5.4-stable review patch. If anyone has any objections, please let me know.
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From: Lance Richardson rlance@google.com
[ Upstream commit 28e8b7406d3a1f5329a03aa25a43aa28e087cb20 ]
dmam_free_coherent() frees a DMA allocation, which makes the freed vaddr available for reuse, then calls devres_destroy() to remove and free the data structure used to track the DMA allocation. Between the two calls, it is possible for a concurrent task to make an allocation with the same vaddr and add it to the devres list.
If this happens, there will be two entries in the devres list with the same vaddr and devres_destroy() can free the wrong entry, triggering the WARN_ON() in dmam_match.
Fix by destroying the devres entry before freeing the DMA allocation.
Tested: kokonut //net/encryption http://sponge2/b9145fe6-0f72-4325-ac2f-a84d81075b03
Fixes: 9ac7849e35f7 ("devres: device resource management") Signed-off-by: Lance Richardson rlance@google.com Signed-off-by: Christoph Hellwig hch@lst.de Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/dma/mapping.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index 8682a5305cb36..942e489bc1fcb 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -59,8 +59,8 @@ void dmam_free_coherent(struct device *dev, size_t size, void *vaddr, { struct dma_devres match_data = { size, vaddr, dma_handle };
- dma_free_coherent(dev, size, vaddr, dma_handle); WARN_ON(devres_destroy(dev, dmam_release, dmam_match, &match_data)); + dma_free_coherent(dev, size, vaddr, dma_handle); } EXPORT_SYMBOL(dmam_free_coherent);