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Commit cbf8ae32 authored by Roland Dreier's avatar Roland Dreier Committed by Linus Torvalds
Browse files

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: default avatarRoland Dreier <roland@purestorage.com>
Acked-by: default avatarJoern Engel <joern@logfs.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7d8a4569

lib/btree.c

+2 −2
Original line number Diff line number Diff line
@@ -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 @@ void *btree_get_prev(struct btree_head *head, struct btree_geo *geo, 
	}

miss:

	if (retry_key) {

		__key = retry_key;

		longcpy(key, retry_key, geo->keylen);

		retry_key = NULL;

		goto retry;

	}