Re: [syzbot] [net?] KMSAN: kernel-infoleak in __skb_datagram_iter (4)

[syzbot <syzbot+0c85cae3350b7d486aee@syzkaller.appspotmail.com>]

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@syzkaller.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
=====================================================


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