linux-kernel - [PATCH] AFS: Fix the module init error handling

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Message-ID: <20100806162648.11782.17953.stgit@warthog.procyon.org.uk>
Date:	Fri, 06 Aug 2010 17:26:48 +0100
From:	David Howells <dhowells@...hat.com>
To:	torvalds@...l.org, akpm@...ux-foundation.org
Cc:	linux-afs@...ts.infradead.org, linux-kernel@...r.kernel.org,
	David Howells <dhowells@...hat.com>
Subject: [PATCH] AFS: Fix the module init error handling

Fix the module init error handling.  There are a bunch of goto labels for
aborting the init procedure at different points and just undoing what needs
undoing - they aren't all in the right places, however.

This can lead to an oops like the following:

	BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
	IP: [<ffffffff81042a31>] destroy_workqueue+0x17/0xc0
	...
	Modules linked in: kafs(+) dns_resolver rxkad af_rxrpc fscache

	Pid: 2171, comm: insmod Not tainted 2.6.35-cachefs+ #319 DG965RY/
	...
	Process insmod (pid: 2171, threadinfo ffff88003ca6a000, task ffff88003dcc3050)
	...
	Call Trace:
	 [<ffffffffa0055994>] afs_callback_update_kill+0x10/0x12 [kafs]
	 [<ffffffffa007d1c5>] afs_init+0x190/0x1ce [kafs]
	 [<ffffffffa007d035>] ? afs_init+0x0/0x1ce [kafs]
	 [<ffffffff810001ef>] do_one_initcall+0x59/0x14e
	 [<ffffffff8105f7ee>] sys_init_module+0x9c/0x1de
	 [<ffffffff81001eab>] system_call_fastpath+0x16/0x1b

Signed-off-by: David Howells <dhowells@...hat.com>
---

 fs/afs/main.c |    9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/afs/main.c b/fs/afs/main.c
index 66d54d3..cfd1cbe 100644
--- a/fs/afs/main.c
+++ b/fs/afs/main.c
@@ -111,6 +111,8 @@ static int __init afs_init(void)
 
 	/* initialise the callback update process */
 	ret = afs_callback_update_init();
+	if (ret < 0)
+		goto error_callback_update_init;
 
 	/* create the RxRPC transport */
 	ret = afs_open_socket();
@@ -127,15 +129,16 @@ static int __init afs_init(void)
 error_fs:
 	afs_close_socket();
 error_open_socket:
+	afs_callback_update_kill();
+error_callback_update_init:
+	afs_vlocation_purge();
 error_vl_update_init:
+	afs_cell_purge();
 error_cell_init:
 #ifdef CONFIG_AFS_FSCACHE
 	fscache_unregister_netfs(&afs_cache_netfs);
 error_cache:
 #endif
-	afs_callback_update_kill();
-	afs_vlocation_purge();
-	afs_cell_purge();
 	afs_proc_cleanup();
 	rcu_barrier();
 	printk(KERN_ERR "kAFS: failed to register: %d\n", ret);

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