Commit ec9c96ef authored Aug 19, 2009 by Kyle McMartin Committed by Ingo Molnar Aug 21, 2009

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: Kyle 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: Ingo Molnar <mingo@elte.hu>

parent 429966b8

lib/dma-debug.c

+16 −12

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

		/* driver filter on and initialized */
		if (current_driver && dev->driver == current_driver)
		if (current_driver && dev && dev->driver == current_driver)
		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])
		return false;

		@@ -188,8 +192,8 @@ static bool driver_filter(struct device *dev)
		if (driver_filter(dev) && \
		(show_all_errors \|\| show_num_errors > 0)) { \
		WARN(1, "%s %s: " format, \
		dev_driver_string(dev), \
		dev_name(dev) , ## arg); \
		dev ? dev_driver_string(dev) : "NULL", \
		dev ? dev_name(dev) : "NULL", ## arg); \
		dump_entry_trace(entry); \
		} \
		if (!show_all_errors && show_num_errors > 0) \

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