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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 101b7a97143a Merge tag 'acpi-6.10-rc1' of git://git.kernel..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15633df4980000
kernel config: https://syzkaller.appspot.com/x/.config?x=7ac2f8c387a23814
dashboard link: https://syzkaller.appspot.com/bug?extid=0c85cae3350b7d486aee
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/4f673334a91c/disk-101b7a97.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8e6db59f4091/vmlinux-101b7a97.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7e5782387c9d/bzImage-101b7a97.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0c85ca...@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: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+0x366/0x24b0 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+0x366/0x24b0 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:4070 [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_recvmsg+0x18a/0x620 net/socket.c:2803
___sys_recvmsg+0x223/0x840 net/socket.c:2845
__sys_recvmsg net/socket.c:2875 [inline]
__do_sys_recvmsg net/socket.c:2885 [inline]
__se_sys_recvmsg net/socket.c:2882 [inline]
__x64_sys_recvmsg+0x304/0x4a0 net/socket.c:2882
x64_sys_call+0x38ff/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:48
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was stored to memory at:
pskb_expand_head+0x30f/0x19d0 net/core/skbuff.c:2271
netlink_trim+0x2c2/0x330 net/netlink/af_netlink.c:1317
netlink_broadcast_filtered+0x82/0x23b0 net/netlink/af_netlink.c:1523
nlmsg_multicast_filtered include/net/netlink.h:1111 [inline]
nlmsg_multicast include/net/netlink.h:1130 [inline]
nlmsg_notify+0x15f/0x2f0 net/netlink/af_netlink.c:2602
rtnl_notify+0xc3/0xf0 net/core/rtnetlink.c:757
wireless_nlevent_flush net/wireless/wext-core.c:354 [inline]
wireless_nlevent_process+0xfe/0x250 net/wireless/wext-core.c:414
process_one_work kernel/workqueue.c:3267 [inline]
process_scheduled_works+0xa81/0x1bd0 kernel/workqueue.c:3348
worker_thread+0xea5/0x1560 kernel/workqueue.c:3429
kthread+0x3e2/0x540 kernel/kthread.c:389
ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Uninit was stored to memory at:
wireless_send_event+0x566/0x1020 net/wireless/wext-core.c:580
ioctl_standard_iw_point+0x12e5/0x13c0
compat_standard_call+0x179/0x310 net/wireless/wext-core.c:1110
wext_ioctl_dispatch+0x234/0xa30 net/wireless/wext-core.c:1016
compat_wext_handle_ioctl+0x1ae/0x2f0 net/wireless/wext-core.c:1139
compat_sock_ioctl+0x26b/0x1370 net/socket.c:3525
__do_compat_sys_ioctl fs/ioctl.c:1004 [inline]
__se_compat_sys_ioctl+0x791/0x1090 fs/ioctl.c:947
__ia32_compat_sys_ioctl+0x93/0xe0 fs/ioctl.c:947
ia32_sys_call+0x1481/0x40a0 arch/x86/include/generated/asm/syscalls_32.h:55
do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
__do_fast_syscall_32+0xb4/0x120 arch/x86/entry/common.c:386
do_fast_syscall_32+0x38/0x80 arch/x86/entry/common.c:411
do_SYSENTER_32+0x1f/0x30 arch/x86/entry/common.c:449
entry_SYSENTER_compat_after_hwframe+0x84/0x8e

Local variable iwp created at:
compat_standard_call+0x48/0x310 net/wireless/wext-core.c:1097
wext_ioctl_dispatch+0x234/0xa30 net/wireless/wext-core.c:1016

Bytes 60-63 of 64 are uninitialized
Memory access of size 64 starts at ffff88804af03180
Data copied to user address 00007fff5690c968

CPU: 0 PID: 4697 Comm: dhcpcd Tainted: G W 6.9.0-syzkaller-02339-g101b7a97143a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
=====================================================


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