Re: [PATCH] swiotlb: Fix uninitialized pointer on DMA ops

From: Robin Murphy
Date: Mon Aug 20 2018 - 06:00:35 EST

On 18/08/18 20:04, Esteban Zamora wrote:
The mmap function pointer on swiotlb_dma_ops struct is
uninitialized, which causes a random crash when calling
the dma_mmap_coherent function on platforms where no DMA
address translation hardware is available.

Can you share any kernel logs with details of those crashes? As Konrad mentions, the rules for partial structure initialisation in C are well-defined, even with designated initialisers[1], and if this commit message were true then half of the subsystems in the kernel would be crashing left right and centre.



Set this pointer to NULL in order to fix the issue.

Signed-off-by: Esteban Zamora <estebanzacr.20@xxxxxxxxx>
kernel/dma/swiotlb.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 4f8a6db..9a7718c 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -1082,5 +1082,6 @@ const struct dma_map_ops swiotlb_dma_ops = {
.map_page = swiotlb_map_page,
.unmap_page = swiotlb_unmap_page,
.dma_supported = dma_direct_supported,
+ .mmap = NULL,