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
