| Message ID | 20240403130908.93421-1-edumazet@google.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | d313eb8b77557a6d5855f42d2234bd592c7b50dd |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] net/sched: act_skbmod: prevent kernel-infoleak | expand |
On Wed, Apr 3, 2024 at 9:09 AM Eric Dumazet <edumazet@google.com> wrote: > > syzbot found that tcf_skbmod_dump() was copying four bytes > from kernel stack to user space [1]. > > The issue here is that 'struct tc_skbmod' has a four bytes hole. > > We need to clear the structure before filling fields. > > [1] > BUG: KMSAN: kernel-infoleak in instrument_copy_to_user include/linux/instrumented.h:114 [inline] > BUG: KMSAN: kernel-infoleak in copy_to_user_iter lib/iov_iter.c:24 [inline] > BUG: KMSAN: kernel-infoleak in iterate_ubuf include/linux/iov_iter.h:29 [inline] > BUG: KMSAN: kernel-infoleak in iterate_and_advance2 include/linux/iov_iter.h:245 [inline] > BUG: KMSAN: kernel-infoleak in iterate_and_advance include/linux/iov_iter.h:271 [inline] > BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x366/0x2520 lib/iov_iter.c:185 > instrument_copy_to_user include/linux/instrumented.h:114 [inline] > copy_to_user_iter lib/iov_iter.c:24 [inline] > iterate_ubuf include/linux/iov_iter.h:29 [inline] > iterate_and_advance2 include/linux/iov_iter.h:245 [inline] > iterate_and_advance include/linux/iov_iter.h:271 [inline] > _copy_to_iter+0x366/0x2520 lib/iov_iter.c:185 > copy_to_iter include/linux/uio.h:196 [inline] > simple_copy_to_iter net/core/datagram.c:532 [inline] > __skb_datagram_iter+0x185/0x1000 net/core/datagram.c:420 > skb_copy_datagram_iter+0x5c/0x200 net/core/datagram.c:546 > skb_copy_datagram_msg include/linux/skbuff.h:4050 [inline] > netlink_recvmsg+0x432/0x1610 net/netlink/af_netlink.c:1962 > sock_recvmsg_nosec net/socket.c:1046 [inline] > sock_recvmsg+0x2c4/0x340 net/socket.c:1068 > __sys_recvfrom+0x35a/0x5f0 net/socket.c:2242 > __do_sys_recvfrom net/socket.c:2260 [inline] > __se_sys_recvfrom net/socket.c:2256 [inline] > __x64_sys_recvfrom+0x126/0x1d0 net/socket.c:2256 > do_syscall_64+0xd5/0x1f0 > entry_SYSCALL_64_after_hwframe+0x6d/0x75 > > Uninit was stored to memory at: > pskb_expand_head+0x30f/0x19d0 net/core/skbuff.c:2253 > netlink_trim+0x2c2/0x330 net/netlink/af_netlink.c:1317 > netlink_unicast+0x9f/0x1260 net/netlink/af_netlink.c:1351 > nlmsg_unicast include/net/netlink.h:1144 [inline] > nlmsg_notify+0x21d/0x2f0 net/netlink/af_netlink.c:2610 > rtnetlink_send+0x73/0x90 net/core/rtnetlink.c:741 > rtnetlink_maybe_send include/linux/rtnetlink.h:17 [inline] > tcf_add_notify net/sched/act_api.c:2048 [inline] > tcf_action_add net/sched/act_api.c:2071 [inline] > tc_ctl_action+0x146e/0x19d0 net/sched/act_api.c:2119 > rtnetlink_rcv_msg+0x1737/0x1900 net/core/rtnetlink.c:6595 > netlink_rcv_skb+0x375/0x650 net/netlink/af_netlink.c:2559 > rtnetlink_rcv+0x34/0x40 net/core/rtnetlink.c:6613 > netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline] > netlink_unicast+0xf4c/0x1260 net/netlink/af_netlink.c:1361 > netlink_sendmsg+0x10df/0x11f0 net/netlink/af_netlink.c:1905 > sock_sendmsg_nosec net/socket.c:730 [inline] > __sock_sendmsg+0x30f/0x380 net/socket.c:745 > ____sys_sendmsg+0x877/0xb60 net/socket.c:2584 > ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638 > __sys_sendmsg net/socket.c:2667 [inline] > __do_sys_sendmsg net/socket.c:2676 [inline] > __se_sys_sendmsg net/socket.c:2674 [inline] > __x64_sys_sendmsg+0x307/0x4a0 net/socket.c:2674 > do_syscall_64+0xd5/0x1f0 > entry_SYSCALL_64_after_hwframe+0x6d/0x75 > > Uninit was stored to memory at: > __nla_put lib/nlattr.c:1041 [inline] > nla_put+0x1c6/0x230 lib/nlattr.c:1099 > tcf_skbmod_dump+0x23f/0xc20 net/sched/act_skbmod.c:256 > tcf_action_dump_old net/sched/act_api.c:1191 [inline] > tcf_action_dump_1+0x85e/0x970 net/sched/act_api.c:1227 > tcf_action_dump+0x1fd/0x460 net/sched/act_api.c:1251 > tca_get_fill+0x519/0x7a0 net/sched/act_api.c:1628 > tcf_add_notify_msg net/sched/act_api.c:2023 [inline] > tcf_add_notify net/sched/act_api.c:2042 [inline] > tcf_action_add net/sched/act_api.c:2071 [inline] > tc_ctl_action+0x1365/0x19d0 net/sched/act_api.c:2119 > rtnetlink_rcv_msg+0x1737/0x1900 net/core/rtnetlink.c:6595 > netlink_rcv_skb+0x375/0x650 net/netlink/af_netlink.c:2559 > rtnetlink_rcv+0x34/0x40 net/core/rtnetlink.c:6613 > netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline] > netlink_unicast+0xf4c/0x1260 net/netlink/af_netlink.c:1361 > netlink_sendmsg+0x10df/0x11f0 net/netlink/af_netlink.c:1905 > sock_sendmsg_nosec net/socket.c:730 [inline] > __sock_sendmsg+0x30f/0x380 net/socket.c:745 > ____sys_sendmsg+0x877/0xb60 net/socket.c:2584 > ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638 > __sys_sendmsg net/socket.c:2667 [inline] > __do_sys_sendmsg net/socket.c:2676 [inline] > __se_sys_sendmsg net/socket.c:2674 [inline] > __x64_sys_sendmsg+0x307/0x4a0 net/socket.c:2674 > do_syscall_64+0xd5/0x1f0 > entry_SYSCALL_64_after_hwframe+0x6d/0x75 > > Local variable opt created at: > tcf_skbmod_dump+0x9d/0xc20 net/sched/act_skbmod.c:244 > tcf_action_dump_old net/sched/act_api.c:1191 [inline] > tcf_action_dump_1+0x85e/0x970 net/sched/act_api.c:1227 > > Bytes 188-191 of 248 are uninitialized > Memory access of size 248 starts at ffff888117697680 > Data copied to user address 00007ffe56d855f0 > > Fixes: 86da71b57383 ("net_sched: Introduce skbmod action") > Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> cheers, jamal > --- > net/sched/act_skbmod.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/net/sched/act_skbmod.c b/net/sched/act_skbmod.c > index 39945b139c4817584fb9803b9e65c89fef68eca0..cd0accaf844a18e4a6a626adba5fae05df66b0a3 100644 > --- a/net/sched/act_skbmod.c > +++ b/net/sched/act_skbmod.c > @@ -241,13 +241,13 @@ static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a, > struct tcf_skbmod *d = to_skbmod(a); > unsigned char *b = skb_tail_pointer(skb); > struct tcf_skbmod_params *p; > - struct tc_skbmod opt = { > - .index = d->tcf_index, > - .refcnt = refcount_read(&d->tcf_refcnt) - ref, > - .bindcnt = atomic_read(&d->tcf_bindcnt) - bind, > - }; > + struct tc_skbmod opt; > struct tcf_t t; > > + memset(&opt, 0, sizeof(opt)); > + opt.index = d->tcf_index; > + opt.refcnt = refcount_read(&d->tcf_refcnt) - ref, > + opt.bindcnt = atomic_read(&d->tcf_bindcnt) - bind; > spin_lock_bh(&d->tcf_lock); > opt.action = d->tcf_action; > p = rcu_dereference_protected(d->skbmod_p, > -- > 2.44.0.478.gd926399ef9-goog >
Hello: This patch was applied to netdev/net.git (main) by Jakub Kicinski <kuba@kernel.org>: On Wed, 3 Apr 2024 13:09:08 +0000 you wrote: > syzbot found that tcf_skbmod_dump() was copying four bytes > from kernel stack to user space [1]. > > The issue here is that 'struct tc_skbmod' has a four bytes hole. > > We need to clear the structure before filling fields. > > [...] Here is the summary with links: - [net] net/sched: act_skbmod: prevent kernel-infoleak https://git.kernel.org/netdev/net/c/d313eb8b7755 You are awesome, thank you!
diff --git a/net/sched/act_skbmod.c b/net/sched/act_skbmod.c index 39945b139c4817584fb9803b9e65c89fef68eca0..cd0accaf844a18e4a6a626adba5fae05df66b0a3 100644 --- a/net/sched/act_skbmod.c +++ b/net/sched/act_skbmod.c @@ -241,13 +241,13 @@ static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a, struct tcf_skbmod *d = to_skbmod(a); unsigned char *b = skb_tail_pointer(skb); struct tcf_skbmod_params *p; - struct tc_skbmod opt = { - .index = d->tcf_index, - .refcnt = refcount_read(&d->tcf_refcnt) - ref, - .bindcnt = atomic_read(&d->tcf_bindcnt) - bind, - }; + struct tc_skbmod opt; struct tcf_t t; + memset(&opt, 0, sizeof(opt)); + opt.index = d->tcf_index; + opt.refcnt = refcount_read(&d->tcf_refcnt) - ref, + opt.bindcnt = atomic_read(&d->tcf_bindcnt) - bind; spin_lock_bh(&d->tcf_lock); opt.action = d->tcf_action; p = rcu_dereference_protected(d->skbmod_p,
syzbot found that tcf_skbmod_dump() was copying four bytes from kernel stack to user space [1]. The issue here is that 'struct tc_skbmod' has a four bytes hole. We need to clear the structure before filling fields. [1] BUG: KMSAN: kernel-infoleak in instrument_copy_to_user include/linux/instrumented.h:114 [inline] BUG: KMSAN: kernel-infoleak in copy_to_user_iter lib/iov_iter.c:24 [inline] BUG: KMSAN: kernel-infoleak in iterate_ubuf include/linux/iov_iter.h:29 [inline] BUG: KMSAN: kernel-infoleak in iterate_and_advance2 include/linux/iov_iter.h:245 [inline] BUG: KMSAN: kernel-infoleak in iterate_and_advance include/linux/iov_iter.h:271 [inline] BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x366/0x2520 lib/iov_iter.c:185 instrument_copy_to_user include/linux/instrumented.h:114 [inline] copy_to_user_iter lib/iov_iter.c:24 [inline] iterate_ubuf include/linux/iov_iter.h:29 [inline] iterate_and_advance2 include/linux/iov_iter.h:245 [inline] iterate_and_advance include/linux/iov_iter.h:271 [inline] _copy_to_iter+0x366/0x2520 lib/iov_iter.c:185 copy_to_iter include/linux/uio.h:196 [inline] simple_copy_to_iter net/core/datagram.c:532 [inline] __skb_datagram_iter+0x185/0x1000 net/core/datagram.c:420 skb_copy_datagram_iter+0x5c/0x200 net/core/datagram.c:546 skb_copy_datagram_msg include/linux/skbuff.h:4050 [inline] netlink_recvmsg+0x432/0x1610 net/netlink/af_netlink.c:1962 sock_recvmsg_nosec net/socket.c:1046 [inline] sock_recvmsg+0x2c4/0x340 net/socket.c:1068 __sys_recvfrom+0x35a/0x5f0 net/socket.c:2242 __do_sys_recvfrom net/socket.c:2260 [inline] __se_sys_recvfrom net/socket.c:2256 [inline] __x64_sys_recvfrom+0x126/0x1d0 net/socket.c:2256 do_syscall_64+0xd5/0x1f0 entry_SYSCALL_64_after_hwframe+0x6d/0x75 Uninit was stored to memory at: pskb_expand_head+0x30f/0x19d0 net/core/skbuff.c:2253 netlink_trim+0x2c2/0x330 net/netlink/af_netlink.c:1317 netlink_unicast+0x9f/0x1260 net/netlink/af_netlink.c:1351 nlmsg_unicast include/net/netlink.h:1144 [inline] nlmsg_notify+0x21d/0x2f0 net/netlink/af_netlink.c:2610 rtnetlink_send+0x73/0x90 net/core/rtnetlink.c:741 rtnetlink_maybe_send include/linux/rtnetlink.h:17 [inline] tcf_add_notify net/sched/act_api.c:2048 [inline] tcf_action_add net/sched/act_api.c:2071 [inline] tc_ctl_action+0x146e/0x19d0 net/sched/act_api.c:2119 rtnetlink_rcv_msg+0x1737/0x1900 net/core/rtnetlink.c:6595 netlink_rcv_skb+0x375/0x650 net/netlink/af_netlink.c:2559 rtnetlink_rcv+0x34/0x40 net/core/rtnetlink.c:6613 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline] netlink_unicast+0xf4c/0x1260 net/netlink/af_netlink.c:1361 netlink_sendmsg+0x10df/0x11f0 net/netlink/af_netlink.c:1905 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x30f/0x380 net/socket.c:745 ____sys_sendmsg+0x877/0xb60 net/socket.c:2584 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638 __sys_sendmsg net/socket.c:2667 [inline] __do_sys_sendmsg net/socket.c:2676 [inline] __se_sys_sendmsg net/socket.c:2674 [inline] __x64_sys_sendmsg+0x307/0x4a0 net/socket.c:2674 do_syscall_64+0xd5/0x1f0 entry_SYSCALL_64_after_hwframe+0x6d/0x75 Uninit was stored to memory at: __nla_put lib/nlattr.c:1041 [inline] nla_put+0x1c6/0x230 lib/nlattr.c:1099 tcf_skbmod_dump+0x23f/0xc20 net/sched/act_skbmod.c:256 tcf_action_dump_old net/sched/act_api.c:1191 [inline] tcf_action_dump_1+0x85e/0x970 net/sched/act_api.c:1227 tcf_action_dump+0x1fd/0x460 net/sched/act_api.c:1251 tca_get_fill+0x519/0x7a0 net/sched/act_api.c:1628 tcf_add_notify_msg net/sched/act_api.c:2023 [inline] tcf_add_notify net/sched/act_api.c:2042 [inline] tcf_action_add net/sched/act_api.c:2071 [inline] tc_ctl_action+0x1365/0x19d0 net/sched/act_api.c:2119 rtnetlink_rcv_msg+0x1737/0x1900 net/core/rtnetlink.c:6595 netlink_rcv_skb+0x375/0x650 net/netlink/af_netlink.c:2559 rtnetlink_rcv+0x34/0x40 net/core/rtnetlink.c:6613 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline] netlink_unicast+0xf4c/0x1260 net/netlink/af_netlink.c:1361 netlink_sendmsg+0x10df/0x11f0 net/netlink/af_netlink.c:1905 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x30f/0x380 net/socket.c:745 ____sys_sendmsg+0x877/0xb60 net/socket.c:2584 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638 __sys_sendmsg net/socket.c:2667 [inline] __do_sys_sendmsg net/socket.c:2676 [inline] __se_sys_sendmsg net/socket.c:2674 [inline] __x64_sys_sendmsg+0x307/0x4a0 net/socket.c:2674 do_syscall_64+0xd5/0x1f0 entry_SYSCALL_64_after_hwframe+0x6d/0x75 Local variable opt created at: tcf_skbmod_dump+0x9d/0xc20 net/sched/act_skbmod.c:244 tcf_action_dump_old net/sched/act_api.c:1191 [inline] tcf_action_dump_1+0x85e/0x970 net/sched/act_api.c:1227 Bytes 188-191 of 248 are uninitialized Memory access of size 248 starts at ffff888117697680 Data copied to user address 00007ffe56d855f0 Fixes: 86da71b57383 ("net_sched: Introduce skbmod action") Signed-off-by: Eric Dumazet <edumazet@google.com> --- net/sched/act_skbmod.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)