On 6/12/19 11:57 AM, Vlastimil Babka wrote:
> On 7/17/18 6:00 PM, Andrey Ryabinin wrote:
>> fuse_dev_splice_write() reads pipe->buffers to determine the size of
>> 'bufs' array before taking the pipe_lock(). This is not safe as
>> another thread might change the 'pipe->buffers' between the allocation
>> and taking the pipe_lock(). So we end up with too small 'bufs' array.
>>
>> Move the bufs allocations inside pipe_lock()/pipe_unlock() to fix this.
>>
>> Fixes: dd3bb14f44a6 ("fuse: support splice() writing to fuse device")
>> Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com>
>> Cc: <sta...@vger.kernel.org>
>
> BTW, why don't we need to do the same in fuse_dev_splice_read()?
>
do_splice() already takes the pipe_lock() before calling ->splice_read()
> Thanks,
> Vlastimil
>
>> ---
>> fs/fuse/dev.c | 7 +++++--
>> 1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
>> index c6b88fa85e2e..702592cce546 100644
>> --- a/fs/fuse/dev.c
>> +++ b/fs/fuse/dev.c
>> @@ -1944,12 +1944,15 @@ static ssize_t fuse_dev_splice_write(struct
>> pipe_inode_info *pipe,
>> if (!fud)
>> return -EPERM;
>>
>> + pipe_lock(pipe);
>> +
>> bufs = kmalloc_array(pipe->buffers, sizeof(struct pipe_buffer),
>> GFP_KERNEL);
>> - if (!bufs)
>> + if (!bufs) {
>> + pipe_unlock(pipe);
>> return -ENOMEM;
>> + }
>>
>> - pipe_lock(pipe);
>> nbuf = 0;
>> rem = 0;
>> for (idx = 0; idx < pipe->nrbufs && rem < len; idx++)
>>
>
