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authorArnd Bergmann <arnd@arndb.de>2017-09-13 16:28:23 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-09-13 18:53:15 -0700
commitebfddb3d447f5267c76680ea4d242e6f9bcafa87 (patch)
treee3b10c4586e31933b9e157328b7952ce1bd95175 /fs/fscache
parent8185f5708d2488393dc2acec21d19ac53d61b4a0 (diff)
downloadlinux-ebfddb3d447f5267c76680ea4d242e6f9bcafa87.tar.gz
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 <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/fscache')
-rw-r--r--fs/fscache/object-list.c3
1 files changed, 2 insertions, 1 deletions
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;
 		}