* [PATCH v2] tipc: Don't using smp_processor_id() in preemptible code @ 2020-07-14 8:05 qiang.zhang 2020-07-14 14:15 ` Eric Dumazet 0 siblings, 1 reply; 7+ messages in thread From: qiang.zhang @ 2020-07-14 8:05 UTC (permalink / raw) To: jmaloy, davem, kuba, tuong.t.lien, eric.dumazet, ying.xue Cc: netdev, tipc-discussion, linux-kernel 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 Fixes: fc1b6d6de2208 ("tipc: introduce TIPC encryption & authentication") Reported-by: syzbot+263f8c0d007dc09b2dda@syzkaller.appspotmail.com Signed-off-by: Zhang Qiang <qiang.zhang@windriver.com> --- v1->v2: add fixes tags. 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 ^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH v2] tipc: Don't using smp_processor_id() in preemptible code 2020-07-14 8:05 [PATCH v2] tipc: Don't using smp_processor_id() in preemptible code qiang.zhang @ 2020-07-14 14:15 ` Eric Dumazet 2020-07-15 2:12 ` 回复: " Zhang, Qiang 0 siblings, 1 reply; 7+ messages in thread From: Eric Dumazet @ 2020-07-14 14:15 UTC (permalink / raw) To: qiang.zhang, jmaloy, davem, kuba, tuong.t.lien, eric.dumazet, ying.xue Cc: netdev, tipc-discussion, linux-kernel On 7/14/20 1:05 AM, 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 > > Fixes: fc1b6d6de2208 ("tipc: introduce TIPC encryption & authentication") > Reported-by: syzbot+263f8c0d007dc09b2dda@syzkaller.appspotmail.com > Signed-off-by: Zhang Qiang <qiang.zhang@windriver.com> > --- > v1->v2: > add fixes tags. > > 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; > } > > You have not explained why this was safe. This seems to hide a real bug. Presumably callers of this function should have disable preemption, and maybe interrupts as well. Right after put_cpu_ptr(tfm_entry), this thread could migrate to another cpu, and still access data owned by the old cpu. ^ permalink raw reply [flat|nested] 7+ messages in thread
* 回复: [PATCH v2] tipc: Don't using smp_processor_id() in preemptible code 2020-07-14 14:15 ` Eric Dumazet @ 2020-07-15 2:12 ` Zhang, Qiang 2020-07-15 3:53 ` Tuong Tong Lien 0 siblings, 1 reply; 7+ messages in thread From: Zhang, Qiang @ 2020-07-15 2:12 UTC (permalink / raw) To: Eric Dumazet, jmaloy, davem, kuba, tuong.t.lien, Xue, Ying Cc: netdev, tipc-discussion, linux-kernel ________________________________________ 发件人: Eric Dumazet <eric.dumazet@gmail.com> 发送时间: 2020年7月14日 22:15 收件人: Zhang, Qiang; jmaloy@redhat.com; davem@davemloft.net; kuba@kernel.org; tuong.t.lien@dektech.com.au; eric.dumazet@gmail.com; Xue, Ying 抄送: netdev@vger.kernel.org; tipc-discussion@lists.sourceforge.net; linux-kernel@vger.kernel.org 主题: Re: [PATCH v2] tipc: Don't using smp_processor_id() in preemptible code On 7/14/20 1:05 AM, 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 > > Fixes: fc1b6d6de2208 ("tipc: introduce TIPC encryption & authentication") > Reported-by: syzbot+263f8c0d007dc09b2dda@syzkaller.appspotmail.com > Signed-off-by: Zhang Qiang <qiang.zhang@windriver.com> > --- > v1->v2: > add fixes tags. > > 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; > } > > > You have not explained why this was safe. > > This seems to hide a real bug. > > Presumably callers of this function should have disable preemption, and maybe > interrupts as well. > >Right after put_cpu_ptr(tfm_entry), this thread could migrate to another cpu, >and still access >data owned by the old cpu. Thanks for you suggest, I will check code again. ^ permalink raw reply [flat|nested] 7+ messages in thread
* RE: [PATCH v2] tipc: Don't using smp_processor_id() in preemptible code 2020-07-15 2:12 ` 回复: " Zhang, Qiang @ 2020-07-15 3:53 ` Tuong Tong Lien 2020-07-15 5:27 ` 回复: " Zhang, Qiang 0 siblings, 1 reply; 7+ messages in thread From: Tuong Tong Lien @ 2020-07-15 3:53 UTC (permalink / raw) To: Zhang, Qiang, Eric Dumazet, jmaloy, davem, kuba, Xue, Ying Cc: netdev, tipc-discussion, linux-kernel > -----Original Message----- > From: Zhang, Qiang <Qiang.Zhang@windriver.com> > Sent: Wednesday, July 15, 2020 9:13 AM > To: Eric Dumazet <eric.dumazet@gmail.com>; jmaloy@redhat.com; davem@davemloft.net; kuba@kernel.org; Tuong Tong Lien > <tuong.t.lien@dektech.com.au>; Xue, Ying <Ying.Xue@windriver.com> > Cc: netdev@vger.kernel.org; tipc-discussion@lists.sourceforge.net; linux-kernel@vger.kernel.org > Subject: 回复: [PATCH v2] tipc: Don't using smp_processor_id() in preemptible code > > > > ________________________________________ > 发件人: Eric Dumazet <eric.dumazet@gmail.com> > 发送时间: 2020年7月14日 22:15 > 收件人: Zhang, Qiang; jmaloy@redhat.com; davem@davemloft.net; kuba@kernel.org; tuong.t.lien@dektech.com.au; > eric.dumazet@gmail.com; Xue, Ying > 抄送: netdev@vger.kernel.org; tipc-discussion@lists.sourceforge.net; linux-kernel@vger.kernel.org > 主题: Re: [PATCH v2] tipc: Don't using smp_processor_id() in preemptible code > > > > On 7/14/20 1:05 AM, 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 > > > > Fixes: fc1b6d6de2208 ("tipc: introduce TIPC encryption & authentication") > > Reported-by: syzbot+263f8c0d007dc09b2dda@syzkaller.appspotmail.com > > Signed-off-by: Zhang Qiang <qiang.zhang@windriver.com> > > --- > > v1->v2: > > add fixes tags. > > > > 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; > > } > > > > > > > You have not explained why this was safe. > > > > This seems to hide a real bug. > > > > Presumably callers of this function should have disable preemption, and maybe > interrupts as well. > > > >Right after put_cpu_ptr(tfm_entry), this thread could migrate to another cpu, >and still access > >data owned by the old cpu. > > Thanks for you suggest, I will check code again. > Actually, last week I sent a similar patch to tipc-discussion which covers the case as well (there is also another place causing the same issue...). If you don't mind, you can take a look at below (just copied/pasted). BR/Tuong -----Original Message----- From: Tuong Tong Lien <tuong.t.lien@dektech.com.au> Sent: Friday, July 10, 2020 5:11 PM To: jmaloy@redhat.com; maloy@donjonn.com; ying.xue@windriver.com; tipc-discussion@lists.sourceforge.net Cc: tipc-dek <tipc-dek@dektech.com.au> Subject: [PATCH RFC 1/5] tipc: fix using smp_processor_id() in preemptible The 'this_cpu_ptr()' is used to obtain the AEAD key' TFM on the current CPU for encryption, however the execution can be preemptible since it's actually user-space context, so the 'using smp_processor_id() in preemptible' has been observed. We fix the issue by using the 'get/put_cpu_ptr()' API which consists of a 'preempt_disable()' instead. Signed-off-by: Tuong Lien <tuong.t.lien@dektech.com.au> --- net/tipc/crypto.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c index c8c47fc72653..1827ce4fac5d 100644 --- a/net/tipc/crypto.c +++ b/net/tipc/crypto.c @@ -326,7 +326,8 @@ static void tipc_aead_free(struct rcu_head *rp) if (aead->cloned) { tipc_aead_put(aead->cloned); } else { - head = *this_cpu_ptr(aead->tfm_entry); + head = *get_cpu_ptr(aead->tfm_entry); + put_cpu_ptr(aead->tfm_entry); list_for_each_entry_safe(tfm_entry, tmp, &head->list, list) { crypto_free_aead(tfm_entry->tfm); list_del(&tfm_entry->list); @@ -399,10 +400,15 @@ 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; + struct crypto_aead *tfm; + tfm_entry = get_cpu_ptr(aead->tfm_entry); *tfm_entry = list_next_entry(*tfm_entry, list); - return (*tfm_entry)->tfm; + tfm = (*tfm_entry)->tfm; + put_cpu_ptr(tfm_entry); + + return tfm; } /** -- 2.13.7 ^ permalink raw reply related [flat|nested] 7+ messages in thread
* 回复: [PATCH v2] tipc: Don't using smp_processor_id() in preemptible code 2020-07-15 3:53 ` Tuong Tong Lien @ 2020-07-15 5:27 ` Zhang, Qiang 2020-07-15 6:05 ` Zhang, Qiang 0 siblings, 1 reply; 7+ messages in thread From: Zhang, Qiang @ 2020-07-15 5:27 UTC (permalink / raw) To: Tuong Tong Lien, Eric Dumazet, jmaloy, davem, kuba, Xue, Ying Cc: netdev, tipc-discussion, linux-kernel ________________________________________ 发件人: Tuong Tong Lien <tuong.t.lien@dektech.com.au> 发送时间: 2020年7月15日 11:53 收件人: Zhang, Qiang; Eric Dumazet; jmaloy@redhat.com; davem@davemloft.net; kuba@kernel.org; Xue, Ying 抄送: netdev@vger.kernel.org; tipc-discussion@lists.sourceforge.net; linux-kernel@vger.kernel.org 主题: RE: [PATCH v2] tipc: Don't using smp_processor_id() in preemptible code > -----Original Message----- > From: Zhang, Qiang <Qiang.Zhang@windriver.com> > Sent: Wednesday, July 15, 2020 9:13 AM > To: Eric Dumazet <eric.dumazet@gmail.com>; jmaloy@redhat.com; davem@davemloft.net; kuba@kernel.org; Tuong Tong Lien > <tuong.t.lien@dektech.com.au>; Xue, Ying <Ying.Xue@windriver.com> > Cc: netdev@vger.kernel.org; tipc-discussion@lists.sourceforge.net; linux-kernel@vger.kernel.org > Subject: 回复: [PATCH v2] tipc: Don't using smp_processor_id() in preemptible code > > > > ________________________________________ > 发件人: Eric Dumazet <eric.dumazet@gmail.com> > 发送时间: 2020年7月14日 22:15 > 收件人: Zhang, Qiang; jmaloy@redhat.com; davem@davemloft.net; kuba@kernel.org; tuong.t.lien@dektech.com.au; > eric.dumazet@gmail.com; Xue, Ying > 抄送: netdev@vger.kernel.org; tipc-discussion@lists.sourceforge.net; linux-kernel@vger.kernel.org > 主题: Re: [PATCH v2] tipc: Don't using smp_processor_id() in preemptible code > > > > On 7/14/20 1:05 AM, 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 > > > > Fixes: fc1b6d6de2208 ("tipc: introduce TIPC encryption & authentication") > > Reported-by: syzbot+263f8c0d007dc09b2dda@syzkaller.appspotmail.com > > Signed-off-by: Zhang Qiang <qiang.zhang@windriver.com> > > --- > > v1->v2: > > add fixes tags. > > > > 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; > > } > > > > > > > You have not explained why this was safe. > > > > This seems to hide a real bug. > > > > Presumably callers of this function should have disable preemption, and maybe > interrupts as well. > > > >Right after put_cpu_ptr(tfm_entry), this thread could migrate to another cpu, >and still access > >data owned by the old cpu. > > Thanks for you suggest, I will check code again. > >Actually, last week I sent a similar patch to tipc-discussion which covers the >case as well (there is also another place causing the same issue...). If you >don't mind, you can take a look at below (just copied/pasted). >BR/Tuong Hi Tuong Tong Lien The tipc_aead_free is RCU callback, this func is called in softirq context which preemption has been banned so should not add preempt_disable/enable. thanks Zhang Qiang >-----Original Message----- >From: Tuong Tong Lien <tuong.t.lien@dektech.com.au> >Sent: Friday, July 10, 2020 5:11 PM >To: jmaloy@redhat.com; maloy@donjonn.com; ying.xue@windriver.com; tipc-discussion@lists.sourceforge.net >Cc: tipc-dek <tipc-dek@dektech.com.au> Subject: [PATCH RFC 1/5] tipc: fix using smp_processor_id() in preemptible > >The 'this_cpu_ptr()' is used to obtain the AEAD key' TFM on the current CPU for encryption, however the execution can be preemptible since it's actually user-space context, so the 'using smp_processor_id() in preemptible' has been observed. We fix the issue by using the 'get/put_cpu_ptr()' API which consists of a 'preempt_disable()' instead. Signed-off-by: Tuong Lien <tuong.t.lien@dektech.com.au> --- net/tipc/crypto.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c index c8c47fc72653..1827ce4fac5d 100644 --- a/net/tipc/crypto.c +++ b/net/tipc/crypto.c @@ -326,7 +326,8 @@ static void tipc_aead_free(struct rcu_head *rp) if (aead->cloned) { tipc_aead_put(aead->cloned); } else { - head = *this_cpu_ptr(aead->tfm_entry); + head = *get_cpu_ptr(aead->tfm_entry); + put_cpu_ptr(aead->tfm_entry); list_for_each_entry_safe(tfm_entry, tmp, &head->list, list) { crypto_free_aead(tfm_entry->tfm); list_del(&tfm_entry->list); @@ -399,10 +400,15 @@ 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; + struct crypto_aead *tfm; + tfm_entry = get_cpu_ptr(aead->tfm_entry); *tfm_entry = list_next_entry(*tfm_entry, list); - return (*tfm_entry)->tfm; + tfm = (*tfm_entry)->tfm; + put_cpu_ptr(tfm_entry); + + return tfm; } /** -- 2.13.7 ^ permalink raw reply related [flat|nested] 7+ messages in thread
* 回复: [PATCH v2] tipc: Don't using smp_processor_id() in preemptible code 2020-07-15 5:27 ` 回复: " Zhang, Qiang @ 2020-07-15 6:05 ` Zhang, Qiang 0 siblings, 0 replies; 7+ messages in thread From: Zhang, Qiang @ 2020-07-15 6:05 UTC (permalink / raw) To: Tuong Tong Lien, Eric Dumazet, jmaloy, davem, kuba, Xue, Ying Cc: netdev, tipc-discussion, linux-kernel ________________________________________ 发件人: Zhang, Qiang <Qiang.Zhang@windriver.com> 发送时间: 2020年7月15日 13:27 收件人: Tuong Tong Lien; Eric Dumazet; jmaloy@redhat.com; davem@davemloft.net; kuba@kernel.org; Xue, Ying 抄送: netdev@vger.kernel.org; tipc-discussion@lists.sourceforge.net; linux-kernel@vger.kernel.org 主题: 回复: [PATCH v2] tipc: Don't using smp_processor_id() in preemptible code ________________________________________ 发件人: Tuong Tong Lien <tuong.t.lien@dektech.com.au> 发送时间: 2020年7月15日 11:53 收件人: Zhang, Qiang; Eric Dumazet; jmaloy@redhat.com; davem@davemloft.net; kuba@kernel.org; Xue, Ying 抄送: netdev@vger.kernel.org; tipc-discussion@lists.sourceforge.net; linux-kernel@vger.kernel.org 主题: RE: [PATCH v2] tipc: Don't using smp_processor_id() in preemptible code > -----Original Message----- > From: Zhang, Qiang <Qiang.Zhang@windriver.com> > Sent: Wednesday, July 15, 2020 9:13 AM > To: Eric Dumazet <eric.dumazet@gmail.com>; jmaloy@redhat.com; davem@davemloft.net; kuba@kernel.org; Tuong Tong Lien > <tuong.t.lien@dektech.com.au>; Xue, Ying <Ying.Xue@windriver.com> > Cc: netdev@vger.kernel.org; tipc-discussion@lists.sourceforge.net; linux-kernel@vger.kernel.org > Subject: 回复: [PATCH v2] tipc: Don't using smp_processor_id() in preemptible code > > > > ________________________________________ > 发件人: Eric Dumazet <eric.dumazet@gmail.com> > 发送时间: 2020年7月14日 22:15 > 收件人: Zhang, Qiang; jmaloy@redhat.com; davem@davemloft.net; kuba@kernel.org; tuong.t.lien@dektech.com.au; > eric.dumazet@gmail.com; Xue, Ying > 抄送: netdev@vger.kernel.org; tipc-discussion@lists.sourceforge.net; linux-kernel@vger.kernel.org > 主题: Re: [PATCH v2] tipc: Don't using smp_processor_id() in preemptible code > > > > On 7/14/20 1:05 AM, 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 > > > > Fixes: fc1b6d6de2208 ("tipc: introduce TIPC encryption & authentication") > > Reported-by: syzbot+263f8c0d007dc09b2dda@syzkaller.appspotmail.com > > Signed-off-by: Zhang Qiang <qiang.zhang@windriver.com> > > --- > > v1->v2: > > add fixes tags. > > > > 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; > > } > > > > > > > You have not explained why this was safe. > > > > This seems to hide a real bug. > > > > Presumably callers of this function should have disable preemption, and maybe > interrupts as well. > > > >Right after put_cpu_ptr(tfm_entry), this thread could migrate to another cpu, >and still access > >data owned by the old cpu. > > Thanks for you suggest, I will check code again. > >Actually, last week I sent a similar patch to tipc-discussion which covers the >case as well (there is also another place causing the same issue...). If you >don't mind, you can take a look at below (just copied/pasted). >BR/Tuong >Hi Tuong Tong Lien >The tipc_aead_free is RCU callback, this func is called in softirq context which >preemption has been banned >so should not add preempt_disable/enable. >thanks >Zhang Qiang sorry there are some questions in my reply. the tipc_aead_free function may also be called in the thread context. if enable CONFIG_RCU_BOOST >-----Original Message----- >From: Tuong Tong Lien <tuong.t.lien@dektech.com.au> >Sent: Friday, July 10, 2020 5:11 PM >To: jmaloy@redhat.com; maloy@donjonn.com; ying.xue@windriver.com; tipc-discussion@lists.sourceforge.net >Cc: tipc-dek <tipc-dek@dektech.com.au> Subject: [PATCH RFC 1/5] tipc: fix using smp_processor_id() in preemptible > >The 'this_cpu_ptr()' is used to obtain the AEAD key' TFM on the current CPU for encryption, however the execution can be preemptible since it's actually user-space context, so the 'using smp_processor_id() in preemptible' has been observed. We fix the issue by using the 'get/put_cpu_ptr()' API which consists of a 'preempt_disable()' instead. Signed-off-by: Tuong Lien <tuong.t.lien@dektech.com.au> --- net/tipc/crypto.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c index c8c47fc72653..1827ce4fac5d 100644 --- a/net/tipc/crypto.c +++ b/net/tipc/crypto.c @@ -326,7 +326,8 @@ static void tipc_aead_free(struct rcu_head *rp) if (aead->cloned) { tipc_aead_put(aead->cloned); } else { - head = *this_cpu_ptr(aead->tfm_entry); + head = *get_cpu_ptr(aead->tfm_entry); + put_cpu_ptr(aead->tfm_entry); list_for_each_entry_safe(tfm_entry, tmp, &head->list, list) { crypto_free_aead(tfm_entry->tfm); list_del(&tfm_entry->list); @@ -399,10 +400,15 @@ 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; + struct crypto_aead *tfm; + tfm_entry = get_cpu_ptr(aead->tfm_entry); *tfm_entry = list_next_entry(*tfm_entry, list); - return (*tfm_entry)->tfm; + tfm = (*tfm_entry)->tfm; + put_cpu_ptr(tfm_entry); + + return tfm; } /** -- 2.13.7 ^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH v2] tipc: Don't using smp_processor_id() in preemptible code @ 2020-07-15 18:43 Markus Elfring 0 siblings, 0 replies; 7+ messages in thread From: Markus Elfring @ 2020-07-15 18:43 UTC (permalink / raw) To: Zhang Qiang, netdev, tipc-discussion Cc: linux-kernel, David S. Miller, Eric Dumazet, Jakub Kicinski, Jon Maloy, Tuong Lien, Ying Xue * I find the patch subject improvable. * Please add a change description for the desired commit. Regards, Markus ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2020-07-15 18:44 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2020-07-14 8:05 [PATCH v2] tipc: Don't using smp_processor_id() in preemptible code qiang.zhang 2020-07-14 14:15 ` Eric Dumazet 2020-07-15 2:12 ` 回复: " Zhang, Qiang 2020-07-15 3:53 ` Tuong Tong Lien 2020-07-15 5:27 ` 回复: " Zhang, Qiang 2020-07-15 6:05 ` Zhang, Qiang 2020-07-15 18:43 Markus Elfring
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