Messages in this thread Patch in this message | | | Date | Thu, 14 Jun 2012 16:56:27 -0700 | From | Greg KH <> | Subject | [ 04/42] btree: fix tree corruption in btree_get_prev() |
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3.4-stable review patch. If anyone has any objections, please let me know.
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From: Roland Dreier <roland@purestorage.com>
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.
[akpm@linux-foundation.org: avoid the double longcpy()] Signed-off-by: Roland Dreier <roland@purestorage.com> Acked-by: Joern Engel <joern@logfs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- 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; }
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