This is a note to let you know that I've just added the patch titled

    btree: fix tree corruption in btree_get_prev()

to the 3.4-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:
     btree-fix-tree-corruption-in-btree_get_prev.patch
and it can be found in the queue-3.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.


>From cbf8ae32f66a9ceb8907ad9e16663c2a29e48990 Mon Sep 17 00:00:00 2001
From: Roland Dreier <[email protected]>
Date: Thu, 7 Jun 2012 14:21:13 -0700
Subject: btree: fix tree corruption in btree_get_prev()

From: Roland Dreier <[email protected]>

commit cbf8ae32f66a9ceb8907ad9e16663c2a29e48990 upstream.

The memory the parameter __key points to is used as an iterator in
btree_get_prev(), so if we save off a bkey() pointer in retry_key and
then assign that to __key, we'll end up corrupting the btree internals
when we do eg

        longcpy(__key, bkey(geo, node, i), geo->keylen);

to return the key value.  What we should do instead is use longcpy() to
copy the key value that retry_key points to __key.

This can cause a btree to get corrupted by seemingly read-only
operations such as btree_for_each_safe.

[[email protected]: avoid the double longcpy()]
Signed-off-by: Roland Dreier <[email protected]>
Acked-by: Joern Engel <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 lib/btree.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/lib/btree.c
+++ b/lib/btree.c
@@ -319,8 +319,8 @@ void *btree_get_prev(struct btree_head *
 
        if (head->height == 0)
                return NULL;
-retry:
        longcpy(key, __key, geo->keylen);
+retry:
        dec_key(geo, key);
 
        node = head->node;
@@ -351,7 +351,7 @@ retry:
        }
 miss:
        if (retry_key) {
-               __key = retry_key;
+               longcpy(key, retry_key, geo->keylen);
                retry_key = NULL;
                goto retry;
        }


Patches currently in stable-queue which might be from [email protected] are

queue-3.4/btree-fix-tree-corruption-in-btree_get_prev.patch
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