From: Hyejeong Choi <hjeong.choi@samsung.com> mainline inclusion from mainline-v6.12-rc1 commit 72c7d62583ebce7baeb61acce6057c361f73be4a category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/ICJTDA CVE: CVE-2025-38095 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- smp_store_mb() inserts memory barrier after storing operation. It is different with what the comment is originally aiming so Null pointer dereference can be happened if memory update is reordered. Signed-off-by: Hyejeong Choi <hjeong.choi@samsung.com> Fixes: a590d0fdbaa5 ("dma-buf: Update reservation shared_count after adding the new fence") CC: stable@vger.kernel.org Reviewed-by: Christian König <christian.koenig@amd.com> Link: https://lore.kernel.org/r/20250513020638.GA2329653@au1-maretx-p37.eng.sarc.s... Signed-off-by: Christian König <christian.koenig@amd.com> Conflicts: drivers/dma-buf/dma-resv.c [Context conflict] Signed-off-by: Bowen You <youbowen2@huawei.com> --- drivers/dma-buf/dma-resv.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c index eb8b733065b2..9093f751f133 100644 --- a/drivers/dma-buf/dma-resv.c +++ b/drivers/dma-buf/dma-resv.c @@ -313,8 +313,9 @@ void dma_resv_add_fence(struct dma_resv *obj, struct dma_fence *fence, count++; dma_resv_list_set(fobj, i, fence, usage); - /* pointer update must be visible before we extend the num_fences */ - smp_store_mb(fobj->num_fences, count); + /* fence update must be visible before we extend the num_fences */ + smp_wmb(); + fobj->num_fences = count; } EXPORT_SYMBOL(dma_resv_add_fence); -- 2.34.1