Re: [patch v18 1/4] drivers: jtag: Add JTAG core driver

On Mon, Jan 29, 2018 at 04:31:42PM +0200, Oleksandr Shamray wrote:

Initial patch for JTAG driver
JTAG class driver provide infrastructure to support hardware/software
JTAG platform drivers. It provide user layer API interface for flashing
and debugging external devices which equipped with JTAG interface
using standard transactions.

Driver exposes set of IOCTL to user space for:
- XFER:
- SIR (Scan Instruction Register, IEEE 1149.1 Data Register scan);
- SDR (Scan Data Register, IEEE 1149.1 Instruction Register scan);
- RUNTEST (Forces the IEEE 1149.1 bus to a run state for a specified
  number of clocks).
- SIOCFREQ/GIOCFREQ for setting and reading JTAG frequency.

Driver core provides set of internal APIs for allocation and
registration:
- jtag_register;
- jtag_unregister;
- jtag_alloc;
- jtag_free;

Platform driver on registration with jtag-core creates the next
entry in dev folder:
/dev/jtagX

Signed-off-by: Oleksandr Shamray <oleksandrs-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Signed-off-by: Jiri Pirko <jiri-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Acked-by: Philippe Ombredanne <pombredanne-od1rfyK75/E@public.gmane.org>

[..]

[..]

+struct jtag *jtag_alloc(size_t priv_size, const struct jtag_ops *ops)
+{
+	struct jtag *jtag;
+
+	jtag = kzalloc(sizeof(*jtag) + priv_size, GFP_KERNEL);
+	if (!jtag)
+		return NULL;
+
+	if (!ops)
+		return NULL;
+
+	if (!ops->idle || !ops->mode_set || !ops->status_get || !ops->xfer)
+		return NULL;

Did you think through this?

You leak 'jtag' here and above.

Perform all the ops checks prior to the allocation.

   Julia