| From | Kamal Mostafa <> | Subject | [PATCH 3.13 084/105] fs: Fix theoretical division by 0 in super_cache_scan(). | Date | Mon, 27 Oct 2014 11:56:59 -0700 |
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3.13.11.10 -stable review patch. If anyone has any objections, please let me know.
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From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
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 <penguin-kernel@I-love.SAKURA.ne.jp> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- fs/super.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/fs/super.c b/fs/super.c index e5f6c2c..97edaa93 100644 --- a/fs/super.c +++ b/fs/super.c @@ -81,6 +81,8 @@ 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); -- 1.9.1
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