From ebfddb3d447f5267c76680ea4d242e6f9bcafa87 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Wed, 13 Sep 2017 16:28:23 -0700 Subject: [PATCH] fscache: fix fscache_objlist_show format processing gcc points out a minor bug in the handling of unknown cookie types, which could result in a string overflow when the integer is copied into a 3-byte string: fs/fscache/object-list.c: In function 'fscache_objlist_show': fs/fscache/object-list.c:265:19: error: 'sprintf' may write a terminating nul past the end of the destination [-Werror=format-overflow=] sprintf(_type, "%02u", cookie->def->type); ^~~~~~ fs/fscache/object-list.c:265:4: note: 'sprintf' output between 3 and 4 bytes into a destination of size 3 This is currently harmless as no code sets a type other than 0 or 1, but it makes sense to use snprintf() here to avoid overflowing the array if that changes. Link: http://lkml.kernel.org/r/20170714120720.906842-22-arnd@arndb.de Signed-off-by: Arnd Bergmann Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/fscache/object-list.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/fscache/object-list.c b/fs/fscache/object-list.c index 67f940892ef8..b5ab06fabc60 100644 --- a/fs/fscache/object-list.c +++ b/fs/fscache/object-list.c @@ -262,7 +262,8 @@ static int fscache_objlist_show(struct seq_file *m, void *v) type = "DT"; break; default: - sprintf(_type, "%02u", cookie->def->type); + snprintf(_type, sizeof(_type), "%02u", + cookie->def->type); type = _type; break; }