diff options
| author | Shaohua Li <shli@fb.com> | 2017-09-01 21:15:17 +0300 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2017-09-01 22:57:33 +0300 |
| commit | 92d773324b7edbd36bf0c28c1e0157763aeccc92 (patch) | |
| tree | 333db14ef4338ba1daa5063535730c9c3ea3b0d9 /drivers/block/loop.c | |
| parent | 12cd3a2fe3ba6d1a2cf007e4e8dcfbe66d3d0a28 (diff) | |
| download | linux-92d773324b7edbd36bf0c28c1e0157763aeccc92.tar.xz | |
block/loop: fix use after free
lo_rw_aio->call_read_iter->
1 aops->direct_IO
2 iov_iter_revert
lo_rw_aio_complete could happen between 1 and 2, the bio and bvec could
be freed before 2, which accesses bvec.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/block/loop.c')
| -rw-r--r-- | drivers/block/loop.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 3a35121f8a6f..78c47c4b584d 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -463,14 +463,21 @@ static void lo_complete_rq(struct request *rq) blk_mq_end_request(rq, cmd->ret < 0 ? BLK_STS_IOERR : BLK_STS_OK); } +static void lo_rw_aio_do_completion(struct loop_cmd *cmd) +{ + if (!atomic_dec_and_test(&cmd->ref)) + return; + kfree(cmd->bvec); + cmd->bvec = NULL; + blk_mq_complete_request(cmd->rq); +} + static void lo_rw_aio_complete(struct kiocb *iocb, long ret, long ret2) { struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb); - kfree(cmd->bvec); - cmd->bvec = NULL; cmd->ret = ret; - blk_mq_complete_request(cmd->rq); + lo_rw_aio_do_completion(cmd); } static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, @@ -518,6 +525,7 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); segments = bio_segments(bio); } + atomic_set(&cmd->ref, 2); iov_iter_bvec(&iter, ITER_BVEC | rw, bvec, segments, blk_rq_bytes(rq)); @@ -533,6 +541,8 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, else ret = call_read_iter(file, &cmd->iocb, &iter); + lo_rw_aio_do_completion(cmd); + if (ret != -EIOCBQUEUED) cmd->iocb.ki_complete(&cmd->iocb, ret, 0); return 0; |