| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.10 012/123] fs: Fix theoretical division by 0 in super_cache_scan(). | Date | Wed, 12 Nov 2014 10:16:18 +0900 |
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3.10-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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- fs/super.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/fs/super.c +++ b/fs/super.c @@ -76,6 +76,8 @@ static int prune_super(struct shrinker * 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;
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