Thread (3 messages) 3 messages, 3 authors, 2017-09-06

Re: [PATCH] btrfs: fix NULL pointer dereference from free_reloc_roots()

From: Nikolay Borisov <hidden>
Date: 2017-08-25 05:49:14


On 25.08.2017 08:15, Naohiro Aota wrote:
__del_reloc_root should be called before freeing up reloc_root->node.
If not, calling __del_reloc_root() dereference reloc_root->node, causing
the system BUG.

Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
This patch should also have:

Fixes: 6bdf131fac23 ("Btrfs: don't leak reloc root nodes on error")
Cc: <redacted> # 4.9

With that:

Reviewed-by: Nikolay Borisov <redacted>
quoted hunk ↗ jump to hunk
---
 fs/btrfs/relocation.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 65661d1aae4e..6445de8e9ece 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -2393,11 +2393,11 @@ void free_reloc_roots(struct list_head *list)
 	while (!list_empty(list)) {
 		reloc_root = list_entry(list->next, struct btrfs_root,
 					root_list);
+		__del_reloc_root(reloc_root);
 		free_extent_buffer(reloc_root->node);
 		free_extent_buffer(reloc_root->commit_root);
 		reloc_root->node = NULL;
 		reloc_root->commit_root = NULL;
-		__del_reloc_root(reloc_root);
 	}
 }
 

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