[PATCH 11/20] ublk: move offset check out of __ublk_check_and_get_req()

Caleb Sander Mateos
2025-12-17T05:35:14Z

__ublk_check_and_get_req() checks that the passed in offset is within
the data length of the specified ublk request. However, only user copy
(ublk_check_and_get_req()) supports accessing ublk request data at a
nonzero offset. Zero-copy buffer registration (ublk_register_io_buf())
always passes 0 for the offset, so the check is unnecessary. Move the
check from __ublk_check_and_get_req() to ublk_check_and_get_req().

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
---
drivers/block/ublk_drv.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 273d580ddc46..7fa0a9f0bfae 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -252,11 +252,11 @@ struct ublk_params_header {

static void ublk_io_release(void *priv);
static void ublk_stop_dev_unlocked(struct ublk_device *ub);
static void ublk_abort_queue(struct ublk_device *ub, struct ublk_queue *ubq);
static inline struct request *__ublk_check_and_get_req(struct ublk_device *ub,
- u16 q_id, u16 tag, struct ublk_io *io, size_t offset);
+ u16 q_id, u16 tag, struct ublk_io *io);
static inline unsigned int ublk_req_build_flags(struct request *req);

static inline struct ublksrv_io_desc *
ublk_get_iod(const struct ublk_queue *ubq, unsigned tag)
{
@@ -2245,11 +2245,11 @@ static int ublk_register_io_buf(struct io_uring_cmd *cmd,
int ret;

if (!ublk_dev_support_zero_copy(ub))
return -EINVAL;

- req = __ublk_check_and_get_req(ub, q_id, tag, io, 0);
+ req = __ublk_check_and_get_req(ub, q_id, tag, io);
if (!req)
return -EINVAL;

ret = io_buffer_register_bvec(cmd, req, ublk_io_release, index,
issue_flags);
@@ -2539,11 +2539,11 @@ static int ublk_ch_uring_cmd_local(struct io_uring_cmd *cmd,
__func__, cmd_op, tag, ret, io ? io->flags : 0);
return ret;
}

static inline struct request *__ublk_check_and_get_req(struct ublk_device *ub,
- u16 q_id, u16 tag, struct ublk_io *io, size_t offset)
+ u16 q_id, u16 tag, struct ublk_io *io)
{
struct request *req;

/*
* can't use io->req in case of concurrent UBLK_IO_COMMIT_AND_FETCH_REQ,
@@ -2560,13 +2560,10 @@ static inline struct request *__ublk_check_and_get_req(struct ublk_device *ub,
goto fail_put;

if (!ublk_rq_has_data(req))
goto fail_put;

- if (offset > blk_rq_bytes(req))
- goto fail_put;
-
return req;
fail_put:
ublk_put_req_ref(io, req);
return NULL;
}
@@ -2644,14 +2641,19 @@ ublk_user_copy(struct kiocb *iocb, struct iov_iter *iter, int dir)

if (tag >= ub->dev_info.queue_depth)
return -EINVAL;

io = &ubq->ios[tag];
- req = __ublk_check_and_get_req(ub, q_id, tag, io, buf_off);
+ req = __ublk_check_and_get_req(ub, q_id, tag, io);
if (!req)
return -EINVAL;

+ if (buf_off > blk_rq_bytes(req)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
if (!ublk_check_ubuf_dir(req, dir)) {
ret = -EACCES;
goto out;
}

--
2.45.2