From: Shuai Xue xueshuai@linux.alibaba.com

mainline inclusion from mainline-v6.0 commit 77677cdbc2aa4b5d5d839562793d3d126201d18d category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IB5LNL

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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The GHES code calls memory_failure_queue() from IRQ context to queue work into workqueue and schedule it on the current CPU. Then the work is processed in memory_failure_work_func() by kworker and calls memory_failure().

When a page is already poisoned, commit a3f5d80ea401 ("mm,hwpoison: send SIGBUS with error virutal address") make memory_failure() call kill_accessing_process() that:

- holds mmap locking of current->mm - does pagetable walk to find the error virtual address - and sends SIGBUS to the current process with error info.

However, the mm of kworker is not valid, resulting in a null-pointer dereference. So check mm when killing the accessing process.

[akpm@linux-foundation.org: remove unrelated whitespace alteration] Link: https://lkml.kernel.org/r/20220914064935.7851-1-xueshuai@linux.alibaba.com Fixes: a3f5d80ea401 ("mm,hwpoison: send SIGBUS with error virutal address") Signed-off-by: Shuai Xue xueshuai@linux.alibaba.com Reviewed-by: Miaohe Lin linmiaohe@huawei.com Acked-by: Naoya Horiguchi naoya.horiguchi@nec.com Cc: Huang Ying ying.huang@intel.com Cc: Baolin Wang baolin.wang@linux.alibaba.com Cc: Bixuan Cui cuibixuan@linux.alibaba.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Ma Wupeng mawupeng1@huawei.com --- mm/memory-failure.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 90daab0c8b96..a5ab0b2f213b 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -692,6 +692,9 @@ static int kill_accessing_process(struct task_struct *p, unsigned long pfn, }; priv.tk.tsk = p;

+ if (!p->mm) + return -EFAULT; + mmap_read_lock(p->mm); ret = walk_page_range(p->mm, 0, TASK_SIZE, &hwp_walk_ops, (void *)&priv);