From 475d0db742e3755c6b267f48577ff7cbb7dfda0d Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Sat, 17 May 2014 20:56:38 +0900 Subject: fs: Fix theoretical division by 0 in super_cache_scan(). 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 Cc: stable # 3.1+ Signed-off-by: Al Viro --- fs/super.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'fs/super.c') diff --git a/fs/super.c b/fs/super.c index b9a214d2fe98..6f8c954315c0 100644 --- a/fs/super.c +++ b/fs/super.c @@ -80,6 +80,8 @@ static unsigned long super_cache_scan(struct shrinker *shrink, inodes = list_lru_count_node(&sb->s_inode_lru, sc->nid); dentries = list_lru_count_node(&sb->s_dentry_lru, sc->nid); total_objects = dentries + inodes + fs_objects + 1; + if (!total_objects) + total_objects = 1; /* proportion the scan between the caches */ dentries = mult_frac(sc->nr_to_scan, dentries, total_objects); -- cgit v1.2.3-59-g8ed1b