[PATCH] erofs: fix wrong kunmap when using LZMA on HIGHMEM platforms

[Chao Yu]

On 2023/3/5 21:44, Gao Xiang 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 at vger.kernel.org> # 5.16+
> Signed-off-by: Gao Xiang <hsiangkao at linux.alibaba.com>

Reviewed-by: Chao Yu <chao at kernel.org>

Thanks,