On 31.03.2018 01:11, Liu Bo wrote:
> 0, 1 and <0 can be returned by btrfs_next_leaf(), and when <0 is
> returned, path->nodes[0] could be NULL, log_dir_items lacks such a
> check for <0 and we may run into a null pointer dereference panic.
>
> Signed-off-by: Liu Bo <bo.liu@xxxxxxxxxxxxxxxxx>
Reviewed-by: Nikolay Borisov <nborisov@xxxxxxxx>
This bug has been present ever since 2.6.29 (e02119d5a7b4 ("Btrfs: Add a
write ahead tree log to optimize synchronous operations"))
so this needs a stable tag.
> ---
> fs/btrfs/tree-log.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
> index 4344577..4ee9431 100644
> --- a/fs/btrfs/tree-log.c
> +++ b/fs/btrfs/tree-log.c
> @@ -3518,8 +3518,11 @@ static noinline int log_dir_items(struct btrfs_trans_handle *trans,
> * from this directory and from this transaction
> */
> ret = btrfs_next_leaf(root, path);
> - if (ret == 1) {
> - last_offset = (u64)-1;
> + if (ret) {
> + if (ret == 1)
> + last_offset = (u64)-1;
> + else
> + err = ret;
> goto done;
> }
> btrfs_item_key_to_cpu(path->nodes[0], &tmp, path->slots[0]);
>
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