Commit f4cfb18d authored Oct 15, 2008 by Volodymyr G. Lukiianyk Committed by Linus Torvalds Oct 16, 2008

uclinux: fix gzip header parsing in binfmt_flat.c

There are off-by-one errors in decompress_exec() when calculating the length of
optional "original file name" and "comment" fields: the "ret" index is not
incremented when terminating '\0' character is reached. The check of the buffer
overflow (after an "extra-field" length was taken into account) is also fixed.

I've encountered this off-by-one error when tried to reuse
gzip-header-parsing part of the decompress_exec() function. There was an
"original file name" field in the payload (with miscalculated length) and
zlib_inflate() returned Z_DATA_ERROR. But after the fix similar to this
one all worked fine.

Signed-off-by: Volodymyr G Lukiianyk <volodymyrgl@gmail.com>
Acked-by: Greg Ungerer <gerg@snapgear.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 0c6aa263

fs/binfmt_flat.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -229,13 +229,13 @@ static int decompress_exec(
		ret = 10;
		if (buf[3] & EXTRA_FIELD) {
		ret += 2 + buf[10] + (buf[11] << 8);
		if (unlikely(LBUFSIZE == ret)) {
		if (unlikely(LBUFSIZE <= ret)) {
		DBG_FLT("binfmt_flat: buffer overflow (EXTRA)?\n");
		goto out_free_buf;
		}
		}
		if (buf[3] & ORIG_NAME) {
		for (; ret < LBUFSIZE && (buf[ret] != 0); ret++)
		while (ret < LBUFSIZE && buf[ret++] != 0)
		;
		if (unlikely(LBUFSIZE == ret)) {
		DBG_FLT("binfmt_flat: buffer overflow (ORIG_NAME)?\n");
		@@ -243,7 +243,7 @@ static int decompress_exec(
		}
		}
		if (buf[3] & COMMENT) {
		for (; ret < LBUFSIZE && (buf[ret] != 0); ret++)
		while (ret < LBUFSIZE && buf[ret++] != 0)
		;
		if (unlikely(LBUFSIZE == ret)) {
		DBG_FLT("binfmt_flat: buffer overflow (COMMENT)?\n");