From: Shaohua Li <shli@xxxxxx>
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@xxxxxx>
---
drivers/block/loop.c | 16 +++++++++++++---
drivers/block/loop.h | 5 ++++-
2 files changed, 17 insertions(+), 4 deletions(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 3a35121..78c47c4 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;
diff --git a/drivers/block/loop.h b/drivers/block/loop.h
index 43d20d3..b0ba4a5 100644
--- a/drivers/block/loop.h
+++ b/drivers/block/loop.h
@@ -68,7 +68,10 @@ struct loop_cmd {
struct kthread_work work;
struct request *rq;
struct list_head list;
- bool use_aio; /* use AIO interface to handle I/O */
+ union {
+ bool use_aio; /* use AIO interface to handle I/O */
+ atomic_t ref; /* only for aio */
+ };
long ret;
struct kiocb iocb;
struct bio_vec *bvec;
--
2.9.5
