From: Tetsuo Handa Date: Sat, 17 May 2014 11:56:38 +0000 (+0900) Subject: fs: Fix theoretical division by 0 in super_cache_scan(). X-Git-Tag: firefly_0821_release~3679^2~1316 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=d016a08a18158fd7002ad24aea8a0224ce2a3d0c;p=firefly-linux-kernel-4.4.55.git fs: Fix theoretical division by 0 in super_cache_scan(). commit 475d0db742e3755c6b267f48577ff7cbb7dfda0d upstream. total_objects could be 0 and is used as a denom. While total_objects is a "long", total_objects == 0 unlikely happens for 3.12 and later kernels because 32-bit architectures would not be able to hold (1 << 32) objects. However, total_objects == 0 may happen for kernels between 3.1 and 3.11 because total_objects in prune_super() was an "int" and (e.g.) x86_64 architecture might be able to hold (1 << 32) objects. Signed-off-by: Tetsuo Handa Reviewed-by: Christoph Hellwig Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/super.c b/fs/super.c index 68307c029228..e028b508db25 100644 --- a/fs/super.c +++ b/fs/super.c @@ -76,6 +76,8 @@ static int prune_super(struct shrinker *shrink, struct shrink_control *sc) total_objects = sb->s_nr_dentry_unused + sb->s_nr_inodes_unused + fs_objects + 1; + if (!total_objects) + total_objects = 1; if (sc->nr_to_scan) { int dentries;