Re: [PATCH] nouveau/dmem: handle kcalloc() allocation failure

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi Duoming,

On 3/3/24 08:53, Duoming Zhou wrote:
The kcalloc() in nouveau_dmem_evict_chunk() will return null if
the physical memory has run out. As a result, if we dereference
src_pfns, dst_pfns or dma_addrs, the null pointer dereference bugs
will happen.

This patch uses stack variables to replace the kcalloc().

Fixes: 249881232e14 ("nouveau/dmem: evict device private memory during release")
Signed-off-by: Duoming Zhou <duoming@xxxxxxxxxx>
---
  drivers/gpu/drm/nouveau/nouveau_dmem.c | 13 +++++--------
  1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c
index 12feecf71e7..9a578262c6d 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
@@ -374,13 +374,13 @@ static void
  nouveau_dmem_evict_chunk(struct nouveau_dmem_chunk *chunk)
  {
  	unsigned long i, npages = range_len(&chunk->pagemap.range) >> PAGE_SHIFT;
-	unsigned long *src_pfns, *dst_pfns;
-	dma_addr_t *dma_addrs;
+	unsigned long src_pfns[npages], dst_pfns[npages];
+	dma_addr_t dma_addrs[npages];

Please don't use variable length arrays, this can potentially blow up
the stack.

As a fix I think we should allocate with __GFP_NOFAIL instead.

- Danilo

  	struct nouveau_fence *fence;
- src_pfns = kcalloc(npages, sizeof(*src_pfns), GFP_KERNEL);
-	dst_pfns = kcalloc(npages, sizeof(*dst_pfns), GFP_KERNEL);
-	dma_addrs = kcalloc(npages, sizeof(*dma_addrs), GFP_KERNEL);
+	memset(src_pfns, 0, npages);
+	memset(dst_pfns, 0, npages);
+	memset(dma_addrs, 0, npages);
migrate_device_range(src_pfns, chunk->pagemap.range.start >> PAGE_SHIFT,
  			npages);
@@ -406,11 +406,8 @@ nouveau_dmem_evict_chunk(struct nouveau_dmem_chunk *chunk)
  	migrate_device_pages(src_pfns, dst_pfns, npages);
  	nouveau_dmem_fence_done(&fence);
  	migrate_device_finalize(src_pfns, dst_pfns, npages);
-	kfree(src_pfns);
-	kfree(dst_pfns);
  	for (i = 0; i < npages; i++)
  		dma_unmap_page(chunk->drm->dev->dev, dma_addrs[i], PAGE_SIZE, DMA_BIDIRECTIONAL);
-	kfree(dma_addrs);
  }
void




[Index of Archives]     [Linux DRI Users]     [Linux Intel Graphics]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]
  Powered by Linux