Message-ID: <CANn89iJptb2gackja+KocyPYwf855EgZM34GSO3km4Z8tcwq1w@mail.gmail.com>
Date: Wed, 6 Nov 2024 19:09:18 +0100
From: Eric Dumazet <edumazet@...gle.com>
To: syzbot <syzbot+0c85cae3350b7d486aee@...kaller.appspotmail.com>
Cc: davem@...emloft.net, horms@...nel.org, kuba@...nel.org, 
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org, pabeni@...hat.com, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [net?] KMSAN: kernel-infoleak in __skb_datagram_iter (4)

On Wed, Nov 6, 2024 at 6:58 PM syzbot
<syzbot+0c85cae3350b7d486aee@...kaller.appspotmail.com> wrote:
>
> syzbot has found a reproducer for the following issue on:
>
> HEAD commit:    2e1b3cc9d7f7 Merge tag 'arm-fixes-6.12-2' of git://git.ker..
> git tree:       upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=1485dd5f980000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=6fdf74cce377223b
> dashboard link: https://syzkaller.appspot.com/bug?extid=0c85cae3350b7d486aee
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1685dd5f980000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10bfb6a7980000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/08456e37db58/disk-2e1b3cc9.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/cc957f7ba80b/vmlinux-2e1b3cc9.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/7579fe72ed89/bzImage-2e1b3cc9.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+0c85cae3350b7d486aee@...kaller.appspotmail.com
>
> =====================================================
> 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:30 [inline]
> BUG: KMSAN: kernel-infoleak in iterate_and_advance2 include/linux/iov_iter.h:300 [inline]
> BUG: KMSAN: kernel-infoleak in iterate_and_advance include/linux/iov_iter.h:328 [inline]
> BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x2f3/0x2b30 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:30 [inline]
>  iterate_and_advance2 include/linux/iov_iter.h:300 [inline]
>  iterate_and_advance include/linux/iov_iter.h:328 [inline]
>  _copy_to_iter+0x2f3/0x2b30 lib/iov_iter.c:185
>  copy_to_iter include/linux/uio.h:211 [inline]
>  simple_copy_to_iter net/core/datagram.c:524 [inline]
>  __skb_datagram_iter+0x18d/0x1190 net/core/datagram.c:401
>  skb_copy_datagram_iter+0x5c/0x200 net/core/datagram.c:538
>  skb_copy_datagram_msg include/linux/skbuff.h:4076 [inline]
>  netlink_recvmsg+0x432/0x1610 net/netlink/af_netlink.c:1958
>  sock_recvmsg_nosec net/socket.c:1051 [inline]
>  sock_recvmsg+0x2c4/0x340 net/socket.c:1073
>  sock_read_iter+0x32d/0x3c0 net/socket.c:1143
>  io_iter_do_read io_uring/rw.c:771 [inline]
>  __io_read+0x8d2/0x20f0 io_uring/rw.c:865
>  io_read+0x3e/0xf0 io_uring/rw.c:943
>  io_issue_sqe+0x429/0x22c0 io_uring/io_uring.c:1739
>  io_queue_sqe io_uring/io_uring.c:1953 [inline]
>  io_req_task_submit+0x104/0x1e0 io_uring/io_uring.c:1373
>  io_poll_task_func+0x12e5/0x1620
>  io_handle_tw_list+0x23a/0x5c0 io_uring/io_uring.c:1063
>  tctx_task_work_run+0xf8/0x3d0 io_uring/io_uring.c:1135
>  tctx_task_work+0x6d/0xc0 io_uring/io_uring.c:1153
>  task_work_run+0x268/0x310 kernel/task_work.c:239
>  ptrace_notify+0x304/0x320 kernel/signal.c:2403
>  ptrace_report_syscall include/linux/ptrace.h:415 [inline]
>  ptrace_report_syscall_exit include/linux/ptrace.h:477 [inline]
>  syscall_exit_work+0x14e/0x3e0 kernel/entry/common.c:173
>  syscall_exit_to_user_mode_prepare kernel/entry/common.c:200 [inline]
>  __syscall_exit_to_user_mode_work kernel/entry/common.c:205 [inline]
>  syscall_exit_to_user_mode+0x13b/0x170 kernel/entry/common.c:218
>  do_syscall_64+0xda/0x1e0 arch/x86/entry/common.c:89
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> Uninit was stored to memory at:
>  pskb_expand_head+0x305/0x1a60 net/core/skbuff.c:2283
>  netlink_trim+0x2c2/0x330 net/netlink/af_netlink.c:1313
>  netlink_unicast+0x9f/0x1260 net/netlink/af_netlink.c:1347
>  nlmsg_unicast include/net/netlink.h:1158 [inline]
>  nlmsg_notify+0x21d/0x2f0 net/netlink/af_netlink.c:2602
>  rtnetlink_send+0x73/0x90 net/core/rtnetlink.c:770
>  rtnetlink_maybe_send include/linux/rtnetlink.h:18 [inline]
>  tcf_add_notify net/sched/act_api.c:2068 [inline]
>  tcf_action_add net/sched/act_api.c:2091 [inline]
>  tc_ctl_action+0x146e/0x19d0 net/sched/act_api.c:2139
>  rtnetlink_rcv_msg+0x12fc/0x1410 net/core/rtnetlink.c:6675
>  netlink_rcv_skb+0x375/0x650 net/netlink/af_netlink.c:2551
>  rtnetlink_rcv+0x34/0x40 net/core/rtnetlink.c:6693
>  netlink_unicast_kernel net/netlink/af_netlink.c:1331 [inline]
>  netlink_unicast+0xf52/0x1260 net/netlink/af_netlink.c:1357
>  netlink_sendmsg+0x10da/0x11e0 net/netlink/af_netlink.c:1901
>  sock_sendmsg_nosec net/socket.c:729 [inline]
>  __sock_sendmsg+0x30f/0x380 net/socket.c:744
>  ____sys_sendmsg+0x877/0xb60 net/socket.c:2607
>  ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2661
>  __sys_sendmsg net/socket.c:2690 [inline]
>  __do_sys_sendmsg net/socket.c:2699 [inline]
>  __se_sys_sendmsg net/socket.c:2697 [inline]
>  __x64_sys_sendmsg+0x300/0x4a0 net/socket.c:2697
>  x64_sys_call+0x2da0/0x3ba0 arch/x86/include/generated/asm/syscalls_64.h:47
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> Uninit was stored to memory at:
>  __nla_put lib/nlattr.c:1041 [inline]
>  nla_put+0x1c6/0x230 lib/nlattr.c:1099
>  tcf_ife_dump+0x250/0x10b0 net/sched/act_ife.c:660
>  tcf_action_dump_old net/sched/act_api.c:1190 [inline]
>  tcf_action_dump_1+0x85e/0x970 net/sched/act_api.c:1226
>  tcf_action_dump+0x1fd/0x460 net/sched/act_api.c:1250
>  tca_get_fill+0x519/0x7a0 net/sched/act_api.c:1648
>  tcf_add_notify_msg net/sched/act_api.c:2043 [inline]
>  tcf_add_notify net/sched/act_api.c:2062 [inline]
>  tcf_action_add net/sched/act_api.c:2091 [inline]
>  tc_ctl_action+0x1365/0x19d0 net/sched/act_api.c:2139
>  rtnetlink_rcv_msg+0x12fc/0x1410 net/core/rtnetlink.c:6675
>  netlink_rcv_skb+0x375/0x650 net/netlink/af_netlink.c:2551
>  rtnetlink_rcv+0x34/0x40 net/core/rtnetlink.c:6693
>  netlink_unicast_kernel net/netlink/af_netlink.c:1331 [inline]
>  netlink_unicast+0xf52/0x1260 net/netlink/af_netlink.c:1357
>  netlink_sendmsg+0x10da/0x11e0 net/netlink/af_netlink.c:1901
>  sock_sendmsg_nosec net/socket.c:729 [inline]
>  __sock_sendmsg+0x30f/0x380 net/socket.c:744
>  ____sys_sendmsg+0x877/0xb60 net/socket.c:2607
>  ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2661
>  __sys_sendmsg net/socket.c:2690 [inline]
>  __do_sys_sendmsg net/socket.c:2699 [inline]
>  __se_sys_sendmsg net/socket.c:2697 [inline]
>  __x64_sys_sendmsg+0x300/0x4a0 net/socket.c:2697
>  x64_sys_call+0x2da0/0x3ba0 arch/x86/include/generated/asm/syscalls_64.h:47
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> Local variable opt created at:
>  tcf_ife_dump+0xab/0x10b0 net/sched/act_ife.c:647
>  tcf_action_dump_old net/sched/act_api.c:1190 [inline]
>  tcf_action_dump_1+0x85e/0x970 net/sched/act_api.c:1226
>
> Bytes 158-159 of 216 are uninitialized
> Memory access of size 216 starts at ffff88811980e280
>
> CPU: 1 UID: 0 PID: 5791 Comm: syz-executor190 Not tainted 6.12.0-rc6-syzkaller-00077-g2e1b3cc9d7f7 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
> =====================================================
>
>
> ---
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.

#syz test

diff --git a/include/uapi/linux/tc_act/tc_connmark.h
b/include/uapi/linux/tc_act/tc_connmark.h
index 9f8f6f709feb5cb67decc5fc80c422d9373df930..7089b9466065df074f98b47ffe179baf386600a9
100644
--- a/include/uapi/linux/tc_act/tc_connmark.h
+++ b/include/uapi/linux/tc_act/tc_connmark.h
@@ -8,6 +8,7 @@
 struct tc_connmark {
        tc_gen;
        __u16 zone;
+       __u16 pad;
 };

 enum {
diff --git a/include/uapi/linux/tc_act/tc_ife.h
b/include/uapi/linux/tc_act/tc_ife.h
index 8c401f185675582febc262a8d11bf9598cb8a1f4..6f7f7af20fe9466631cc571f9c00665489cfe91d
100644
--- a/include/uapi/linux/tc_act/tc_ife.h
+++ b/include/uapi/linux/tc_act/tc_ife.h
@@ -13,6 +13,7 @@
 struct tc_ife {
        tc_gen;
        __u16 flags;
+       __u16 pad;
 };

 /*XXX: We need to encode the total number of bytes consumed */
diff --git a/include/uapi/linux/tc_act/tc_pedit.h
b/include/uapi/linux/tc_act/tc_pedit.h
index f5cab7fc96ab1ea1516beeedff20b279c3cfa4d7..28e026dbc1400899a072fdbac6872654bea3ab8d
100644
--- a/include/uapi/linux/tc_act/tc_pedit.h
+++ b/include/uapi/linux/tc_act/tc_pedit.h
@@ -62,6 +62,7 @@ struct tc_pedit_sel {
        tc_gen;
        unsigned char           nkeys;
        unsigned char           flags;
+       __u16                                   pad;
        struct tc_pedit_key     keys[] __counted_by(nkeys);
 };

Powered by blists - more mailing lists