goto overflow2;
                        ch = ptr[j];
                        linebuf[lx++] = hex_asc_hi(ch);
+                       if (linebuflen < lx + 2)
+                               goto overflow2;
                        linebuf[lx++] = hex_asc_lo(ch);
+                       if (linebuflen < lx + 2)
+                               goto overflow2;
                        linebuf[lx++] = ' ';
                }
                if (j)