| Message ID | 20210226092456.27126-1-o.rempel@pengutronix.de (mailing list archive) |
|---|---|
| State | Awaiting Upstream |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,v4,1/1] can: can_skb_set_owner(): fix ref counting if socket was closed before setting skb ownership | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for net |
| netdev/subject_prefix | success | Link |
| netdev/cc_maintainers | success | CCed 5 of 5 maintainers |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 3 this patch: 3 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 14 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 3 this patch: 3 |
| netdev/header_inline | success | Link |
| netdev/stable | success | Stable not CCed |
On 26.02.21 10:24, Oleksij Rempel wrote: > There are two ref count variables controlling the free()ing of a socket: > - struct sock::sk_refcnt - which is changed by sock_hold()/sock_put() > - struct sock::sk_wmem_alloc - which accounts the memory allocated by > the skbs in the send path. > > In case there are still TX skbs on the fly and the socket() is closed, > the struct sock::sk_refcnt reaches 0. In the TX-path the CAN stack > clones an "echo" skb, calls sock_hold() on the original socket and > references it. This produces the following back trace: > > | WARNING: CPU: 0 PID: 280 at lib/refcount.c:25 refcount_warn_saturate+0x114/0x134 > | refcount_t: addition on 0; use-after-free. > | Modules linked in: coda_vpu(E) v4l2_jpeg(E) videobuf2_vmalloc(E) imx_vdoa(E) > | CPU: 0 PID: 280 Comm: test_can.sh Tainted: G E 5.11.0-04577-gf8ff6603c617 #203 > | Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree) > | Backtrace: > | [<80bafea4>] (dump_backtrace) from [<80bb0280>] (show_stack+0x20/0x24) r7:00000000 r6:600f0113 r5:00000000 r4:81441220 > | [<80bb0260>] (show_stack) from [<80bb593c>] (dump_stack+0xa0/0xc8) > | [<80bb589c>] (dump_stack) from [<8012b268>] (__warn+0xd4/0x114) r9:00000019 r8:80f4a8c2 r7:83e4150c r6:00000000 r5:00000009 r4:80528f90 > | [<8012b194>] (__warn) from [<80bb09c4>] (warn_slowpath_fmt+0x88/0xc8) r9:83f26400 r8:80f4a8d1 r7:00000009 r6:80528f90 r5:00000019 r4:80f4a8c2 > | [<80bb0940>] (warn_slowpath_fmt) from [<80528f90>] (refcount_warn_saturate+0x114/0x134) r8:00000000 r7:00000000 r6:82b44000 r5:834e5600 r4:83f4d540 > | [<80528e7c>] (refcount_warn_saturate) from [<8079a4c8>] (__refcount_add.constprop.0+0x4c/0x50) > | [<8079a47c>] (__refcount_add.constprop.0) from [<8079a57c>] (can_put_echo_skb+0xb0/0x13c) > | [<8079a4cc>] (can_put_echo_skb) from [<8079ba98>] (flexcan_start_xmit+0x1c4/0x230) r9:00000010 r8:83f48610 r7:0fdc0000 r6:0c080000 r5:82b44000 r4:834e5600 > | [<8079b8d4>] (flexcan_start_xmit) from [<80969078>] (netdev_start_xmit+0x44/0x70) r9:814c0ba0 r8:80c8790c r7:00000000 r6:834e5600 r5:82b44000 r4:82ab1f00 > | [<80969034>] (netdev_start_xmit) from [<809725a4>] (dev_hard_start_xmit+0x19c/0x318) r9:814c0ba0 r8:00000000 r7:82ab1f00 r6:82b44000 r5:00000000 r4:834e5600 > | [<80972408>] (dev_hard_start_xmit) from [<809c6584>] (sch_direct_xmit+0xcc/0x264) r10:834e5600 r9:00000000 r8:00000000 r7:82b44000 r6:82ab1f00 r5:834e5600 r4:83f27400 > | [<809c64b8>] (sch_direct_xmit) from [<809c6c0c>] (__qdisc_run+0x4f0/0x534) > > To fix this problem, only set skb ownership to sockets which have still > a ref count > 0. > > Cc: Oliver Hartkopp <socketcan@hartkopp.net> > Cc: Andre Naujoks <nautsch2@gmail.com> > Suggested-by: Eric Dumazet <edumazet@google.com> > Fixes: 0ae89beb283a ("can: add destructor for self generated skbs") > Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> > --- > include/linux/can/skb.h | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/include/linux/can/skb.h b/include/linux/can/skb.h > index 685f34cfba20..d82018cc0d0b 100644 > --- a/include/linux/can/skb.h > +++ b/include/linux/can/skb.h > @@ -65,8 +65,12 @@ static inline void can_skb_reserve(struct sk_buff *skb) > > static inline void can_skb_set_owner(struct sk_buff *skb, struct sock *sk) > { > - if (sk) { > - sock_hold(sk); > + /* > + * If the socket has already been closed by user space, the refcount may > + * already be 0 (and the socket will be freed after the last TX skb has > + * been freed). So only increase socket refcount if the refcount is > 0. > + */ > + if (sk && refcount_inc_not_zero(&sk->sk_refcnt)) { > skb->destructor = sock_efree; > skb->sk = sk; > } Ah, now I got the problem. You are replacing sock_hold(). Maybe I was a bit slow-witted here - but with the comment it is ok. Reviewed-by: Oliver Hartkopp <socketcan@hartkopp.net> Many thanks! Oliver
> -----Original Message----- > From: Oleksij Rempel <o.rempel@pengutronix.de> > Sent: 2021年2月26日 17:25 > To: mkl@pengutronix.de; David S. Miller <davem@davemloft.net>; Jakub > Kicinski <kuba@kernel.org>; Oliver Hartkopp <socketcan@hartkopp.net>; > Robin van der Gracht <robin@protonic.nl> > Cc: Oleksij Rempel <o.rempel@pengutronix.de>; Andre Naujoks > <nautsch2@gmail.com>; Eric Dumazet <edumazet@google.com>; > kernel@pengutronix.de; linux-can@vger.kernel.org; netdev@vger.kernel.org; > linux-kernel@vger.kernel.org > Subject: [PATCH net v4 1/1] can: can_skb_set_owner(): fix ref counting if socket > was closed before setting skb ownership > > There are two ref count variables controlling the free()ing of a socket: > - struct sock::sk_refcnt - which is changed by sock_hold()/sock_put() > - struct sock::sk_wmem_alloc - which accounts the memory allocated by > the skbs in the send path. > > In case there are still TX skbs on the fly and the socket() is closed, the struct > sock::sk_refcnt reaches 0. In the TX-path the CAN stack clones an "echo" skb, > calls sock_hold() on the original socket and references it. This produces the > following back trace: > > | WARNING: CPU: 0 PID: 280 at lib/refcount.c:25 > | refcount_warn_saturate+0x114/0x134 > | refcount_t: addition on 0; use-after-free. > | Modules linked in: coda_vpu(E) v4l2_jpeg(E) videobuf2_vmalloc(E) > imx_vdoa(E) > | CPU: 0 PID: 280 Comm: test_can.sh Tainted: G E > 5.11.0-04577-gf8ff6603c617 #203 > | Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree) > | Backtrace: > | [<80bafea4>] (dump_backtrace) from [<80bb0280>] (show_stack+0x20/0x24) > | r7:00000000 r6:600f0113 r5:00000000 r4:81441220 [<80bb0260>] > | (show_stack) from [<80bb593c>] (dump_stack+0xa0/0xc8) [<80bb589c>] > | (dump_stack) from [<8012b268>] (__warn+0xd4/0x114) r9:00000019 > | r8:80f4a8c2 r7:83e4150c r6:00000000 r5:00000009 r4:80528f90 > | [<8012b194>] (__warn) from [<80bb09c4>] (warn_slowpath_fmt+0x88/0xc8) > | r9:83f26400 r8:80f4a8d1 r7:00000009 r6:80528f90 r5:00000019 > | r4:80f4a8c2 [<80bb0940>] (warn_slowpath_fmt) from [<80528f90>] > | (refcount_warn_saturate+0x114/0x134) r8:00000000 r7:00000000 > | r6:82b44000 r5:834e5600 r4:83f4d540 [<80528e7c>] > | (refcount_warn_saturate) from [<8079a4c8>] > | (__refcount_add.constprop.0+0x4c/0x50) > | [<8079a47c>] (__refcount_add.constprop.0) from [<8079a57c>] > | (can_put_echo_skb+0xb0/0x13c) [<8079a4cc>] (can_put_echo_skb) from > | [<8079ba98>] (flexcan_start_xmit+0x1c4/0x230) r9:00000010 r8:83f48610 > | r7:0fdc0000 r6:0c080000 r5:82b44000 r4:834e5600 [<8079b8d4>] > | (flexcan_start_xmit) from [<80969078>] (netdev_start_xmit+0x44/0x70) > | r9:814c0ba0 r8:80c8790c r7:00000000 r6:834e5600 r5:82b44000 > | r4:82ab1f00 [<80969034>] (netdev_start_xmit) from [<809725a4>] > | (dev_hard_start_xmit+0x19c/0x318) r9:814c0ba0 r8:00000000 r7:82ab1f00 > | r6:82b44000 r5:00000000 r4:834e5600 [<80972408>] (dev_hard_start_xmit) > | from [<809c6584>] (sch_direct_xmit+0xcc/0x264) r10:834e5600 > | r9:00000000 r8:00000000 r7:82b44000 r6:82ab1f00 r5:834e5600 > | r4:83f27400 [<809c64b8>] (sch_direct_xmit) from [<809c6c0c>] > | (__qdisc_run+0x4f0/0x534) > > To fix this problem, only set skb ownership to sockets which have still a ref > count > 0. > > Cc: Oliver Hartkopp <socketcan@hartkopp.net> > Cc: Andre Naujoks <nautsch2@gmail.com> > Suggested-by: Eric Dumazet <edumazet@google.com> > Fixes: 0ae89beb283a ("can: add destructor for self generated skbs") > Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> I will give out a test result tomorrow when the board is available.
> -----Original Message----- > From: Joakim Zhang <qiangqing.zhang@nxp.com> > Sent: 2021年3月1日 18:57 > To: Oleksij Rempel <o.rempel@pengutronix.de>; mkl@pengutronix.de; David S. > Miller <davem@davemloft.net>; Jakub Kicinski <kuba@kernel.org>; Oliver > Hartkopp <socketcan@hartkopp.net>; Robin van der Gracht > <robin@protonic.nl> > Cc: Andre Naujoks <nautsch2@gmail.com>; Eric Dumazet > <edumazet@google.com>; kernel@pengutronix.de; linux-can@vger.kernel.org; > netdev@vger.kernel.org; linux-kernel@vger.kernel.org > Subject: RE: [PATCH net v4 1/1] can: can_skb_set_owner(): fix ref counting if > socket was closed before setting skb ownership > > > > -----Original Message----- > > From: Oleksij Rempel <o.rempel@pengutronix.de> > > Sent: 2021年2月26日 17:25 > > To: mkl@pengutronix.de; David S. Miller <davem@davemloft.net>; Jakub > > Kicinski <kuba@kernel.org>; Oliver Hartkopp <socketcan@hartkopp.net>; > > Robin van der Gracht <robin@protonic.nl> > > Cc: Oleksij Rempel <o.rempel@pengutronix.de>; Andre Naujoks > > <nautsch2@gmail.com>; Eric Dumazet <edumazet@google.com>; > > kernel@pengutronix.de; linux-can@vger.kernel.org; > > netdev@vger.kernel.org; linux-kernel@vger.kernel.org > > Subject: [PATCH net v4 1/1] can: can_skb_set_owner(): fix ref counting > > if socket was closed before setting skb ownership > > > > There are two ref count variables controlling the free()ing of a socket: > > - struct sock::sk_refcnt - which is changed by sock_hold()/sock_put() > > - struct sock::sk_wmem_alloc - which accounts the memory allocated by > > the skbs in the send path. > > > > In case there are still TX skbs on the fly and the socket() is closed, > > the struct sock::sk_refcnt reaches 0. In the TX-path the CAN stack > > clones an "echo" skb, calls sock_hold() on the original socket and > > references it. This produces the following back trace: > > > > | WARNING: CPU: 0 PID: 280 at lib/refcount.c:25 > > | refcount_warn_saturate+0x114/0x134 > > | refcount_t: addition on 0; use-after-free. > > | Modules linked in: coda_vpu(E) v4l2_jpeg(E) videobuf2_vmalloc(E) > > imx_vdoa(E) > > | CPU: 0 PID: 280 Comm: test_can.sh Tainted: G E > > 5.11.0-04577-gf8ff6603c617 #203 > > | Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree) > > | Backtrace: > > | [<80bafea4>] (dump_backtrace) from [<80bb0280>] > > | (show_stack+0x20/0x24) > > | r7:00000000 r6:600f0113 r5:00000000 r4:81441220 [<80bb0260>] > > | (show_stack) from [<80bb593c>] (dump_stack+0xa0/0xc8) [<80bb589c>] > > | (dump_stack) from [<8012b268>] (__warn+0xd4/0x114) r9:00000019 > > | r8:80f4a8c2 r7:83e4150c r6:00000000 r5:00000009 r4:80528f90 > > | [<8012b194>] (__warn) from [<80bb09c4>] > > | (warn_slowpath_fmt+0x88/0xc8) > > | r9:83f26400 r8:80f4a8d1 r7:00000009 r6:80528f90 r5:00000019 > > | r4:80f4a8c2 [<80bb0940>] (warn_slowpath_fmt) from [<80528f90>] > > | (refcount_warn_saturate+0x114/0x134) r8:00000000 r7:00000000 > > | r6:82b44000 r5:834e5600 r4:83f4d540 [<80528e7c>] > > | (refcount_warn_saturate) from [<8079a4c8>] > > | (__refcount_add.constprop.0+0x4c/0x50) > > | [<8079a47c>] (__refcount_add.constprop.0) from [<8079a57c>] > > | (can_put_echo_skb+0xb0/0x13c) [<8079a4cc>] (can_put_echo_skb) from > > | [<8079ba98>] (flexcan_start_xmit+0x1c4/0x230) r9:00000010 > > | r8:83f48610 > > | r7:0fdc0000 r6:0c080000 r5:82b44000 r4:834e5600 [<8079b8d4>] > > | (flexcan_start_xmit) from [<80969078>] (netdev_start_xmit+0x44/0x70) > > | r9:814c0ba0 r8:80c8790c r7:00000000 r6:834e5600 r5:82b44000 > > | r4:82ab1f00 [<80969034>] (netdev_start_xmit) from [<809725a4>] > > | (dev_hard_start_xmit+0x19c/0x318) r9:814c0ba0 r8:00000000 > > | r7:82ab1f00 > > | r6:82b44000 r5:00000000 r4:834e5600 [<80972408>] > > | (dev_hard_start_xmit) from [<809c6584>] (sch_direct_xmit+0xcc/0x264) > > | r10:834e5600 > > | r9:00000000 r8:00000000 r7:82b44000 r6:82ab1f00 r5:834e5600 > > | r4:83f27400 [<809c64b8>] (sch_direct_xmit) from [<809c6c0c>] > > | (__qdisc_run+0x4f0/0x534) > > > > To fix this problem, only set skb ownership to sockets which have > > still a ref count > 0. > > > > Cc: Oliver Hartkopp <socketcan@hartkopp.net> > > Cc: Andre Naujoks <nautsch2@gmail.com> > > Suggested-by: Eric Dumazet <edumazet@google.com> > > Fixes: 0ae89beb283a ("can: add destructor for self generated skbs") > > Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> > > I will give out a test result tomorrow when the board is available.
diff --git a/include/linux/can/skb.h b/include/linux/can/skb.h index 685f34cfba20..d82018cc0d0b 100644 --- a/include/linux/can/skb.h +++ b/include/linux/can/skb.h @@ -65,8 +65,12 @@ static inline void can_skb_reserve(struct sk_buff *skb) static inline void can_skb_set_owner(struct sk_buff *skb, struct sock *sk) { - if (sk) { - sock_hold(sk); + /* + * If the socket has already been closed by user space, the refcount may + * already be 0 (and the socket will be freed after the last TX skb has + * been freed). So only increase socket refcount if the refcount is > 0. + */ + if (sk && refcount_inc_not_zero(&sk->sk_refcnt)) { skb->destructor = sock_efree; skb->sk = sk; }
There are two ref count variables controlling the free()ing of a socket: - struct sock::sk_refcnt - which is changed by sock_hold()/sock_put() - struct sock::sk_wmem_alloc - which accounts the memory allocated by the skbs in the send path. In case there are still TX skbs on the fly and the socket() is closed, the struct sock::sk_refcnt reaches 0. In the TX-path the CAN stack clones an "echo" skb, calls sock_hold() on the original socket and references it. This produces the following back trace: | WARNING: CPU: 0 PID: 280 at lib/refcount.c:25 refcount_warn_saturate+0x114/0x134 | refcount_t: addition on 0; use-after-free. | Modules linked in: coda_vpu(E) v4l2_jpeg(E) videobuf2_vmalloc(E) imx_vdoa(E) | CPU: 0 PID: 280 Comm: test_can.sh Tainted: G E 5.11.0-04577-gf8ff6603c617 #203 | Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree) | Backtrace: | [<80bafea4>] (dump_backtrace) from [<80bb0280>] (show_stack+0x20/0x24) r7:00000000 r6:600f0113 r5:00000000 r4:81441220 | [<80bb0260>] (show_stack) from [<80bb593c>] (dump_stack+0xa0/0xc8) | [<80bb589c>] (dump_stack) from [<8012b268>] (__warn+0xd4/0x114) r9:00000019 r8:80f4a8c2 r7:83e4150c r6:00000000 r5:00000009 r4:80528f90 | [<8012b194>] (__warn) from [<80bb09c4>] (warn_slowpath_fmt+0x88/0xc8) r9:83f26400 r8:80f4a8d1 r7:00000009 r6:80528f90 r5:00000019 r4:80f4a8c2 | [<80bb0940>] (warn_slowpath_fmt) from [<80528f90>] (refcount_warn_saturate+0x114/0x134) r8:00000000 r7:00000000 r6:82b44000 r5:834e5600 r4:83f4d540 | [<80528e7c>] (refcount_warn_saturate) from [<8079a4c8>] (__refcount_add.constprop.0+0x4c/0x50) | [<8079a47c>] (__refcount_add.constprop.0) from [<8079a57c>] (can_put_echo_skb+0xb0/0x13c) | [<8079a4cc>] (can_put_echo_skb) from [<8079ba98>] (flexcan_start_xmit+0x1c4/0x230) r9:00000010 r8:83f48610 r7:0fdc0000 r6:0c080000 r5:82b44000 r4:834e5600 | [<8079b8d4>] (flexcan_start_xmit) from [<80969078>] (netdev_start_xmit+0x44/0x70) r9:814c0ba0 r8:80c8790c r7:00000000 r6:834e5600 r5:82b44000 r4:82ab1f00 | [<80969034>] (netdev_start_xmit) from [<809725a4>] (dev_hard_start_xmit+0x19c/0x318) r9:814c0ba0 r8:00000000 r7:82ab1f00 r6:82b44000 r5:00000000 r4:834e5600 | [<80972408>] (dev_hard_start_xmit) from [<809c6584>] (sch_direct_xmit+0xcc/0x264) r10:834e5600 r9:00000000 r8:00000000 r7:82b44000 r6:82ab1f00 r5:834e5600 r4:83f27400 | [<809c64b8>] (sch_direct_xmit) from [<809c6c0c>] (__qdisc_run+0x4f0/0x534) To fix this problem, only set skb ownership to sockets which have still a ref count > 0. Cc: Oliver Hartkopp <socketcan@hartkopp.net> Cc: Andre Naujoks <nautsch2@gmail.com> Suggested-by: Eric Dumazet <edumazet@google.com> Fixes: 0ae89beb283a ("can: add destructor for self generated skbs") Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> --- include/linux/can/skb.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)