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dma-debug: Fix check_unmap null pointer dereference

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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>
This commit is contained in:
Kyle McMartin 2009-08-19 21:17:08 -04:00 committed by Ingo Molnar
parent 429966b8f6
commit ec9c96ef3c
1 changed files with 16 additions and 12 deletions
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28
lib/dma-debug.c
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@ -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;
@ -183,17 +187,17 @@ static bool driver_filter(struct device *dev)
return ret;
}
#define err_printk(dev, entry, format, arg...) do { \
error_count += 1; \
if (driver_filter(dev) && \
(show_all_errors || show_num_errors > 0)) { \
WARN(1, "%s %s: " format, \
dev_driver_string(dev), \
dev_name(dev) , ## arg); \
dump_entry_trace(entry); \
} \
if (!show_all_errors && show_num_errors > 0) \
show_num_errors -= 1; \
#define err_printk(dev, entry, format, arg...) do { \
error_count += 1; \
if (driver_filter(dev) && \
(show_all_errors || show_num_errors > 0)) { \
WARN(1, "%s %s: " format, \
dev ? dev_driver_string(dev) : "NULL", \
dev ? dev_name(dev) : "NULL", ## arg); \
dump_entry_trace(entry); \
} \
if (!show_all_errors && show_num_errors > 0) \
show_num_errors -= 1; \
} while (0);
/*