* [PATCH v2] io_uring: Add size check for sqe->cmd
@ 2026-01-29 23:54 Govindarajulu Varadarajan
2026-01-30 1:27 ` Caleb Sander Mateos
0 siblings, 1 reply; 2+ messages in thread
From: Govindarajulu Varadarajan @ 2026-01-29 23:54 UTC (permalink / raw)
To: io-uring, axboe
Cc: ming.lei, kbusch, hch, sagi, miklos, Govindarajulu Varadarajan
For SQE128, sqe->cmd provides 80 bytes for uring_cmd. Add macro to
check if size of user struct does not exceed 80 bytes at compile time.
User doesn't have to track this manually during development.
Replace io_uring_sqe_cmd() inline func with macro and add
io_uring_sqe128_cmd() which checks struct
size for 16 bytes cmd and 80 bytes cmd respectively.
Signed-off-by: Govindarajulu Varadarajan <govind.varadar@gmail.com>
---
v2:
- Replace all caps macro with lower case definition.
- Add const qualifier to return type.
- Rebase on top of series "[PATCH 0/4] ublk: fix struct
ublksrv_ctrl_cmd accesses"
BRANCH: for-7.0/block
Depends-on series: "[PATCH 0/4] ublk: fix struct ublksrv_ctrl_cmd
accesses"
Needs "[PATCH 2/4] ublk: don't write to struct ublksrv_ctrl_cmd" to
avoid merge conflict.
---
drivers/block/ublk_drv.c | 14 +++++++++-----
drivers/nvme/host/ioctl.c | 3 ++-
fs/fuse/dev_uring.c | 6 ++++--
include/linux/io_uring/cmd.h | 15 +++++++++++----
4 files changed, 26 insertions(+), 12 deletions(-)
diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 0e25a59849ae..3f9d6dc3afef 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -3244,7 +3244,8 @@ static int ublk_ch_uring_cmd_local(struct io_uring_cmd *cmd,
unsigned int issue_flags)
{
/* May point to userspace-mapped memory */
- const struct ublksrv_io_cmd *ub_src = io_uring_sqe_cmd(cmd->sqe);
+ const struct ublksrv_io_cmd *ub_src = io_uring_sqe_cmd(cmd->sqe,
+ struct ublksrv_io_cmd);
u16 buf_idx = UBLK_INVALID_BUF_IDX;
struct ublk_device *ub = cmd->file->private_data;
struct ublk_queue *ubq;
@@ -3824,7 +3825,8 @@ static int ublk_validate_batch_fetch_cmd(struct ublk_batch_io_data *data)
static int ublk_handle_non_batch_cmd(struct io_uring_cmd *cmd,
unsigned int issue_flags)
{
- const struct ublksrv_io_cmd *ub_cmd = io_uring_sqe_cmd(cmd->sqe);
+ const struct ublksrv_io_cmd *ub_cmd = io_uring_sqe_cmd(cmd->sqe,
+ struct ublksrv_io_cmd);
struct ublk_device *ub = cmd->file->private_data;
unsigned tag = READ_ONCE(ub_cmd->tag);
unsigned q_id = READ_ONCE(ub_cmd->q_id);
@@ -3853,7 +3855,7 @@ static int ublk_handle_non_batch_cmd(struct io_uring_cmd *cmd,
static int ublk_ch_batch_io_uring_cmd(struct io_uring_cmd *cmd,
unsigned int issue_flags)
{
- const struct ublk_batch_io *uc = io_uring_sqe_cmd(cmd->sqe);
+ const struct ublk_batch_io *uc = io_uring_sqe_cmd(cmd->sqe, struct ublk_batch_io);
struct ublk_device *ub = cmd->file->private_data;
struct ublk_batch_io_data data = {
.ub = ub,
@@ -5106,7 +5108,8 @@ static int ublk_char_dev_permission(struct ublk_device *ub,
static int ublk_ctrl_uring_cmd_permission(struct ublk_device *ub,
struct io_uring_cmd *cmd, u64 *addr, u16 *len)
{
- const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
+ const struct ublksrv_ctrl_cmd *header = io_uring_sqe128_cmd(cmd->sqe,
+ struct ublksrv_ctrl_cmd);
bool unprivileged = ub->dev_info.flags & UBLK_F_UNPRIVILEGED_DEV;
void __user *argp = (void __user *)*addr;
char *dev_path = NULL;
@@ -5199,7 +5202,8 @@ static bool ublk_ctrl_uring_cmd_may_sleep(u32 cmd_op)
static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd,
unsigned int issue_flags)
{
- const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
+ const struct ublksrv_ctrl_cmd *header = io_uring_sqe128_cmd(cmd->sqe,
+ struct ublksrv_ctrl_cmd);
struct ublk_device *ub = NULL;
u32 cmd_op = cmd->cmd_op;
int ret = -EINVAL;
diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index fb62633ccbb0..8844bbd39515 100644
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -447,7 +447,8 @@ static int nvme_uring_cmd_io(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
struct io_uring_cmd *ioucmd, unsigned int issue_flags, bool vec)
{
struct nvme_uring_cmd_pdu *pdu = nvme_uring_cmd_pdu(ioucmd);
- const struct nvme_uring_cmd *cmd = io_uring_sqe_cmd(ioucmd->sqe);
+ const struct nvme_uring_cmd *cmd = io_uring_sqe128_cmd(ioucmd->sqe,
+ struct nvme_uring_cmd);
struct request_queue *q = ns ? ns->queue : ctrl->admin_q;
struct nvme_uring_data d;
struct nvme_command c;
diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
index 5ceb217ced1b..60f2058feb74 100644
--- a/fs/fuse/dev_uring.c
+++ b/fs/fuse/dev_uring.c
@@ -879,7 +879,8 @@ static int fuse_ring_ent_set_commit(struct fuse_ring_ent *ent)
static int fuse_uring_commit_fetch(struct io_uring_cmd *cmd, int issue_flags,
struct fuse_conn *fc)
{
- const struct fuse_uring_cmd_req *cmd_req = io_uring_sqe_cmd(cmd->sqe);
+ const struct fuse_uring_cmd_req *cmd_req = io_uring_sqe128_cmd(cmd->sqe,
+ struct fuse_uring_cmd_req);
struct fuse_ring_ent *ent;
int err;
struct fuse_ring *ring = fc->ring;
@@ -1083,7 +1084,8 @@ fuse_uring_create_ring_ent(struct io_uring_cmd *cmd,
static int fuse_uring_register(struct io_uring_cmd *cmd,
unsigned int issue_flags, struct fuse_conn *fc)
{
- const struct fuse_uring_cmd_req *cmd_req = io_uring_sqe_cmd(cmd->sqe);
+ const struct fuse_uring_cmd_req *cmd_req = io_uring_sqe128_cmd(cmd->sqe,
+ struct fuse_uring_cmd_req);
struct fuse_ring *ring = smp_load_acquire(&fc->ring);
struct fuse_ring_queue *queue;
struct fuse_ring_ent *ent;
diff --git a/include/linux/io_uring/cmd.h b/include/linux/io_uring/cmd.h
index 375fd048c4cb..7245b975c55d 100644
--- a/include/linux/io_uring/cmd.h
+++ b/include/linux/io_uring/cmd.h
@@ -20,10 +20,17 @@ struct io_uring_cmd {
u8 unused[8];
};
-static inline const void *io_uring_sqe_cmd(const struct io_uring_sqe *sqe)
-{
- return sqe->cmd;
-}
+#define io_uring_sqe128_cmd(sqe, type) ({ \
+ BUILD_BUG_ON(sizeof(type) > ((2 * sizeof(struct io_uring_sqe)) - \
+ offsetof(struct io_uring_sqe, cmd))); \
+ (const type *)(sqe)->cmd; \
+})
+
+#define io_uring_sqe_cmd(sqe, type) ({ \
+ BUILD_BUG_ON(sizeof(type) > ((sizeof(struct io_uring_sqe)) - \
+ offsetof(struct io_uring_sqe, cmd))); \
+ (const type *)(sqe)->cmd; \
+})
static inline void io_uring_cmd_private_sz_check(size_t cmd_sz)
{
--
2.52.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] io_uring: Add size check for sqe->cmd
2026-01-29 23:54 [PATCH v2] io_uring: Add size check for sqe->cmd Govindarajulu Varadarajan
@ 2026-01-30 1:27 ` Caleb Sander Mateos
0 siblings, 0 replies; 2+ messages in thread
From: Caleb Sander Mateos @ 2026-01-30 1:27 UTC (permalink / raw)
To: Govindarajulu Varadarajan
Cc: io-uring, axboe, ming.lei, kbusch, hch, sagi, miklos
On Thu, Jan 29, 2026 at 3:55 PM Govindarajulu Varadarajan
<govind.varadar@gmail.com> wrote:
>
> For SQE128, sqe->cmd provides 80 bytes for uring_cmd. Add macro to
> check if size of user struct does not exceed 80 bytes at compile time.
> User doesn't have to track this manually during development.
>
> Replace io_uring_sqe_cmd() inline func with macro and add
> io_uring_sqe128_cmd() which checks struct
> size for 16 bytes cmd and 80 bytes cmd respectively.
>
> Signed-off-by: Govindarajulu Varadarajan <govind.varadar@gmail.com>
> ---
> v2:
> - Replace all caps macro with lower case definition.
> - Add const qualifier to return type.
> - Rebase on top of series "[PATCH 0/4] ublk: fix struct
> ublksrv_ctrl_cmd accesses"
>
> BRANCH: for-7.0/block
>
> Depends-on series: "[PATCH 0/4] ublk: fix struct ublksrv_ctrl_cmd
> accesses"
> Needs "[PATCH 2/4] ublk: don't write to struct ublksrv_ctrl_cmd" to
> avoid merge conflict.
> ---
> drivers/block/ublk_drv.c | 14 +++++++++-----
> drivers/nvme/host/ioctl.c | 3 ++-
> fs/fuse/dev_uring.c | 6 ++++--
> include/linux/io_uring/cmd.h | 15 +++++++++++----
> 4 files changed, 26 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
> index 0e25a59849ae..3f9d6dc3afef 100644
> --- a/drivers/block/ublk_drv.c
> +++ b/drivers/block/ublk_drv.c
> @@ -3244,7 +3244,8 @@ static int ublk_ch_uring_cmd_local(struct io_uring_cmd *cmd,
> unsigned int issue_flags)
> {
> /* May point to userspace-mapped memory */
> - const struct ublksrv_io_cmd *ub_src = io_uring_sqe_cmd(cmd->sqe);
> + const struct ublksrv_io_cmd *ub_src = io_uring_sqe_cmd(cmd->sqe,
> + struct ublksrv_io_cmd);
> u16 buf_idx = UBLK_INVALID_BUF_IDX;
> struct ublk_device *ub = cmd->file->private_data;
> struct ublk_queue *ubq;
> @@ -3824,7 +3825,8 @@ static int ublk_validate_batch_fetch_cmd(struct ublk_batch_io_data *data)
> static int ublk_handle_non_batch_cmd(struct io_uring_cmd *cmd,
> unsigned int issue_flags)
> {
> - const struct ublksrv_io_cmd *ub_cmd = io_uring_sqe_cmd(cmd->sqe);
> + const struct ublksrv_io_cmd *ub_cmd = io_uring_sqe_cmd(cmd->sqe,
> + struct ublksrv_io_cmd);
> struct ublk_device *ub = cmd->file->private_data;
> unsigned tag = READ_ONCE(ub_cmd->tag);
> unsigned q_id = READ_ONCE(ub_cmd->q_id);
> @@ -3853,7 +3855,7 @@ static int ublk_handle_non_batch_cmd(struct io_uring_cmd *cmd,
> static int ublk_ch_batch_io_uring_cmd(struct io_uring_cmd *cmd,
> unsigned int issue_flags)
> {
> - const struct ublk_batch_io *uc = io_uring_sqe_cmd(cmd->sqe);
> + const struct ublk_batch_io *uc = io_uring_sqe_cmd(cmd->sqe, struct ublk_batch_io);
> struct ublk_device *ub = cmd->file->private_data;
> struct ublk_batch_io_data data = {
> .ub = ub,
> @@ -5106,7 +5108,8 @@ static int ublk_char_dev_permission(struct ublk_device *ub,
> static int ublk_ctrl_uring_cmd_permission(struct ublk_device *ub,
> struct io_uring_cmd *cmd, u64 *addr, u16 *len)
> {
> - const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
> + const struct ublksrv_ctrl_cmd *header = io_uring_sqe128_cmd(cmd->sqe,
> + struct ublksrv_ctrl_cmd);
> bool unprivileged = ub->dev_info.flags & UBLK_F_UNPRIVILEGED_DEV;
> void __user *argp = (void __user *)*addr;
> char *dev_path = NULL;
> @@ -5199,7 +5202,8 @@ static bool ublk_ctrl_uring_cmd_may_sleep(u32 cmd_op)
> static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd,
> unsigned int issue_flags)
> {
> - const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
> + const struct ublksrv_ctrl_cmd *header = io_uring_sqe128_cmd(cmd->sqe,
> + struct ublksrv_ctrl_cmd);
> struct ublk_device *ub = NULL;
> u32 cmd_op = cmd->cmd_op;
> int ret = -EINVAL;
> diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
> index fb62633ccbb0..8844bbd39515 100644
> --- a/drivers/nvme/host/ioctl.c
> +++ b/drivers/nvme/host/ioctl.c
> @@ -447,7 +447,8 @@ static int nvme_uring_cmd_io(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
> struct io_uring_cmd *ioucmd, unsigned int issue_flags, bool vec)
> {
> struct nvme_uring_cmd_pdu *pdu = nvme_uring_cmd_pdu(ioucmd);
> - const struct nvme_uring_cmd *cmd = io_uring_sqe_cmd(ioucmd->sqe);
> + const struct nvme_uring_cmd *cmd = io_uring_sqe128_cmd(ioucmd->sqe,
> + struct nvme_uring_cmd);
> struct request_queue *q = ns ? ns->queue : ctrl->admin_q;
> struct nvme_uring_data d;
> struct nvme_command c;
> diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
> index 5ceb217ced1b..60f2058feb74 100644
> --- a/fs/fuse/dev_uring.c
> +++ b/fs/fuse/dev_uring.c
> @@ -879,7 +879,8 @@ static int fuse_ring_ent_set_commit(struct fuse_ring_ent *ent)
> static int fuse_uring_commit_fetch(struct io_uring_cmd *cmd, int issue_flags,
> struct fuse_conn *fc)
> {
> - const struct fuse_uring_cmd_req *cmd_req = io_uring_sqe_cmd(cmd->sqe);
> + const struct fuse_uring_cmd_req *cmd_req = io_uring_sqe128_cmd(cmd->sqe,
> + struct fuse_uring_cmd_req);
> struct fuse_ring_ent *ent;
> int err;
> struct fuse_ring *ring = fc->ring;
> @@ -1083,7 +1084,8 @@ fuse_uring_create_ring_ent(struct io_uring_cmd *cmd,
> static int fuse_uring_register(struct io_uring_cmd *cmd,
> unsigned int issue_flags, struct fuse_conn *fc)
> {
> - const struct fuse_uring_cmd_req *cmd_req = io_uring_sqe_cmd(cmd->sqe);
> + const struct fuse_uring_cmd_req *cmd_req = io_uring_sqe128_cmd(cmd->sqe,
> + struct fuse_uring_cmd_req);
> struct fuse_ring *ring = smp_load_acquire(&fc->ring);
> struct fuse_ring_queue *queue;
> struct fuse_ring_ent *ent;
> diff --git a/include/linux/io_uring/cmd.h b/include/linux/io_uring/cmd.h
> index 375fd048c4cb..7245b975c55d 100644
> --- a/include/linux/io_uring/cmd.h
> +++ b/include/linux/io_uring/cmd.h
> @@ -20,10 +20,17 @@ struct io_uring_cmd {
> u8 unused[8];
> };
>
> -static inline const void *io_uring_sqe_cmd(const struct io_uring_sqe *sqe)
> -{
> - return sqe->cmd;
> -}
> +#define io_uring_sqe128_cmd(sqe, type) ({ \
> + BUILD_BUG_ON(sizeof(type) > ((2 * sizeof(struct io_uring_sqe)) - \
> + offsetof(struct io_uring_sqe, cmd))); \
> + (const type *)(sqe)->cmd; \
> +})
> +
> +#define io_uring_sqe_cmd(sqe, type) ({ \
> + BUILD_BUG_ON(sizeof(type) > ((sizeof(struct io_uring_sqe)) - \
Could remove the extra set of parens around sizeof(struct io_uring_sqe).
Other than that,
Reviewed-by: Caleb Sander Mateos <csander@purestorage.com>
> + offsetof(struct io_uring_sqe, cmd))); \
> + (const type *)(sqe)->cmd; \
> +})
>
> static inline void io_uring_cmd_private_sz_check(size_t cmd_sz)
> {
> --
> 2.52.0
>
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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2026-01-29 23:54 [PATCH v2] io_uring: Add size check for sqe->cmd Govindarajulu Varadarajan
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