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| author | Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> | 2014-05-17 20:56:38 +0900 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-11-14 08:59:46 -0800 |
| commit | 3fd35793ac58c8d2f578f62a867b274d50490791 (patch) | |
| tree | 7f619d9687f57b88c0eb608a608352861bd3dc00 /fs | |
| parent | 9c5f9dcad8be822dd4ebe7f9640b0c8af2c57122 (diff) | |
| download | lwn-3fd35793ac58c8d2f578f62a867b274d50490791.tar.gz lwn-3fd35793ac58c8d2f578f62a867b274d50490791.zip | |
fs: Fix theoretical division by 0 in super_cache_scan().
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>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/super.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/fs/super.c b/fs/super.c index 7624267b2043..88a6bc6e3cc9 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); |