yaffs: replace IS_ERR with IS_ERR_OR_NULL to check both ERR and NULL

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Author: Meng Li
Email: Meng.Li@windriver.com
Subject: yaffs: replace IS_ERR with IS_ERR_OR_NULL to check both ERR and NULL
Date: Thu, 21 Oct 2021 09:27:20 +0800

When run below command to mount a yaffs2 FS to nor flash, there
is kernel panic as below:
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000020
......
Internal error: Oops: 96000004 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 335 Comm: mount Not tainted 5.10.73-yocto-standard #1
......
Call trace:
 yaffs_internal_read_super.constprop.0+0x24c/0x6fc
 yaffs2_internal_read_super_mtd+0x28/0x40
 mount_bdev+0x1cc/0x200
 ......
 el0_sync_handler+0x1a4/0x1b0
 el0_sync+0x180/0x1c0
Because in function yaffs_get_mtd_device(), it check the type of
mtd device. If it is not NAND flash, NULL will be returned. This
causes kernel panic if the ret value is not checked whether it
is NULL or not. So, replace IS_ERR with IS_ERR_OR_NULL to check
both ERR and NULL.

Signed-off-by: Meng Li <Meng.Li@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
]
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>

features/yaffs2/yaffs-replace-IS_ERR-with-IS_ERR_OR_NULL-to-check-bo.patch

+From a8f317c1a17e3cab01708912f09c5e8fbc3702dc Mon Sep 17 00:00:00 2001
+From: Meng Li <Meng.Li@windriver.com>
+Date: Thu, 21 Oct 2021 09:27:20 +0800
+Subject: [PATCH] yaffs: replace IS_ERR with IS_ERR_OR_NULL to check both ERR
+ and NULL
+
+When run below command to mount a yaffs2 FS to nor flash, there
+is kernel panic as below:
+Unable to handle kernel NULL pointer dereference at virtual address 0000000000000020
+......
+Internal error: Oops: 96000004 [#1] PREEMPT SMP
+Modules linked in:
+CPU: 1 PID: 335 Comm: mount Not tainted 5.10.73-yocto-standard #1
+......
+Call trace:
+ yaffs_internal_read_super.constprop.0+0x24c/0x6fc
+ yaffs2_internal_read_super_mtd+0x28/0x40
+ mount_bdev+0x1cc/0x200
+ ......
+ el0_sync_handler+0x1a4/0x1b0
+ el0_sync+0x180/0x1c0
+Because in function yaffs_get_mtd_device(), it check the type of
+mtd device. If it is not NAND flash, NULL will be returned. This
+causes kernel panic if the ret value is not checked whether it
+is NULL or not. So, replace IS_ERR with IS_ERR_OR_NULL to check
+both ERR and NULL.
+
+Signed-off-by: Meng Li <Meng.Li@windriver.com>
+Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
+---
+ fs/yaffs2/yaffs_vfs.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/fs/yaffs2/yaffs_vfs.c b/fs/yaffs2/yaffs_vfs.c
+index a9cf8edc2245..eeb1b480d70e 100644
+--- a/fs/yaffs2/yaffs_vfs.c
++++ b/fs/yaffs2/yaffs_vfs.c
+@@ -2964,7 +2964,7 @@ static struct super_block *yaffs_internal_read_super(int yaffs_version,
+ 
+ 
+ 	mtd = yaffs_get_mtd_device(sb->s_dev);
+-	if (IS_ERR(mtd)) {
++	if (IS_ERR_OR_NULL(mtd)) {
+ 		return NULL;
+ 	}
+ 
+-- 
+2.19.1
+

features/yaffs2/yaffs2.scc

@@ -13,3 +13,4 @@ patch yaffs2-v5.6-build-fixups.patch
 patch yaffs-fix-misplaced-variable-declaration.patch
 patch yaffs-include-blkdev.h.patch
 patch yaffs-fix-Wstringop-overread-compile-warning-in-yaff.patch
+patch yaffs-replace-IS_ERR-with-IS_ERR_OR_NULL-to-check-bo.patch