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Commit 8d640a51 authored by Alexander Duyck's avatar Alexander Duyck Committed by Linus Torvalds
Browse files

dma-debug: fix locking bug in check_unmap() 



In check_unmap() it is possible to get into a dead-locked state if
dma_mapping_error is called.  The problem is that the bucket is locked in
check_unmap, and locked again by debug_dma_mapping_error which is called
by dma_mapping_error.  To resolve that we must release the lock on the
bucket before making the call to dma_mapping_error.

[akpm@linux-foundation.org: restore 80-col trickery to be consistent with the rest of the file]
Signed-off-by: default avatarAlexander Duyck <alexander.h.duyck@intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Reviewed-by: default avatarShuah Khan <shuah.khan@hp.com>
Tested-by: default avatarShuah Khan <shuah.khan@hp.com>
Cc: Jakub Kicinski <kubakici@wp.pl>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 0ef1594c

lib/dma-debug.c

+12 −9
Original line number Diff line number Diff line
@@ -862,17 +862,21 @@ static void check_unmap(struct dma_debug_entry *ref) 
	entry = bucket_find_exact(bucket, ref);



	if (!entry) {

		/* must drop lock before calling dma_mapping_error */

		put_hash_bucket(bucket, &flags);



		if (dma_mapping_error(ref->dev, ref->dev_addr)) {

			err_printk(ref->dev, NULL,

				   "DMA-API: device driver tries "

				   "to free an invalid DMA memory address\n");

			return;

		}

		err_printk(ref->dev, NULL, "DMA-API: device driver tries "

			   "to free DMA memory it has not allocated "

			   "[device address=0x%016llx] [size=%llu bytes]\n",

				   "DMA-API: device driver tries to free an "

				   "invalid DMA memory address\n");

		} else {

			err_printk(ref->dev, NULL,

				   "DMA-API: device driver tries to free DMA "

				   "memory it has not allocated [device "

				   "address=0x%016llx] [size=%llu bytes]\n",

				   ref->dev_addr, ref->size);

		goto out;

		}

		return;

	}



	if (ref->size != entry->size) {
@@ -936,7 +940,6 @@ static void check_unmap(struct dma_debug_entry *ref) 
	hash_bucket_del(entry);

	dma_entry_free(entry);



out:

	put_hash_bucket(bucket, &flags);

}