Danilo Krummrich
2024-Mar-05 13:40 UTC
[PATCH] nouveau/dmem: handle kcalloc() allocation failure
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 at zju.edu.cn> > --- > 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