decompressors: check input size in decompress_inflate.c

Check for end of the input buffer when skipping over the filename field in
the .gz file header.

Signed-off-by: Lasse Collin <lasse.collin@tukaani.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Alain Knaff <alain@knaff.lu>
Cc: Albin Tonnerre <albin.tonnerre@free-electrons.com>
Cc: Phillip Lougher <phillip@lougher.demon.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 13 insertions, 4 deletions

diff --git a/lib/decompress_inflate.c b/lib/decompress_inflate.c
index b5fe1d1d5f05..19ff89e34eec 100644
--- a/lib/decompress_inflate.c
+++ b/lib/decompress_inflate.c
@@ -98,13 +98,22 @@ STATIC int INIT gunzip(unsigned char *buf, int len,
          * possible asciz filename)
          */
         strm->next_in = zbuf + 10;
+        strm->avail_in = len - 10;
         /* skip over asciz filename */
         if (zbuf[3] & 0x8) {
-                while (strm->next_in[0])
-                        strm->next_in++;
-                strm->next_in++;
+                do {
+                        /*
+                         * If the filename doesn't fit into the buffer,
+                         * the file is very probably corrupt. Don't try
+                         * to read more data.
+                         */
+                        if (strm->avail_in == 0) {
+                                error("header error");
+                                goto gunzip_5;
+                        }
+                        --strm->avail_in;
+                } while (*strm->next_in++);
         }
-        strm->avail_in = len - (strm->next_in - zbuf);
 
         strm->next_out = out_buf;
         strm->avail_out = out_len;