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Commit ec9c96ef authored by Kyle McMartin's avatar Kyle McMartin Committed by Ingo Molnar
Browse files

dma-debug: Fix check_unmap null pointer dereference 



While it's debatable whether or not a NULL device argument to
the DMA API functions is valid... since it certainly isn't
valid on devices with an IOMMU... dma-debug really shouldn't be
dereferencing null pointers either.

Guard against that in err_printk and the driver_filter
functions. A Fedora rawhide user was seeing this in one of the
dvb drivers resulting in an oops on boot.

[ A patch has been sent for testing to the driver, but I feel
  the dma debugging support should be fixed as well. (There's
  still a pile of legacy garbage in the kernel passing null
  pointers to dma_{alloc,free}_*. :( ]

Signed-off-by: default avatarKyle McMartin <kyle@redhat.com>
Cc: mchehab@infradead.org
Cc: Joerg Roedel <joerg.roedel@amd.com>
LKML-Reference: <20090820011708.GP25206@bombadil.infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 429966b8

lib/dma-debug.c

+16 −12
Original line number Original line Diff line number Diff line
@@ -156,9 +156,13 @@ static bool driver_filter(struct device *dev) 
		return true;

		return true;





	/* driver filter on and initialized */

	/* driver filter on and initialized */

	if (current_driver && dev->driver == current_driver)

	if (current_driver && dev && dev->driver == current_driver)

		return true;

		return true;





	/* driver filter on, but we can't filter on a NULL device... */

	if (!dev)

		return false;



	if (current_driver || !current_driver_name[0])

	if (current_driver || !current_driver_name[0])

		return false;

		return false;
@@ -188,8 +192,8 @@ static bool driver_filter(struct device *dev) 
		if (driver_filter(dev) &&				\

		if (driver_filter(dev) &&				\

		    (show_all_errors || show_num_errors > 0)) {		\

		    (show_all_errors || show_num_errors > 0)) {		\

			WARN(1, "%s %s: " format,			\

			WARN(1, "%s %s: " format,			\

			     dev_driver_string(dev),		\

			     dev ? dev_driver_string(dev) : "NULL",	\

			     dev_name(dev) , ## arg);		\

			     dev ? dev_name(dev) : "NULL", ## arg);	\

			dump_entry_trace(entry);			\

			dump_entry_trace(entry);			\

		}							\

		}							\

		if (!show_all_errors && show_num_errors > 0)		\

		if (!show_all_errors && show_num_errors > 0)		\