linux-kernel - [PATCH] ovl: avoid possible NULL dereference

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Message-Id: <20230925045059.92883-1-suhui@nfschina.com>
Date:   Mon, 25 Sep 2023 12:51:00 +0800
From:   Su Hui <suhui@...china.com>
To:     miklos@...redi.hu, amir73il@...il.com
Cc:     Su Hui <suhui@...china.com>, linux-unionfs@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [PATCH] ovl: avoid possible NULL dereference

smatch warn:
fs/overlayfs/copy_up.c:450 ovl_set_origin() warn:
variable dereferenced before check 'fh' (see line 449)

If 'fh' is NULL, passing NULL instead of 'fh->buf'.

Signed-off-by: Su Hui <suhui@...china.com>
---
 fs/overlayfs/copy_up.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index d1761ec5866a..086f9176b4d4 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -446,7 +446,7 @@ int ovl_set_origin(struct ovl_fs *ofs, struct dentry *lower,
 	/*
 	 * Do not fail when upper doesn't support xattrs.
 	 */
-	err = ovl_check_setxattr(ofs, upper, OVL_XATTR_ORIGIN, fh->buf,
+	err = ovl_check_setxattr(ofs, upper, OVL_XATTR_ORIGIN, fh ? fh->buf : NULL,
 				 fh ? fh->fb.len : 0, 0);
 	kfree(fh);
 
-- 
2.30.2