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

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Date:   Sun,  5 Mar 2023 21:44:55 +0800
From:   Gao Xiang <hsiangkao@...ux.alibaba.com>
To:     linux-erofs@...ts.ozlabs.org
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Gao Xiang <hsiangkao@...ux.alibaba.com>, stable@...r.kernel.org
Subject: [PATCH] erofs: fix wrong kunmap when using LZMA on HIGHMEM platforms

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@...r.kernel.org> # 5.16+
Signed-off-by: Gao Xiang <hsiangkao@...ux.alibaba.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 */
-- 
2.24.4