squashfs: Fix heap corruption in sqfs_search_dir()

res needs to be large enough to store both strings rem and target,
plus the path separator and the terminator.
Currently the space for the path separator is not accounted, so
the heap is corrupted by one byte.

Signed-off-by: Richard Weinberger <richard@nod.at>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>

diff --git a/fs/squashfs/sqfs.c b/fs/squashfs/sqfs.c
index af7ff80..b931401 100644 (file)
--- a/fs/squashfs/sqfs.c
+++ b/fs/squashfs/sqfs.c
@@ -567,8 +567,11 @@ static int sqfs_search_dir(struct squashfs_dir_stream *dirs, char **token_list,
                                ret = -ENOMEM;
                                goto out;
                        }
-                       /* Concatenate remaining tokens and symlink's target */
-                       res = malloc(strlen(rem) + strlen(target) + 1);
+                       /*
+                        * Concatenate remaining tokens and symlink's target.
+                        * Allocate enough space for rem, target, '/' and '\0'.
+                        */
+                       res = malloc(strlen(rem) + strlen(target) + 2);
                        if (!res) {
                                ret = -ENOMEM;
                                goto out;