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From: Nikolay Borisov <nborisov@suse.com>
To: linux-btrfs@vger.kernel.org
Cc: Nikolay Borisov <nborisov@suse.com>
Subject: [PATCH] btrfs-progs: Fix null pointer deref in balance_level
Date: Tue,  6 Apr 2021 16:55:03 +0300	[thread overview]
Message-ID: <20210406135503.164590-1-nborisov@suse.com> (raw)

In case the right buffer is emptied it's first set to null and
subsequently it's dereferenced to get its size to pass to root_sub_used.
This naturally leads to a null pointer dereference. The correct thing
to do is to pass the stashed right->len in "blocksize".

Fixes #296

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
---
 kernel-shared/ctree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel-shared/ctree.c b/kernel-shared/ctree.c
index 4cc3aebc1412..3a82286cc914 100644
--- a/kernel-shared/ctree.c
+++ b/kernel-shared/ctree.c
@@ -927,7 +927,7 @@ static int balance_level(struct btrfs_trans_handle *trans,
 			if (wret)
 				ret = wret;
 
-			root_sub_used(root, right->len);
+			root_sub_used(root, blocksize);
 			wret = btrfs_free_extent(trans, root, bytenr,
 						 blocksize, 0,
 						 root->root_key.objectid,
-- 
2.25.1


             reply	other threads:[~2021-04-06 13:55 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-06 13:55 Nikolay Borisov [this message]
2021-04-08 18:17 ` [PATCH] btrfs-progs: Fix null pointer deref in balance_level Josef Bacik
2021-04-16 18:18 ` David Sterba

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