6.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: Duoming Zhou <duoming@xxxxxxxxxx> [ Upstream commit c2af060d1c18beaec56351cf9c9bcbbc5af341a3 ] The kcalloc() in dmirror_device_evict_chunk() will return null if the physical memory has run out. As a result, if src_pfns or dst_pfns is dereferenced, the null pointer dereference bug will happen. Moreover, the device is going away. If the kcalloc() fails, the pages mapping a chunk could not be evicted. So add a __GFP_NOFAIL flag in kcalloc(). Finally, as there is no need to have physically contiguous memory, Switch kcalloc() to kvcalloc() in order to avoid failing allocations. Link: https://lkml.kernel.org/r/20240312005905.9939-1-duoming@xxxxxxxxxx Fixes: b2ef9f5a5cb3 ("mm/hmm/test: add selftest driver for HMM") Signed-off-by: Duoming Zhou <duoming@xxxxxxxxxx> Cc: Jérôme Glisse <jglisse@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- lib/test_hmm.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/lib/test_hmm.c b/lib/test_hmm.c index 717dcb8301273..b823ba7cb6a15 100644 --- a/lib/test_hmm.c +++ b/lib/test_hmm.c @@ -1226,8 +1226,8 @@ static void dmirror_device_evict_chunk(struct dmirror_chunk *chunk) unsigned long *src_pfns; unsigned long *dst_pfns; - src_pfns = kcalloc(npages, sizeof(*src_pfns), GFP_KERNEL); - dst_pfns = kcalloc(npages, sizeof(*dst_pfns), GFP_KERNEL); + src_pfns = kvcalloc(npages, sizeof(*src_pfns), GFP_KERNEL | __GFP_NOFAIL); + dst_pfns = kvcalloc(npages, sizeof(*dst_pfns), GFP_KERNEL | __GFP_NOFAIL); migrate_device_range(src_pfns, start_pfn, npages); for (i = 0; i < npages; i++) { @@ -1250,8 +1250,8 @@ static void dmirror_device_evict_chunk(struct dmirror_chunk *chunk) } migrate_device_pages(src_pfns, dst_pfns, npages); migrate_device_finalize(src_pfns, dst_pfns, npages); - kfree(src_pfns); - kfree(dst_pfns); + kvfree(src_pfns); + kvfree(dst_pfns); } /* Removes free pages from the free list so they can't be re-allocated */ -- 2.43.0
