On Sun, Apr 1, 2018 at 3:03 AM, Nikolay Borisov <nborisov@xxxxxxxx> wrote:
>
>
> 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.
OK, git describe e02119d5a7b4 doesn't show a tag though.
thanks,
liubo
>
>> ---
>> 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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