This is a note to let you know that I've just added the patch titled
fs: Fix theoretical division by 0 in super_cache_scan().
to the 3.17-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
fs-fix-theoretical-division-by-0-in-super_cache_scan.patch
and it can be found in the queue-3.17 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 475d0db742e3755c6b267f48577ff7cbb7dfda0d Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Date: Sat, 17 May 2014 20:56:38 +0900
Subject: fs: Fix theoretical division by 0 in super_cache_scan().
From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/super.c | 2 ++
1 file changed, 2 insertions(+)
--- a/fs/super.c
+++ b/fs/super.c
@@ -80,6 +80,8 @@ static unsigned long super_cache_scan(st
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);
Patches currently in stable-queue which might be from penguin-kernel@xxxxxxxxxxxxxxxxxxx are
queue-3.17/fs-fix-theoretical-division-by-0-in-super_cache_scan.patch
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