[PATCH 5.15 34/83] mm,hwpoison: check mm when killing accessing process

Greg Kroah-Hartman
2022-10-03T07:45:45Z

From: Shuai Xue <xueshuai@linux.alibaba.com>

commit 77677cdbc2aa4b5d5d839562793d3d126201d18d upstream.

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
mm/memory-failure.c | 3 +++
1 file changed, 3 insertions(+)

--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -700,6 +700,9 @@ static int kill_accessing_process(struct
};
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);