On Sun, Apr 1, 2018 at 3:03 AM, Nikolay Borisov <nbori...@suse.com> 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....@linux.alibaba.com>
> Reviewed-by: Nikolay Borisov <nbori...@suse.com>
>
> 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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