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authorTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>2014-05-17 15:56:38 +0400
committerAl Viro <viro@zeniv.linux.org.uk>2014-10-09 10:39:02 +0400
commit475d0db742e3755c6b267f48577ff7cbb7dfda0d (patch)
tree68d3bf447201d86cc46ca0b8292d803c2a728b12 /fs/super.c
parentb8314f9303a985354f445763960c0db2d7948891 (diff)
downloadlinux-475d0db742e3755c6b267f48577ff7cbb7dfda0d.tar.xz
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 <penguin-kernel@I-love.SAKURA.ne.jp> Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: stable <stable@kernel.org> # 3.1+ Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/super.c')
-rw-r--r--fs/super.c2
1 files changed, 2 insertions, 0 deletions
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);