linux-kernel - Re: [syzbot] [afs?] general protection fault in afs_atcell_get

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Message-ID: <tencent_DE79B66C942EF56F989538EA7EEC32CD3C0A@qq.com>
Date: Tue, 18 Mar 2025 17:17:14 +0800
From: Edward Adam Davis <eadavis@...com>
To: syzbot+76a6f18e3af82e84f264@...kaller.appspotmail.com
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [afs?] general protection fault in afs_atcell_get_link

#syz test

diff --git a/fs/afs/dynroot.c b/fs/afs/dynroot.c
index 008698d706ca..7d997f7a8028 100644
--- a/fs/afs/dynroot.c
+++ b/fs/afs/dynroot.c
@@ -314,6 +314,9 @@ static const char *afs_atcell_get_link(struct dentry *dentry, struct inode *inod
 	const char *name;
 	bool dotted = vnode->fid.vnode == 3;
 
+	if (!rcu_access_pointer(net->ws_cell))
+		return ERR_PTR(-ENOENT);
+
 	if (!dentry) {
 		/* We're in RCU-pathwalk. */
 		cell = rcu_dereference(net->ws_cell);
@@ -325,9 +328,6 @@ static const char *afs_atcell_get_link(struct dentry *dentry, struct inode *inod
 		return name;
 	}
 
-	if (!rcu_access_pointer(net->ws_cell))
-		return ERR_PTR(-ENOENT);
-
 	down_read(&net->cells_lock);
 
 	cell = rcu_dereference_protected(net->ws_cell, lockdep_is_held(&net->cells_lock));