diff mbox series

[net,v2] tun: Check tun device queue status in tun_chr_write_iter

Message ID 20220915123539.35956-1-liujian56@huawei.com (mailing list archive)
State Changes Requested
Delegated to: Netdev Maintainers
Headers show
Series [net,v2] tun: Check tun device queue status in tun_chr_write_iter | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net
netdev/fixes_present success Fixes tag present in non-next series
netdev/subject_prefix success Link
netdev/cover_letter success Single patches do not need cover letters
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers warning 1 maintainers not CCed: bpf@vger.kernel.org
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 11 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Liu Jian Sept. 15, 2022, 12:35 p.m. UTC 
syzbot found below warning:

------------[ cut here ]------------
geneve0 received packet on queue 3, but number of RX queues is 3
WARNING: CPU: 1 PID: 29734 at net/core/dev.c:4611 netif_get_rxqueue net/core/dev.c:4611 [inline]
WARNING: CPU: 1 PID: 29734 at net/core/dev.c:4611 netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683
Modules linked in:
CPU: 1 PID: 29734 Comm: syz-executor.0 Not tainted 5.10.0 #5
Hardware name: linux,dummy-virt (DT)
pstate: 60400005 (nZCv daif +PAN -UAO -TCO BTYPE=--)
pc : netif_get_rxqueue net/core/dev.c:4611 [inline]
pc : netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683
lr : netif_get_rxqueue net/core/dev.c:4611 [inline]
lr : netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683
sp : ffffa00016127770
x29: ffffa00016127770 x28: ffff3f4607d6acb4
x27: ffff3f4607d6acb0 x26: ffff3f4607d6ad20
x25: ffff3f461de3c000 x24: ffff3f4607d6ad28
x23: ffffa00010059000 x22: ffff3f4608719100
x21: 0000000000000003 x20: ffffa000161278a0
x19: ffff3f4607d6ac40 x18: 0000000000000000
x17: 0000000000000000 x16: 00000000f2f2f204
x15: 00000000f2f20000 x14: 6465766965636572
x13: 20306576656e6567 x12: ffff98b8ed3b924d
x11: 1ffff8b8ed3b924c x10: ffff98b8ed3b924c
x9 : ffffc5c76525c9c4 x8 : 0000000000000000
x7 : 0000000000000001 x6 : ffff98b8ed3b924c
x5 : ffff3f460f3b29c0 x4 : dfffa00000000000
x3 : ffffc5c765000000 x2 : 0000000000000000
x1 : 0000000000000000 x0 : ffff3f460f3b29c0
Call trace:
 netif_get_rxqueue net/core/dev.c:4611 [inline]
 netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683
 do_xdp_generic net/core/dev.c:4777 [inline]
 do_xdp_generic+0x9c/0x190 net/core/dev.c:4770
 tun_get_user+0xd94/0x2010 drivers/net/tun.c:1938
 tun_chr_write_iter+0x98/0x100 drivers/net/tun.c:2036
 call_write_iter include/linux/fs.h:1960 [inline]
 new_sync_write+0x260/0x370 fs/read_write.c:515
 vfs_write+0x51c/0x61c fs/read_write.c:602
 ksys_write+0xfc/0x200 fs/read_write.c:655
 __do_sys_write fs/read_write.c:667 [inline]
 __se_sys_write fs/read_write.c:664 [inline]
 __arm64_sys_write+0x50/0x60 fs/read_write.c:664
 __invoke_syscall arch/arm64/kernel/syscall.c:36 [inline]
 invoke_syscall arch/arm64/kernel/syscall.c:48 [inline]
 el0_svc_common.constprop.0+0xf4/0x414 arch/arm64/kernel/syscall.c:155
 do_el0_svc+0x50/0x11c arch/arm64/kernel/syscall.c:217
 el0_svc+0x20/0x30 arch/arm64/kernel/entry-common.c:353
 el0_sync_handler+0xe4/0x1e0 arch/arm64/kernel/entry-common.c:369
 el0_sync+0x148/0x180 arch/arm64/kernel/entry.S:683

This is because the detached queue is used to send data. Therefore, we need
to check the queue status in the tun_chr_write_iter function.

Fixes: cde8b15f1aab ("tuntap: add ioctl to attach or detach a file form tuntap device")
Signed-off-by: Liu Jian <liujian56@huawei.com>
---
v1->v2: add fixes tag
 drivers/net/tun.c | 5 +++++
 1 file changed, 5 insertions(+)

Comments

Jason Wang Sept. 16, 2022, 1:56 a.m. UTC | #1 
On Thu, Sep 15, 2022 at 8:34 PM Liu Jian <liujian56@huawei.com> wrote:
>
> syzbot found below warning:
>
> ------------[ cut here ]------------
> geneve0 received packet on queue 3, but number of RX queues is 3
> WARNING: CPU: 1 PID: 29734 at net/core/dev.c:4611 netif_get_rxqueue net/core/dev.c:4611 [inline]
> WARNING: CPU: 1 PID: 29734 at net/core/dev.c:4611 netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683
> Modules linked in:
> CPU: 1 PID: 29734 Comm: syz-executor.0 Not tainted 5.10.0 #5
> Hardware name: linux,dummy-virt (DT)
> pstate: 60400005 (nZCv daif +PAN -UAO -TCO BTYPE=--)
> pc : netif_get_rxqueue net/core/dev.c:4611 [inline]
> pc : netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683
> lr : netif_get_rxqueue net/core/dev.c:4611 [inline]
> lr : netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683
> sp : ffffa00016127770
> x29: ffffa00016127770 x28: ffff3f4607d6acb4
> x27: ffff3f4607d6acb0 x26: ffff3f4607d6ad20
> x25: ffff3f461de3c000 x24: ffff3f4607d6ad28
> x23: ffffa00010059000 x22: ffff3f4608719100
> x21: 0000000000000003 x20: ffffa000161278a0
> x19: ffff3f4607d6ac40 x18: 0000000000000000
> x17: 0000000000000000 x16: 00000000f2f2f204
> x15: 00000000f2f20000 x14: 6465766965636572
> x13: 20306576656e6567 x12: ffff98b8ed3b924d
> x11: 1ffff8b8ed3b924c x10: ffff98b8ed3b924c
> x9 : ffffc5c76525c9c4 x8 : 0000000000000000
> x7 : 0000000000000001 x6 : ffff98b8ed3b924c
> x5 : ffff3f460f3b29c0 x4 : dfffa00000000000
> x3 : ffffc5c765000000 x2 : 0000000000000000
> x1 : 0000000000000000 x0 : ffff3f460f3b29c0
> Call trace:
>  netif_get_rxqueue net/core/dev.c:4611 [inline]
>  netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683
>  do_xdp_generic net/core/dev.c:4777 [inline]
>  do_xdp_generic+0x9c/0x190 net/core/dev.c:4770
>  tun_get_user+0xd94/0x2010 drivers/net/tun.c:1938
>  tun_chr_write_iter+0x98/0x100 drivers/net/tun.c:2036
>  call_write_iter include/linux/fs.h:1960 [inline]
>  new_sync_write+0x260/0x370 fs/read_write.c:515
>  vfs_write+0x51c/0x61c fs/read_write.c:602
>  ksys_write+0xfc/0x200 fs/read_write.c:655
>  __do_sys_write fs/read_write.c:667 [inline]
>  __se_sys_write fs/read_write.c:664 [inline]
>  __arm64_sys_write+0x50/0x60 fs/read_write.c:664
>  __invoke_syscall arch/arm64/kernel/syscall.c:36 [inline]
>  invoke_syscall arch/arm64/kernel/syscall.c:48 [inline]
>  el0_svc_common.constprop.0+0xf4/0x414 arch/arm64/kernel/syscall.c:155
>  do_el0_svc+0x50/0x11c arch/arm64/kernel/syscall.c:217
>  el0_svc+0x20/0x30 arch/arm64/kernel/entry-common.c:353
>  el0_sync_handler+0xe4/0x1e0 arch/arm64/kernel/entry-common.c:369
>  el0_sync+0x148/0x180 arch/arm64/kernel/entry.S:683
>
> This is because the detached queue is used to send data. Therefore, we need
> to check the queue status in the tun_chr_write_iter function.
>
> Fixes: cde8b15f1aab ("tuntap: add ioctl to attach or detach a file form tuntap device")

Not sure this deserves a stable.

> Signed-off-by: Liu Jian <liujian56@huawei.com>
> ---
> v1->v2: add fixes tag
>  drivers/net/tun.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 259b2b84b2b3..261411c1a6bb 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -2019,6 +2019,11 @@ static ssize_t tun_chr_write_iter(struct kiocb *iocb, struct iov_iter *from)
>         if (!tun)
>                 return -EBADFD;
>
> +       if (tfile->detached) {

tfile->detached is synchronized through rtnl_lock which is probably
not suitable for the datapath. We probably need to rcuify this.

> +               tun_put(tun);
> +               return -ENETDOWN;

Another question is that can some user space depend on this behaviour?
I wonder if it's more safe to pretend the packet was received here?

Thanks

> +       }
> +
>         if ((file->f_flags & O_NONBLOCK) || (iocb->ki_flags & IOCB_NOWAIT))
>                 noblock = 1;
>
> --
> 2.17.1
>
Liu Jian Sept. 16, 2022, 7:04 a.m. UTC | #2 
> -----Original Message-----
> From: Jason Wang [mailto:jasowang@redhat.com]
> Sent: Friday, September 16, 2022 9:57 AM
> To: liujian (CE) <liujian56@huawei.com>
> Cc: davem <davem@davemloft.net>; Eric Dumazet
> <edumazet@google.com>; Jakub Kicinski <kuba@kernel.org>; Paolo Abeni
> <pabeni@redhat.com>; Alexei Starovoitov <ast@kernel.org>; Daniel
> Borkmann <daniel@iogearbox.net>; Jesper Dangaard Brouer
> <hawk@kernel.org>; John Fastabend <john.fastabend@gmail.com>; netdev
> <netdev@vger.kernel.org>
> Subject: Re: [PATCH net v2] tun: Check tun device queue status in
> tun_chr_write_iter
> 
> On Thu, Sep 15, 2022 at 8:34 PM Liu Jian <liujian56@huawei.com> wrote:
> >
> > syzbot found below warning:
> >
> > ------------[ cut here ]------------
> > geneve0 received packet on queue 3, but number of RX queues is 3
> > WARNING: CPU: 1 PID: 29734 at net/core/dev.c:4611 netif_get_rxqueue
> > net/core/dev.c:4611 [inline]
> > WARNING: CPU: 1 PID: 29734 at net/core/dev.c:4611
> > netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683 Modules
> linked in:
> > CPU: 1 PID: 29734 Comm: syz-executor.0 Not tainted 5.10.0 #5 Hardware
> > name: linux,dummy-virt (DT)
> > pstate: 60400005 (nZCv daif +PAN -UAO -TCO BTYPE=--) pc :
> > netif_get_rxqueue net/core/dev.c:4611 [inline] pc :
> > netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683 lr :
> > netif_get_rxqueue net/core/dev.c:4611 [inline] lr :
> > netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683 sp :
> > ffffa00016127770
> > x29: ffffa00016127770 x28: ffff3f4607d6acb4
> > x27: ffff3f4607d6acb0 x26: ffff3f4607d6ad20
> > x25: ffff3f461de3c000 x24: ffff3f4607d6ad28
> > x23: ffffa00010059000 x22: ffff3f4608719100
> > x21: 0000000000000003 x20: ffffa000161278a0
> > x19: ffff3f4607d6ac40 x18: 0000000000000000
> > x17: 0000000000000000 x16: 00000000f2f2f204
> > x15: 00000000f2f20000 x14: 6465766965636572
> > x13: 20306576656e6567 x12: ffff98b8ed3b924d
> > x11: 1ffff8b8ed3b924c x10: ffff98b8ed3b924c
> > x9 : ffffc5c76525c9c4 x8 : 0000000000000000
> > x7 : 0000000000000001 x6 : ffff98b8ed3b924c
> > x5 : ffff3f460f3b29c0 x4 : dfffa00000000000
> > x3 : ffffc5c765000000 x2 : 0000000000000000
> > x1 : 0000000000000000 x0 : ffff3f460f3b29c0 Call trace:
> >  netif_get_rxqueue net/core/dev.c:4611 [inline]
> >  netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683
> > do_xdp_generic net/core/dev.c:4777 [inline]
> >  do_xdp_generic+0x9c/0x190 net/core/dev.c:4770
> >  tun_get_user+0xd94/0x2010 drivers/net/tun.c:1938
> >  tun_chr_write_iter+0x98/0x100 drivers/net/tun.c:2036  call_write_iter
> > include/linux/fs.h:1960 [inline]
> >  new_sync_write+0x260/0x370 fs/read_write.c:515  vfs_write+0x51c/0x61c
> > fs/read_write.c:602
> >  ksys_write+0xfc/0x200 fs/read_write.c:655  __do_sys_write
> > fs/read_write.c:667 [inline]  __se_sys_write fs/read_write.c:664
> > [inline]
> >  __arm64_sys_write+0x50/0x60 fs/read_write.c:664  __invoke_syscall
> > arch/arm64/kernel/syscall.c:36 [inline]  invoke_syscall
> > arch/arm64/kernel/syscall.c:48 [inline]
> >  el0_svc_common.constprop.0+0xf4/0x414 arch/arm64/kernel/syscall.c:155
> > do_el0_svc+0x50/0x11c arch/arm64/kernel/syscall.c:217
> >  el0_svc+0x20/0x30 arch/arm64/kernel/entry-common.c:353
> >  el0_sync_handler+0xe4/0x1e0 arch/arm64/kernel/entry-common.c:369
> >  el0_sync+0x148/0x180 arch/arm64/kernel/entry.S:683
> >
> > This is because the detached queue is used to send data. Therefore, we
> > need to check the queue status in the tun_chr_write_iter function.
> >
> > Fixes: cde8b15f1aab ("tuntap: add ioctl to attach or detach a file
> > form tuntap device")
> 
> Not sure this deserves a stable.
> 
> > Signed-off-by: Liu Jian <liujian56@huawei.com>
> > ---
> > v1->v2: add fixes tag
> >  drivers/net/tun.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/net/tun.c b/drivers/net/tun.c index
> > 259b2b84b2b3..261411c1a6bb 100644
> > --- a/drivers/net/tun.c
> > +++ b/drivers/net/tun.c
> > @@ -2019,6 +2019,11 @@ static ssize_t tun_chr_write_iter(struct kiocb
> *iocb, struct iov_iter *from)
> >         if (!tun)
> >                 return -EBADFD;
> >
> > +       if (tfile->detached) {
> 
> tfile->detached is synchronized through rtnl_lock which is probably
> not suitable for the datapath. We probably need to rcuify this.
> 
> > +               tun_put(tun);
> > +               return -ENETDOWN;
> 
> Another question is that can some user space depend on this behaviour?
> I wonder if it's more safe to pretend the packet was received here?
> 
Thanks for your review. I don't know whether there was any depend on this behavior.
If that's the case, I think it's better to keep this warning.
What is your opinion on this warning?

> Thanks
> 
> > +       }
> > +
> >         if ((file->f_flags & O_NONBLOCK) || (iocb->ki_flags & IOCB_NOWAIT))
> >                 noblock = 1;
> >
> > --
> > 2.17.1
> >
Liu Jian Sept. 22, 2022, 1:45 p.m. UTC | #3 
> -----Original Message-----
> From: liujian (CE)
> Sent: Friday, September 16, 2022 3:05 PM
> To: 'Jason Wang' <jasowang@redhat.com>
> Cc: davem <davem@davemloft.net>; Eric Dumazet
> <edumazet@google.com>; Jakub Kicinski <kuba@kernel.org>; Paolo Abeni
> <pabeni@redhat.com>; Alexei Starovoitov <ast@kernel.org>; Daniel
> Borkmann <daniel@iogearbox.net>; Jesper Dangaard Brouer
> <hawk@kernel.org>; John Fastabend <john.fastabend@gmail.com>; netdev
> <netdev@vger.kernel.org>
> Subject: RE: [PATCH net v2] tun: Check tun device queue status in
> tun_chr_write_iter
> 
> 
> 
> > -----Original Message-----
> > From: Jason Wang [mailto:jasowang@redhat.com]
> > Sent: Friday, September 16, 2022 9:57 AM
> > To: liujian (CE) <liujian56@huawei.com>
> > Cc: davem <davem@davemloft.net>; Eric Dumazet
> <edumazet@google.com>;
> > Jakub Kicinski <kuba@kernel.org>; Paolo Abeni <pabeni@redhat.com>;
> > Alexei Starovoitov <ast@kernel.org>; Daniel Borkmann
> > <daniel@iogearbox.net>; Jesper Dangaard Brouer <hawk@kernel.org>;
> John
> > Fastabend <john.fastabend@gmail.com>; netdev
> <netdev@vger.kernel.org>
> > Subject: Re: [PATCH net v2] tun: Check tun device queue status in
> > tun_chr_write_iter
> >
> > On Thu, Sep 15, 2022 at 8:34 PM Liu Jian <liujian56@huawei.com> wrote:
> > >
> > > syzbot found below warning:
> > >
> > > ------------[ cut here ]------------
> > > geneve0 received packet on queue 3, but number of RX queues is 3
> > > WARNING: CPU: 1 PID: 29734 at net/core/dev.c:4611 netif_get_rxqueue
> > > net/core/dev.c:4611 [inline]
> > > WARNING: CPU: 1 PID: 29734 at net/core/dev.c:4611
> > > netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683 Modules
> > linked in:
> > > CPU: 1 PID: 29734 Comm: syz-executor.0 Not tainted 5.10.0 #5
> > > Hardware
> > > name: linux,dummy-virt (DT)
> > > pstate: 60400005 (nZCv daif +PAN -UAO -TCO BTYPE=--) pc :
> > > netif_get_rxqueue net/core/dev.c:4611 [inline] pc :
> > > netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683 lr :
> > > netif_get_rxqueue net/core/dev.c:4611 [inline] lr :
> > > netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683 sp :
> > > ffffa00016127770
> > > x29: ffffa00016127770 x28: ffff3f4607d6acb4
> > > x27: ffff3f4607d6acb0 x26: ffff3f4607d6ad20
> > > x25: ffff3f461de3c000 x24: ffff3f4607d6ad28
> > > x23: ffffa00010059000 x22: ffff3f4608719100
> > > x21: 0000000000000003 x20: ffffa000161278a0
> > > x19: ffff3f4607d6ac40 x18: 0000000000000000
> > > x17: 0000000000000000 x16: 00000000f2f2f204
> > > x15: 00000000f2f20000 x14: 6465766965636572
> > > x13: 20306576656e6567 x12: ffff98b8ed3b924d
> > > x11: 1ffff8b8ed3b924c x10: ffff98b8ed3b924c
> > > x9 : ffffc5c76525c9c4 x8 : 0000000000000000
> > > x7 : 0000000000000001 x6 : ffff98b8ed3b924c
> > > x5 : ffff3f460f3b29c0 x4 : dfffa00000000000
> > > x3 : ffffc5c765000000 x2 : 0000000000000000
> > > x1 : 0000000000000000 x0 : ffff3f460f3b29c0 Call trace:
> > >  netif_get_rxqueue net/core/dev.c:4611 [inline]
> > >  netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683
> > > do_xdp_generic net/core/dev.c:4777 [inline]
> > >  do_xdp_generic+0x9c/0x190 net/core/dev.c:4770
> > >  tun_get_user+0xd94/0x2010 drivers/net/tun.c:1938
> > >  tun_chr_write_iter+0x98/0x100 drivers/net/tun.c:2036
> > > call_write_iter
> > > include/linux/fs.h:1960 [inline]
> > >  new_sync_write+0x260/0x370 fs/read_write.c:515
> > > vfs_write+0x51c/0x61c
> > > fs/read_write.c:602
> > >  ksys_write+0xfc/0x200 fs/read_write.c:655  __do_sys_write
> > > fs/read_write.c:667 [inline]  __se_sys_write fs/read_write.c:664
> > > [inline]
> > >  __arm64_sys_write+0x50/0x60 fs/read_write.c:664  __invoke_syscall
> > > arch/arm64/kernel/syscall.c:36 [inline]  invoke_syscall
> > > arch/arm64/kernel/syscall.c:48 [inline]
> > >  el0_svc_common.constprop.0+0xf4/0x414
> > > arch/arm64/kernel/syscall.c:155 do_el0_svc+0x50/0x11c
> > > arch/arm64/kernel/syscall.c:217
> > >  el0_svc+0x20/0x30 arch/arm64/kernel/entry-common.c:353
> > >  el0_sync_handler+0xe4/0x1e0 arch/arm64/kernel/entry-common.c:369
> > >  el0_sync+0x148/0x180 arch/arm64/kernel/entry.S:683
> > >
> > > This is because the detached queue is used to send data. Therefore,
> > > we need to check the queue status in the tun_chr_write_iter function.
> > >
> > > Fixes: cde8b15f1aab ("tuntap: add ioctl to attach or detach a file
> > > form tuntap device")
> >
Hello, 
Sorry, fixes tag is wrong. The warning should be introduced by commit 3fe260e00cd0 (" net: tun: record RX queue in skb before do_xdp_generic() "). Before this, do_xdp_generic always uses queue0. Therefore, when the warning is generated due to detached, queue0 is used and is printed only once, which is harmless. So it's not a problem. 
What do you think about  this warning?

> > Not sure this deserves a stable.
> >
> > > Signed-off-by: Liu Jian <liujian56@huawei.com>
> > > ---
> > > v1->v2: add fixes tag
> > >  drivers/net/tun.c | 5 +++++
> > >  1 file changed, 5 insertions(+)
> > >
> > > diff --git a/drivers/net/tun.c b/drivers/net/tun.c index
> > > 259b2b84b2b3..261411c1a6bb 100644
> > > --- a/drivers/net/tun.c
> > > +++ b/drivers/net/tun.c
> > > @@ -2019,6 +2019,11 @@ static ssize_t tun_chr_write_iter(struct
> > > kiocb
> > *iocb, struct iov_iter *from)
> > >         if (!tun)
> > >                 return -EBADFD;
> > >
> > > +       if (tfile->detached) {
> >
> > tfile->detached is synchronized through rtnl_lock which is probably
> > not suitable for the datapath. We probably need to rcuify this.
> >
> > > +               tun_put(tun);
> > > +               return -ENETDOWN;
> >
> > Another question is that can some user space depend on this behaviour?
> > I wonder if it's more safe to pretend the packet was received here?
> >
> Thanks for your review. I don't know whether there was any depend on this
> behavior.
> If that's the case, I think it's better to keep this warning.
> What is your opinion on this warning?
> 
> > Thanks
> >
> > > +       }
> > > +
> > >         if ((file->f_flags & O_NONBLOCK) || (iocb->ki_flags & IOCB_NOWAIT))
> > >                 noblock = 1;
> > >
> > > --
> > > 2.17.1
> > >
Jason Wang Sept. 23, 2022, 3:23 a.m. UTC | #4 
On Thu, Sep 22, 2022 at 9:45 PM liujian (CE) <liujian56@huawei.com> wrote:
>
>
>
> > -----Original Message-----
> > From: liujian (CE)
> > Sent: Friday, September 16, 2022 3:05 PM
> > To: 'Jason Wang' <jasowang@redhat.com>
> > Cc: davem <davem@davemloft.net>; Eric Dumazet
> > <edumazet@google.com>; Jakub Kicinski <kuba@kernel.org>; Paolo Abeni
> > <pabeni@redhat.com>; Alexei Starovoitov <ast@kernel.org>; Daniel
> > Borkmann <daniel@iogearbox.net>; Jesper Dangaard Brouer
> > <hawk@kernel.org>; John Fastabend <john.fastabend@gmail.com>; netdev
> > <netdev@vger.kernel.org>
> > Subject: RE: [PATCH net v2] tun: Check tun device queue status in
> > tun_chr_write_iter
> >
> >
> >
> > > -----Original Message-----
> > > From: Jason Wang [mailto:jasowang@redhat.com]
> > > Sent: Friday, September 16, 2022 9:57 AM
> > > To: liujian (CE) <liujian56@huawei.com>
> > > Cc: davem <davem@davemloft.net>; Eric Dumazet
> > <edumazet@google.com>;
> > > Jakub Kicinski <kuba@kernel.org>; Paolo Abeni <pabeni@redhat.com>;
> > > Alexei Starovoitov <ast@kernel.org>; Daniel Borkmann
> > > <daniel@iogearbox.net>; Jesper Dangaard Brouer <hawk@kernel.org>;
> > John
> > > Fastabend <john.fastabend@gmail.com>; netdev
> > <netdev@vger.kernel.org>
> > > Subject: Re: [PATCH net v2] tun: Check tun device queue status in
> > > tun_chr_write_iter
> > >
> > > On Thu, Sep 15, 2022 at 8:34 PM Liu Jian <liujian56@huawei.com> wrote:
> > > >
> > > > syzbot found below warning:
> > > >
> > > > ------------[ cut here ]------------
> > > > geneve0 received packet on queue 3, but number of RX queues is 3
> > > > WARNING: CPU: 1 PID: 29734 at net/core/dev.c:4611 netif_get_rxqueue
> > > > net/core/dev.c:4611 [inline]
> > > > WARNING: CPU: 1 PID: 29734 at net/core/dev.c:4611
> > > > netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683 Modules
> > > linked in:
> > > > CPU: 1 PID: 29734 Comm: syz-executor.0 Not tainted 5.10.0 #5
> > > > Hardware
> > > > name: linux,dummy-virt (DT)
> > > > pstate: 60400005 (nZCv daif +PAN -UAO -TCO BTYPE=--) pc :
> > > > netif_get_rxqueue net/core/dev.c:4611 [inline] pc :
> > > > netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683 lr :
> > > > netif_get_rxqueue net/core/dev.c:4611 [inline] lr :
> > > > netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683 sp :
> > > > ffffa00016127770
> > > > x29: ffffa00016127770 x28: ffff3f4607d6acb4
> > > > x27: ffff3f4607d6acb0 x26: ffff3f4607d6ad20
> > > > x25: ffff3f461de3c000 x24: ffff3f4607d6ad28
> > > > x23: ffffa00010059000 x22: ffff3f4608719100
> > > > x21: 0000000000000003 x20: ffffa000161278a0
> > > > x19: ffff3f4607d6ac40 x18: 0000000000000000
> > > > x17: 0000000000000000 x16: 00000000f2f2f204
> > > > x15: 00000000f2f20000 x14: 6465766965636572
> > > > x13: 20306576656e6567 x12: ffff98b8ed3b924d
> > > > x11: 1ffff8b8ed3b924c x10: ffff98b8ed3b924c
> > > > x9 : ffffc5c76525c9c4 x8 : 0000000000000000
> > > > x7 : 0000000000000001 x6 : ffff98b8ed3b924c
> > > > x5 : ffff3f460f3b29c0 x4 : dfffa00000000000
> > > > x3 : ffffc5c765000000 x2 : 0000000000000000
> > > > x1 : 0000000000000000 x0 : ffff3f460f3b29c0 Call trace:
> > > >  netif_get_rxqueue net/core/dev.c:4611 [inline]
> > > >  netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683
> > > > do_xdp_generic net/core/dev.c:4777 [inline]
> > > >  do_xdp_generic+0x9c/0x190 net/core/dev.c:4770
> > > >  tun_get_user+0xd94/0x2010 drivers/net/tun.c:1938
> > > >  tun_chr_write_iter+0x98/0x100 drivers/net/tun.c:2036
> > > > call_write_iter
> > > > include/linux/fs.h:1960 [inline]
> > > >  new_sync_write+0x260/0x370 fs/read_write.c:515
> > > > vfs_write+0x51c/0x61c
> > > > fs/read_write.c:602
> > > >  ksys_write+0xfc/0x200 fs/read_write.c:655  __do_sys_write
> > > > fs/read_write.c:667 [inline]  __se_sys_write fs/read_write.c:664
> > > > [inline]
> > > >  __arm64_sys_write+0x50/0x60 fs/read_write.c:664  __invoke_syscall
> > > > arch/arm64/kernel/syscall.c:36 [inline]  invoke_syscall
> > > > arch/arm64/kernel/syscall.c:48 [inline]
> > > >  el0_svc_common.constprop.0+0xf4/0x414
> > > > arch/arm64/kernel/syscall.c:155 do_el0_svc+0x50/0x11c
> > > > arch/arm64/kernel/syscall.c:217
> > > >  el0_svc+0x20/0x30 arch/arm64/kernel/entry-common.c:353
> > > >  el0_sync_handler+0xe4/0x1e0 arch/arm64/kernel/entry-common.c:369
> > > >  el0_sync+0x148/0x180 arch/arm64/kernel/entry.S:683
> > > >
> > > > This is because the detached queue is used to send data. Therefore,
> > > > we need to check the queue status in the tun_chr_write_iter function.
> > > >
> > > > Fixes: cde8b15f1aab ("tuntap: add ioctl to attach or detach a file
> > > > form tuntap device")
> > >
> Hello,
> Sorry, fixes tag is wrong. The warning should be introduced by commit 3fe260e00cd0 (" net: tun: record RX queue in skb before do_xdp_generic() "). Before this, do_xdp_generic always uses queue0. Therefore, when the warning is generated due to detached, queue0 is used and is printed only once, which is harmless. So it's not a problem.
> What do you think about  this warning?

I tend to keep this warning (it might be too late to fix).

Thanks

>
> > > Not sure this deserves a stable.
> > >
> > > > Signed-off-by: Liu Jian <liujian56@huawei.com>
> > > > ---
> > > > v1->v2: add fixes tag
> > > >  drivers/net/tun.c | 5 +++++
> > > >  1 file changed, 5 insertions(+)
> > > >
> > > > diff --git a/drivers/net/tun.c b/drivers/net/tun.c index
> > > > 259b2b84b2b3..261411c1a6bb 100644
> > > > --- a/drivers/net/tun.c
> > > > +++ b/drivers/net/tun.c
> > > > @@ -2019,6 +2019,11 @@ static ssize_t tun_chr_write_iter(struct
> > > > kiocb
> > > *iocb, struct iov_iter *from)
> > > >         if (!tun)
> > > >                 return -EBADFD;
> > > >
> > > > +       if (tfile->detached) {
> > >
> > > tfile->detached is synchronized through rtnl_lock which is probably
> > > not suitable for the datapath. We probably need to rcuify this.
> > >
> > > > +               tun_put(tun);
> > > > +               return -ENETDOWN;
> > >
> > > Another question is that can some user space depend on this behaviour?
> > > I wonder if it's more safe to pretend the packet was received here?
> > >
> > Thanks for your review. I don't know whether there was any depend on this
> > behavior.
> > If that's the case, I think it's better to keep this warning.
> > What is your opinion on this warning?
> >
> > > Thanks
> > >
> > > > +       }
> > > > +
> > > >         if ((file->f_flags & O_NONBLOCK) || (iocb->ki_flags & IOCB_NOWAIT))
> > > >                 noblock = 1;
> > > >
> > > > --
> > > > 2.17.1
> > > >
>
diff mbox series

Patch

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 259b2b84b2b3..261411c1a6bb 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -2019,6 +2019,11 @@  static ssize_t tun_chr_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	if (!tun)
 		return -EBADFD;
 
+	if (tfile->detached) {
+		tun_put(tun);
+		return -ENETDOWN;
+	}
+
 	if ((file->f_flags & O_NONBLOCK) || (iocb->ki_flags & IOCB_NOWAIT))
 		noblock = 1;