On Sun, 5 Mar 2023 21:44:55 +0800 Gao Xiang hsiangkao@linux.alibaba.com wrote:

As the call trace shown, the root cause is kunmap incorrect pages:

BUG: kernel NULL pointer dereference, address: 00000000 CPU: 1 PID: 40 Comm: kworker/u5:0 Not tainted 6.2.0-rc5 #4 Workqueue: erofs_worker z_erofs_decompressqueue_work EIP: z_erofs_lzma_decompress+0x34b/0x8ac z_erofs_decompress+0x12/0x14 z_erofs_decompress_queue+0x7e7/0xb1c z_erofs_decompressqueue_work+0x32/0x60 process_one_work+0x24b/0x4d8 ? process_one_work+0x1a4/0x4d8 worker_thread+0x14c/0x3fc kthread+0xe6/0x10c ? rescuer_thread+0x358/0x358 ? kthread_complete_and_exit+0x18/0x18 ret_from_fork+0x1c/0x28 ---[ end trace 0000000000000000 ]---

The bug is trivial and should be fixed now. It has no impact on !HIGHMEM platforms.

Fixes: 622ceaddb764 ("erofs: lzma compression support") Cc: stable@vger.kernel.org # 5.16+ Signed-off-by: Gao Xiang hsiangkao@linux.alibaba.com

Reviewed-by: Yue Hu huyue2@coolpad.com

---

fs/erofs/decompressor_lzma.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/erofs/decompressor_lzma.c b/fs/erofs/decompressor_lzma.c index 091fd5adf818..5cd612a8f858 100644 --- a/fs/erofs/decompressor_lzma.c +++ b/fs/erofs/decompressor_lzma.c @@ -278,7 +278,7 @@ int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq, } } if (no < nrpages_out && strm->buf.out)

• kunmap(rq->in[no]);
  

• kunmap(rq->out[no]);
  

  if (ni < nrpages_in) kunmap(rq->in[ni]); /* 4. push back LZMA stream context to the global list */