* [PATCH v1 bpf] tcp_bpf: Call sk_msg_free() when tcp_bpf_send_verdict() fails to allocate psock->cork.
@ 2025-09-09 23:26 Kuniyuki Iwashima
2025-09-10 5:15 ` Martin KaFai Lau
2025-09-10 14:10 ` patchwork-bot+netdevbpf
0 siblings, 2 replies; 6+ messages in thread
From: Kuniyuki Iwashima @ 2025-09-09 23:26 UTC (permalink / raw)
To: John Fastabend, Jakub Sitnicki, Alexei Starovoitov,
Daniel Borkmann
Cc: Kuniyuki Iwashima, Kuniyuki Iwashima, netdev, bpf,
syzbot+4cabd1d2fa917a456db8
syzbot reported the splat below. [0]
The repro does the following:
1. Load a sk_msg prog that calls bpf_msg_cork_bytes(msg, cork_bytes)
2. Attach the prog to a SOCKMAP
3. Add a socket to the SOCKMAP
4. Activate fault injection
5. Send data less than cork_bytes
At 5., the data is carried over to the next sendmsg() as it is
smaller than the cork_bytes specified by bpf_msg_cork_bytes().
Then, tcp_bpf_send_verdict() tries to allocate psock->cork to hold
the data, but this fails silently due to fault injection + __GFP_NOWARN.
If the allocation fails, we need to revert the sk->sk_forward_alloc
change done by sk_msg_alloc().
Let's call sk_msg_free() when tcp_bpf_send_verdict fails to allocate
psock->cork.
[0]:
WARNING: net/ipv4/af_inet.c:156 at inet_sock_destruct+0x623/0x730 net/ipv4/af_inet.c:156, CPU#1: syz-executor/5983
Modules linked in:
CPU: 1 UID: 0 PID: 5983 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:inet_sock_destruct+0x623/0x730 net/ipv4/af_inet.c:156
Code: 0f 0b 90 e9 62 fe ff ff e8 7a db b5 f7 90 0f 0b 90 e9 95 fe ff ff e8 6c db b5 f7 90 0f 0b 90 e9 bb fe ff ff e8 5e db b5 f7 90 <0f> 0b 90 e9 e1 fe ff ff 89 f9 80 e1 07 80 c1 03 38 c1 0f 8c 9f fc
RSP: 0018:ffffc90000a08b48 EFLAGS: 00010246
RAX: ffffffff8a09d0b2 RBX: dffffc0000000000 RCX: ffff888024a23c80
RDX: 0000000000000100 RSI: 0000000000000fff RDI: 0000000000000000
RBP: 0000000000000fff R08: ffff88807e07c627 R09: 1ffff1100fc0f8c4
R10: dffffc0000000000 R11: ffffed100fc0f8c5 R12: ffff88807e07c380
R13: dffffc0000000000 R14: ffff88807e07c60c R15: 1ffff1100fc0f872
FS: 00005555604c4500(0000) GS:ffff888125af1000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555604df5c8 CR3: 0000000032b06000 CR4: 00000000003526f0
Call Trace:
<IRQ>
__sk_destruct+0x86/0x660 net/core/sock.c:2339
rcu_do_batch kernel/rcu/tree.c:2605 [inline]
rcu_core+0xca8/0x1770 kernel/rcu/tree.c:2861
handle_softirqs+0x286/0x870 kernel/softirq.c:579
__do_softirq kernel/softirq.c:613 [inline]
invoke_softirq kernel/softirq.c:453 [inline]
__irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680
irq_exit_rcu+0x9/0x30 kernel/softirq.c:696
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1052
</IRQ>
Fixes: 4f738adba30a ("bpf: create tcp_bpf_ulp allowing BPF to monitor socket TX/RX data")
Reported-by: syzbot+4cabd1d2fa917a456db8@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/68c0b6b5.050a0220.3c6139.0013.GAE@google.com/
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
---
net/ipv4/tcp_bpf.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index ba581785adb4..ee6a371e65a4 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -408,8 +408,10 @@ static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock,
if (!psock->cork) {
psock->cork = kzalloc(sizeof(*psock->cork),
GFP_ATOMIC | __GFP_NOWARN);
- if (!psock->cork)
+ if (!psock->cork) {
+ sk_msg_free(sk, msg);
return -ENOMEM;
+ }
}
memcpy(psock->cork, msg, sizeof(*msg));
return 0;
--
2.51.0.384.g4c02a37b29-goog
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v1 bpf] tcp_bpf: Call sk_msg_free() when tcp_bpf_send_verdict() fails to allocate psock->cork.
2025-09-09 23:26 [PATCH v1 bpf] tcp_bpf: Call sk_msg_free() when tcp_bpf_send_verdict() fails to allocate psock->cork Kuniyuki Iwashima
@ 2025-09-10 5:15 ` Martin KaFai Lau
2025-09-10 6:56 ` Kuniyuki Iwashima
2025-09-10 14:10 ` patchwork-bot+netdevbpf
1 sibling, 1 reply; 6+ messages in thread
From: Martin KaFai Lau @ 2025-09-10 5:15 UTC (permalink / raw)
To: Kuniyuki Iwashima
Cc: John Fastabend, Jakub Sitnicki, Alexei Starovoitov,
Daniel Borkmann, Kuniyuki Iwashima, netdev, bpf,
syzbot+4cabd1d2fa917a456db8
On 9/9/25 4:26 PM, Kuniyuki Iwashima wrote:
> syzbot reported the splat below. [0]
>
> The repro does the following:
>
> 1. Load a sk_msg prog that calls bpf_msg_cork_bytes(msg, cork_bytes)
> 2. Attach the prog to a SOCKMAP
> 3. Add a socket to the SOCKMAP
> 4. Activate fault injection
> 5. Send data less than cork_bytes
>
> At 5., the data is carried over to the next sendmsg() as it is
> smaller than the cork_bytes specified by bpf_msg_cork_bytes().
>
> Then, tcp_bpf_send_verdict() tries to allocate psock->cork to hold
> the data, but this fails silently due to fault injection + __GFP_NOWARN.
>
> If the allocation fails, we need to revert the sk->sk_forward_alloc
> change done by sk_msg_alloc().
>
> Let's call sk_msg_free() when tcp_bpf_send_verdict fails to allocate
> psock->cork.
>
> [0]:
> WARNING: net/ipv4/af_inet.c:156 at inet_sock_destruct+0x623/0x730 net/ipv4/af_inet.c:156, CPU#1: syz-executor/5983
> Modules linked in:
> CPU: 1 UID: 0 PID: 5983 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full)
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
> RIP: 0010:inet_sock_destruct+0x623/0x730 net/ipv4/af_inet.c:156
> Code: 0f 0b 90 e9 62 fe ff ff e8 7a db b5 f7 90 0f 0b 90 e9 95 fe ff ff e8 6c db b5 f7 90 0f 0b 90 e9 bb fe ff ff e8 5e db b5 f7 90 <0f> 0b 90 e9 e1 fe ff ff 89 f9 80 e1 07 80 c1 03 38 c1 0f 8c 9f fc
> RSP: 0018:ffffc90000a08b48 EFLAGS: 00010246
> RAX: ffffffff8a09d0b2 RBX: dffffc0000000000 RCX: ffff888024a23c80
> RDX: 0000000000000100 RSI: 0000000000000fff RDI: 0000000000000000
> RBP: 0000000000000fff R08: ffff88807e07c627 R09: 1ffff1100fc0f8c4
> R10: dffffc0000000000 R11: ffffed100fc0f8c5 R12: ffff88807e07c380
> R13: dffffc0000000000 R14: ffff88807e07c60c R15: 1ffff1100fc0f872
> FS: 00005555604c4500(0000) GS:ffff888125af1000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00005555604df5c8 CR3: 0000000032b06000 CR4: 00000000003526f0
> Call Trace:
> <IRQ>
> __sk_destruct+0x86/0x660 net/core/sock.c:2339
> rcu_do_batch kernel/rcu/tree.c:2605 [inline]
> rcu_core+0xca8/0x1770 kernel/rcu/tree.c:2861
> handle_softirqs+0x286/0x870 kernel/softirq.c:579
> __do_softirq kernel/softirq.c:613 [inline]
> invoke_softirq kernel/softirq.c:453 [inline]
> __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680
> irq_exit_rcu+0x9/0x30 kernel/softirq.c:696
> instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
> sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1052
> </IRQ>
>
> Fixes: 4f738adba30a ("bpf: create tcp_bpf_ulp allowing BPF to monitor socket TX/RX data")
> Reported-by: syzbot+4cabd1d2fa917a456db8@syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/netdev/68c0b6b5.050a0220.3c6139.0013.GAE@google.com/
> Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
> ---
> net/ipv4/tcp_bpf.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
> index ba581785adb4..ee6a371e65a4 100644
> --- a/net/ipv4/tcp_bpf.c
> +++ b/net/ipv4/tcp_bpf.c
> @@ -408,8 +408,10 @@ static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock,
> if (!psock->cork) {
> psock->cork = kzalloc(sizeof(*psock->cork),
> GFP_ATOMIC | __GFP_NOWARN);
> - if (!psock->cork)
> + if (!psock->cork) {
> + sk_msg_free(sk, msg);
Nothing has been corked yet, does it need to update the "*copied":
*copied -= sk_msg_free(sk, msg);
> return -ENOMEM;
> + }
> }
> memcpy(psock->cork, msg, sizeof(*msg));
> return 0;
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v1 bpf] tcp_bpf: Call sk_msg_free() when tcp_bpf_send_verdict() fails to allocate psock->cork.
2025-09-10 5:15 ` Martin KaFai Lau
@ 2025-09-10 6:56 ` Kuniyuki Iwashima
2025-09-10 14:05 ` Martin KaFai Lau
0 siblings, 1 reply; 6+ messages in thread
From: Kuniyuki Iwashima @ 2025-09-10 6:56 UTC (permalink / raw)
To: Martin KaFai Lau
Cc: John Fastabend, Jakub Sitnicki, Alexei Starovoitov,
Daniel Borkmann, Kuniyuki Iwashima, netdev, bpf,
syzbot+4cabd1d2fa917a456db8
On Tue, Sep 9, 2025 at 10:15 PM Martin KaFai Lau <martin.lau@linux.dev> wrote:
>
> On 9/9/25 4:26 PM, Kuniyuki Iwashima wrote:
> > syzbot reported the splat below. [0]
> >
> > The repro does the following:
> >
> > 1. Load a sk_msg prog that calls bpf_msg_cork_bytes(msg, cork_bytes)
> > 2. Attach the prog to a SOCKMAP
> > 3. Add a socket to the SOCKMAP
> > 4. Activate fault injection
> > 5. Send data less than cork_bytes
> >
> > At 5., the data is carried over to the next sendmsg() as it is
> > smaller than the cork_bytes specified by bpf_msg_cork_bytes().
> >
> > Then, tcp_bpf_send_verdict() tries to allocate psock->cork to hold
> > the data, but this fails silently due to fault injection + __GFP_NOWARN.
> >
> > If the allocation fails, we need to revert the sk->sk_forward_alloc
> > change done by sk_msg_alloc().
> >
> > Let's call sk_msg_free() when tcp_bpf_send_verdict fails to allocate
> > psock->cork.
> >
> > [0]:
> > WARNING: net/ipv4/af_inet.c:156 at inet_sock_destruct+0x623/0x730 net/ipv4/af_inet.c:156, CPU#1: syz-executor/5983
> > Modules linked in:
> > CPU: 1 UID: 0 PID: 5983 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full)
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
> > RIP: 0010:inet_sock_destruct+0x623/0x730 net/ipv4/af_inet.c:156
> > Code: 0f 0b 90 e9 62 fe ff ff e8 7a db b5 f7 90 0f 0b 90 e9 95 fe ff ff e8 6c db b5 f7 90 0f 0b 90 e9 bb fe ff ff e8 5e db b5 f7 90 <0f> 0b 90 e9 e1 fe ff ff 89 f9 80 e1 07 80 c1 03 38 c1 0f 8c 9f fc
> > RSP: 0018:ffffc90000a08b48 EFLAGS: 00010246
> > RAX: ffffffff8a09d0b2 RBX: dffffc0000000000 RCX: ffff888024a23c80
> > RDX: 0000000000000100 RSI: 0000000000000fff RDI: 0000000000000000
> > RBP: 0000000000000fff R08: ffff88807e07c627 R09: 1ffff1100fc0f8c4
> > R10: dffffc0000000000 R11: ffffed100fc0f8c5 R12: ffff88807e07c380
> > R13: dffffc0000000000 R14: ffff88807e07c60c R15: 1ffff1100fc0f872
> > FS: 00005555604c4500(0000) GS:ffff888125af1000(0000) knlGS:0000000000000000
> > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 00005555604df5c8 CR3: 0000000032b06000 CR4: 00000000003526f0
> > Call Trace:
> > <IRQ>
> > __sk_destruct+0x86/0x660 net/core/sock.c:2339
> > rcu_do_batch kernel/rcu/tree.c:2605 [inline]
> > rcu_core+0xca8/0x1770 kernel/rcu/tree.c:2861
> > handle_softirqs+0x286/0x870 kernel/softirq.c:579
> > __do_softirq kernel/softirq.c:613 [inline]
> > invoke_softirq kernel/softirq.c:453 [inline]
> > __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680
> > irq_exit_rcu+0x9/0x30 kernel/softirq.c:696
> > instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
> > sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1052
> > </IRQ>
> >
> > Fixes: 4f738adba30a ("bpf: create tcp_bpf_ulp allowing BPF to monitor socket TX/RX data")
> > Reported-by: syzbot+4cabd1d2fa917a456db8@syzkaller.appspotmail.com
> > Closes: https://lore.kernel.org/netdev/68c0b6b5.050a0220.3c6139.0013.GAE@google.com/
> > Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
> > ---
> > net/ipv4/tcp_bpf.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
> > index ba581785adb4..ee6a371e65a4 100644
> > --- a/net/ipv4/tcp_bpf.c
> > +++ b/net/ipv4/tcp_bpf.c
> > @@ -408,8 +408,10 @@ static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock,
> > if (!psock->cork) {
> > psock->cork = kzalloc(sizeof(*psock->cork),
> > GFP_ATOMIC | __GFP_NOWARN);
> > - if (!psock->cork)
> > + if (!psock->cork) {
> > + sk_msg_free(sk, msg);
>
> Nothing has been corked yet, does it need to update the "*copied":
>
> *copied -= sk_msg_free(sk, msg);
Oh exactly, or simply *copied = 0 ?
>
>
> > return -ENOMEM;
> > + }
> > }
> > memcpy(psock->cork, msg, sizeof(*msg));
> > return 0;
>
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v1 bpf] tcp_bpf: Call sk_msg_free() when tcp_bpf_send_verdict() fails to allocate psock->cork.
2025-09-10 6:56 ` Kuniyuki Iwashima
@ 2025-09-10 14:05 ` Martin KaFai Lau
2025-09-10 15:59 ` Kuniyuki Iwashima
0 siblings, 1 reply; 6+ messages in thread
From: Martin KaFai Lau @ 2025-09-10 14:05 UTC (permalink / raw)
To: Kuniyuki Iwashima
Cc: John Fastabend, Jakub Sitnicki, Alexei Starovoitov,
Daniel Borkmann, Kuniyuki Iwashima, netdev, bpf,
syzbot+4cabd1d2fa917a456db8
On 9/9/25 11:56 PM, Kuniyuki Iwashima wrote:
> On Tue, Sep 9, 2025 at 10:15 PM Martin KaFai Lau <martin.lau@linux.dev> wrote:
>>
>> On 9/9/25 4:26 PM, Kuniyuki Iwashima wrote:
>>> syzbot reported the splat below. [0]
>>>
>>> The repro does the following:
>>>
>>> 1. Load a sk_msg prog that calls bpf_msg_cork_bytes(msg, cork_bytes)
>>> 2. Attach the prog to a SOCKMAP
>>> 3. Add a socket to the SOCKMAP
>>> 4. Activate fault injection
>>> 5. Send data less than cork_bytes
>>>
>>> At 5., the data is carried over to the next sendmsg() as it is
>>> smaller than the cork_bytes specified by bpf_msg_cork_bytes().
>>>
>>> Then, tcp_bpf_send_verdict() tries to allocate psock->cork to hold
>>> the data, but this fails silently due to fault injection + __GFP_NOWARN.
>>>
>>> If the allocation fails, we need to revert the sk->sk_forward_alloc
>>> change done by sk_msg_alloc().
>>>
>>> Let's call sk_msg_free() when tcp_bpf_send_verdict fails to allocate
>>> psock->cork.
>>>
>>> [0]:
>>> WARNING: net/ipv4/af_inet.c:156 at inet_sock_destruct+0x623/0x730 net/ipv4/af_inet.c:156, CPU#1: syz-executor/5983
>>> Modules linked in:
>>> CPU: 1 UID: 0 PID: 5983 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full)
>>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
>>> RIP: 0010:inet_sock_destruct+0x623/0x730 net/ipv4/af_inet.c:156
>>> Code: 0f 0b 90 e9 62 fe ff ff e8 7a db b5 f7 90 0f 0b 90 e9 95 fe ff ff e8 6c db b5 f7 90 0f 0b 90 e9 bb fe ff ff e8 5e db b5 f7 90 <0f> 0b 90 e9 e1 fe ff ff 89 f9 80 e1 07 80 c1 03 38 c1 0f 8c 9f fc
>>> RSP: 0018:ffffc90000a08b48 EFLAGS: 00010246
>>> RAX: ffffffff8a09d0b2 RBX: dffffc0000000000 RCX: ffff888024a23c80
>>> RDX: 0000000000000100 RSI: 0000000000000fff RDI: 0000000000000000
>>> RBP: 0000000000000fff R08: ffff88807e07c627 R09: 1ffff1100fc0f8c4
>>> R10: dffffc0000000000 R11: ffffed100fc0f8c5 R12: ffff88807e07c380
>>> R13: dffffc0000000000 R14: ffff88807e07c60c R15: 1ffff1100fc0f872
>>> FS: 00005555604c4500(0000) GS:ffff888125af1000(0000) knlGS:0000000000000000
>>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> CR2: 00005555604df5c8 CR3: 0000000032b06000 CR4: 00000000003526f0
>>> Call Trace:
>>> <IRQ>
>>> __sk_destruct+0x86/0x660 net/core/sock.c:2339
>>> rcu_do_batch kernel/rcu/tree.c:2605 [inline]
>>> rcu_core+0xca8/0x1770 kernel/rcu/tree.c:2861
>>> handle_softirqs+0x286/0x870 kernel/softirq.c:579
>>> __do_softirq kernel/softirq.c:613 [inline]
>>> invoke_softirq kernel/softirq.c:453 [inline]
>>> __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680
>>> irq_exit_rcu+0x9/0x30 kernel/softirq.c:696
>>> instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
>>> sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1052
>>> </IRQ>
>>>
>>> Fixes: 4f738adba30a ("bpf: create tcp_bpf_ulp allowing BPF to monitor socket TX/RX data")
>>> Reported-by: syzbot+4cabd1d2fa917a456db8@syzkaller.appspotmail.com
>>> Closes: https://lore.kernel.org/netdev/68c0b6b5.050a0220.3c6139.0013.GAE@google.com/
>>> Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
>>> ---
>>> net/ipv4/tcp_bpf.c | 4 +++-
>>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
>>> index ba581785adb4..ee6a371e65a4 100644
>>> --- a/net/ipv4/tcp_bpf.c
>>> +++ b/net/ipv4/tcp_bpf.c
>>> @@ -408,8 +408,10 @@ static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock,
>>> if (!psock->cork) {
>>> psock->cork = kzalloc(sizeof(*psock->cork),
>>> GFP_ATOMIC | __GFP_NOWARN);
>>> - if (!psock->cork)
>>> + if (!psock->cork) {
>>> + sk_msg_free(sk, msg);
>>
>> Nothing has been corked yet, does it need to update the "*copied":
>>
>> *copied -= sk_msg_free(sk, msg);
>
> Oh exactly, or simply *copied = 0 ?
Make sense. I made the change and updated the commit message for this fix also.
Applied. Thanks.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v1 bpf] tcp_bpf: Call sk_msg_free() when tcp_bpf_send_verdict() fails to allocate psock->cork.
2025-09-09 23:26 [PATCH v1 bpf] tcp_bpf: Call sk_msg_free() when tcp_bpf_send_verdict() fails to allocate psock->cork Kuniyuki Iwashima
2025-09-10 5:15 ` Martin KaFai Lau
@ 2025-09-10 14:10 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 6+ messages in thread
From: patchwork-bot+netdevbpf @ 2025-09-10 14:10 UTC (permalink / raw)
To: Kuniyuki Iwashima
Cc: john.fastabend, jakub, ast, daniel, kuni1840, netdev, bpf,
syzbot+4cabd1d2fa917a456db8
Hello:
This patch was applied to bpf/bpf.git (master)
by Martin KaFai Lau <martin.lau@kernel.org>:
On Tue, 9 Sep 2025 23:26:12 +0000 you wrote:
> syzbot reported the splat below. [0]
>
> The repro does the following:
>
> 1. Load a sk_msg prog that calls bpf_msg_cork_bytes(msg, cork_bytes)
> 2. Attach the prog to a SOCKMAP
> 3. Add a socket to the SOCKMAP
> 4. Activate fault injection
> 5. Send data less than cork_bytes
>
> [...]
Here is the summary with links:
- [v1,bpf] tcp_bpf: Call sk_msg_free() when tcp_bpf_send_verdict() fails to allocate psock->cork.
https://git.kernel.org/bpf/bpf/c/a3967baad4d5
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v1 bpf] tcp_bpf: Call sk_msg_free() when tcp_bpf_send_verdict() fails to allocate psock->cork.
2025-09-10 14:05 ` Martin KaFai Lau
@ 2025-09-10 15:59 ` Kuniyuki Iwashima
0 siblings, 0 replies; 6+ messages in thread
From: Kuniyuki Iwashima @ 2025-09-10 15:59 UTC (permalink / raw)
To: Martin KaFai Lau
Cc: John Fastabend, Jakub Sitnicki, Alexei Starovoitov,
Daniel Borkmann, Kuniyuki Iwashima, netdev, bpf,
syzbot+4cabd1d2fa917a456db8
On Wed, Sep 10, 2025 at 7:05 AM Martin KaFai Lau <martin.lau@linux.dev> wrote:
>
> On 9/9/25 11:56 PM, Kuniyuki Iwashima wrote:
> > On Tue, Sep 9, 2025 at 10:15 PM Martin KaFai Lau <martin.lau@linux.dev> wrote:
> >>
> >> On 9/9/25 4:26 PM, Kuniyuki Iwashima wrote:
> >>> syzbot reported the splat below. [0]
> >>>
> >>> The repro does the following:
> >>>
> >>> 1. Load a sk_msg prog that calls bpf_msg_cork_bytes(msg, cork_bytes)
> >>> 2. Attach the prog to a SOCKMAP
> >>> 3. Add a socket to the SOCKMAP
> >>> 4. Activate fault injection
> >>> 5. Send data less than cork_bytes
> >>>
> >>> At 5., the data is carried over to the next sendmsg() as it is
> >>> smaller than the cork_bytes specified by bpf_msg_cork_bytes().
> >>>
> >>> Then, tcp_bpf_send_verdict() tries to allocate psock->cork to hold
> >>> the data, but this fails silently due to fault injection + __GFP_NOWARN.
> >>>
> >>> If the allocation fails, we need to revert the sk->sk_forward_alloc
> >>> change done by sk_msg_alloc().
> >>>
> >>> Let's call sk_msg_free() when tcp_bpf_send_verdict fails to allocate
> >>> psock->cork.
> >>>
> >>> [0]:
> >>> WARNING: net/ipv4/af_inet.c:156 at inet_sock_destruct+0x623/0x730 net/ipv4/af_inet.c:156, CPU#1: syz-executor/5983
> >>> Modules linked in:
> >>> CPU: 1 UID: 0 PID: 5983 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full)
> >>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
> >>> RIP: 0010:inet_sock_destruct+0x623/0x730 net/ipv4/af_inet.c:156
> >>> Code: 0f 0b 90 e9 62 fe ff ff e8 7a db b5 f7 90 0f 0b 90 e9 95 fe ff ff e8 6c db b5 f7 90 0f 0b 90 e9 bb fe ff ff e8 5e db b5 f7 90 <0f> 0b 90 e9 e1 fe ff ff 89 f9 80 e1 07 80 c1 03 38 c1 0f 8c 9f fc
> >>> RSP: 0018:ffffc90000a08b48 EFLAGS: 00010246
> >>> RAX: ffffffff8a09d0b2 RBX: dffffc0000000000 RCX: ffff888024a23c80
> >>> RDX: 0000000000000100 RSI: 0000000000000fff RDI: 0000000000000000
> >>> RBP: 0000000000000fff R08: ffff88807e07c627 R09: 1ffff1100fc0f8c4
> >>> R10: dffffc0000000000 R11: ffffed100fc0f8c5 R12: ffff88807e07c380
> >>> R13: dffffc0000000000 R14: ffff88807e07c60c R15: 1ffff1100fc0f872
> >>> FS: 00005555604c4500(0000) GS:ffff888125af1000(0000) knlGS:0000000000000000
> >>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> >>> CR2: 00005555604df5c8 CR3: 0000000032b06000 CR4: 00000000003526f0
> >>> Call Trace:
> >>> <IRQ>
> >>> __sk_destruct+0x86/0x660 net/core/sock.c:2339
> >>> rcu_do_batch kernel/rcu/tree.c:2605 [inline]
> >>> rcu_core+0xca8/0x1770 kernel/rcu/tree.c:2861
> >>> handle_softirqs+0x286/0x870 kernel/softirq.c:579
> >>> __do_softirq kernel/softirq.c:613 [inline]
> >>> invoke_softirq kernel/softirq.c:453 [inline]
> >>> __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680
> >>> irq_exit_rcu+0x9/0x30 kernel/softirq.c:696
> >>> instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
> >>> sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1052
> >>> </IRQ>
> >>>
> >>> Fixes: 4f738adba30a ("bpf: create tcp_bpf_ulp allowing BPF to monitor socket TX/RX data")
> >>> Reported-by: syzbot+4cabd1d2fa917a456db8@syzkaller.appspotmail.com
> >>> Closes: https://lore.kernel.org/netdev/68c0b6b5.050a0220.3c6139.0013.GAE@google.com/
> >>> Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
> >>> ---
> >>> net/ipv4/tcp_bpf.c | 4 +++-
> >>> 1 file changed, 3 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
> >>> index ba581785adb4..ee6a371e65a4 100644
> >>> --- a/net/ipv4/tcp_bpf.c
> >>> +++ b/net/ipv4/tcp_bpf.c
> >>> @@ -408,8 +408,10 @@ static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock,
> >>> if (!psock->cork) {
> >>> psock->cork = kzalloc(sizeof(*psock->cork),
> >>> GFP_ATOMIC | __GFP_NOWARN);
> >>> - if (!psock->cork)
> >>> + if (!psock->cork) {
> >>> + sk_msg_free(sk, msg);
> >>
> >> Nothing has been corked yet, does it need to update the "*copied":
> >>
> >> *copied -= sk_msg_free(sk, msg);
> >
> > Oh exactly, or simply *copied = 0 ?
>
> Make sense. I made the change and updated the commit message for this fix also.
> Applied. Thanks.
Thank you Martin!
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2025-09-10 15:59 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-09-09 23:26 [PATCH v1 bpf] tcp_bpf: Call sk_msg_free() when tcp_bpf_send_verdict() fails to allocate psock->cork Kuniyuki Iwashima
2025-09-10 5:15 ` Martin KaFai Lau
2025-09-10 6:56 ` Kuniyuki Iwashima
2025-09-10 14:05 ` Martin KaFai Lau
2025-09-10 15:59 ` Kuniyuki Iwashima
2025-09-10 14:10 ` patchwork-bot+netdevbpf
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