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fs: Fix theoretical division by 0 in super_cache_scan().

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commit 475d0db742 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tetsuo Handa
2014-05-17 20:56:38 +09:00
committed by Greg Kroah-Hartman
parent f83813a8af
commit d016a08a18
1 changed files with 2 additions and 0 deletions
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2
fs/super.c
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@@ -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;