From cbf8ae32f66a9ceb8907ad9e16663c2a29e48990 Mon Sep 17 00:00:00 2001 From: Roland Dreier Date: Thu, 7 Jun 2012 14:21:13 -0700 Subject: [PATCH] btree: fix tree corruption in btree_get_prev() 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 Acked-by: Joern Engel Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/btree.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/lib/btree.c b/lib/btree.c index e5ec1e9c1aa5..5cf9e74ec3f3 100644 --- a/lib/btree.c +++ b/lib/btree.c @@ -319,8 +319,8 @@ void *btree_get_prev(struct btree_head *head, struct btree_geo *geo, 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; } -- 2.20.1