[PATCH] tipc: Don't using smp_processor_id() in preemptible code

[PATCH] tipc: Don't using smp_processor_id() in preemptible code

[qiang.zhang]

From: Zhang Qiang <qiang.zhang@windriver.com>

CPU: 0 PID: 6801 Comm: syz-executor201 Not tainted 5.8.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine,
BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18f/0x20d lib/dump_stack.c:118
 check_preemption_disabled+0x128/0x130 lib/smp_processor_id.c:48
 tipc_aead_tfm_next net/tipc/crypto.c:402 [inline]
 tipc_aead_encrypt net/tipc/crypto.c:639 [inline]
 tipc_crypto_xmit+0x80a/0x2790 net/tipc/crypto.c:1605
 tipc_bearer_xmit_skb+0x180/0x3f0 net/tipc/bearer.c:523
 tipc_enable_bearer+0xb1d/0xdc0 net/tipc/bearer.c:331
 __tipc_nl_bearer_enable+0x2bf/0x390 net/tipc/bearer.c:995
 __tipc_nl_compat_doit net/tipc/netlink_compat.c:361 [inline]
 tipc_nl_compat_doit+0x440/0x640 net/tipc/netlink_compat.c:383
 tipc_nl_compat_handle net/tipc/netlink_compat.c:1268 [inline]
 tipc_nl_compat_recv+0x4ef/0xb40 net/tipc/netlink_compat.c:1311
 genl_family_rcv_msg_doit net/netlink/genetlink.c:669 [inline]
 genl_family_rcv_msg net/netlink/genetlink.c:714 [inline]
 genl_rcv_msg+0x61d/0x980 net/netlink/genetlink.c:731
 netlink_rcv_skb+0x15a/0x430 net/netlink/af_netlink.c:2469
 genl_rcv+0x24/0x40 net/netlink/genetlink.c:742
 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1329
 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2352
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2406
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x4476a9
Code: Bad RIP value.
RSP: 002b:00007fff2b6d5168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 000000000000

Reported-by: syzbot+263f8c0d007dc09b2dda@syzkaller.appspotmail.com
Signed-off-by: Zhang Qiang <qiang.zhang@windriver.com>
---
 net/tipc/crypto.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
index 8c47ded2edb6..520af0afe1b3 100644
--- a/net/tipc/crypto.c
+++ b/net/tipc/crypto.c
@@ -399,9 +399,10 @@ static void tipc_aead_users_set(struct tipc_aead __rcu *aead, int val)
  */
 static struct crypto_aead *tipc_aead_tfm_next(struct tipc_aead *aead)
 {
-	struct tipc_tfm **tfm_entry = this_cpu_ptr(aead->tfm_entry);
+	struct tipc_tfm **tfm_entry = get_cpu_ptr(aead->tfm_entry);
 
 	*tfm_entry = list_next_entry(*tfm_entry, list);
+	put_cpu_ptr(tfm_entry);
 	return (*tfm_entry)->tfm;
 }
 
-- 
2.24.1

Re: [PATCH] tipc: Don't using smp_processor_id() in preemptible code

[Eric Dumazet]

On 7/13/20 6:53 PM, qiang.zhang@windriver.com wrote:
> From: Zhang Qiang <qiang.zhang@windriver.com>
> 
> CPU: 0 PID: 6801 Comm: syz-executor201 Not tainted 5.8.0-rc4-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine,
> BIOS Google 01/01/2011
>
> Reported-by: syzbot+263f8c0d007dc09b2dda@syzkaller.appspotmail.com
> Signed-off-by: Zhang Qiang <qiang.zhang@windriver.com>
> ---
>  net/tipc/crypto.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
> index 8c47ded2edb6..520af0afe1b3 100644
> --- a/net/tipc/crypto.c
> +++ b/net/tipc/crypto.c
> @@ -399,9 +399,10 @@ static void tipc_aead_users_set(struct tipc_aead __rcu *aead, int val)
>   */
>  static struct crypto_aead *tipc_aead_tfm_next(struct tipc_aead *aead)
>  {
> -	struct tipc_tfm **tfm_entry = this_cpu_ptr(aead->tfm_entry);
> +	struct tipc_tfm **tfm_entry = get_cpu_ptr(aead->tfm_entry);
>  
>  	*tfm_entry = list_next_entry(*tfm_entry, list);
> +	put_cpu_ptr(tfm_entry);
>  	return (*tfm_entry)->tfm;
>  }
>  
> 

This seems to hide a real bug.

Presumably callers of this function should have disable preemption, and maybe interrupts as well.

In any case, a Fixes: tag would be welcomed.