linux-kernel - [PATCH 6/6] erofs: use poison pointer to replace the hard-coded address

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Date:   Sat, 27 May 2023 04:14:59 +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>
Subject: [PATCH 6/6] erofs: use poison pointer to replace the hard-coded address

It's safer and cleaner to replace such hard-coded illegal pointer
with poison pointers.

Signed-off-by: Gao Xiang <hsiangkao@...ux.alibaba.com>
---
 fs/erofs/zdata.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 2ea8e7f08372..83df1954b859 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -91,10 +91,8 @@ struct z_erofs_pcluster {
 	struct z_erofs_bvec compressed_bvecs[];
 };
 
-/* let's avoid the valid 32-bit kernel addresses */
-
 /* the end of a chain of pclusters */
-#define Z_EROFS_PCLUSTER_TAIL           ((void *)0x5F0ECAFE)
+#define Z_EROFS_PCLUSTER_TAIL           ((void *) 0x700 + POISON_POINTER_DELTA)
 #define Z_EROFS_PCLUSTER_NIL            (NULL)
 
 struct z_erofs_decompressqueue {
-- 
2.24.4