net: mptcp: cap forward allocation to 1M
the following syzkaller reproducer:
r0 = socket$inet_mptcp(0x2, 0x1, 0x106)
bind$inet(r0, &(0x7f0000000080)={0x2, 0x4e24, @multicast2}, 0x10)
connect$inet(r0, &(0x7f0000000480)={0x2, 0x4e24, @local}, 0x10)
sendto$inet(r0, &(0x7f0000000100)="f6", 0xffffffe7, 0xc000, 0x0, 0x0)
systematically triggers the following warning:
WARNING: CPU: 2 PID: 8618 at net/core/stream.c:208 sk_stream_kill_queues+0x3fa/0x580
Modules linked in:
CPU: 2 PID: 8618 Comm: syz-executor Not tainted 5.10.0+ #334
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.1-4.module+el8.1.0+4066+0f1aadab 04/04
RIP: 0010:sk_stream_kill_queues+0x3fa/0x580
Code: df 48 c1 ea 03 0f b6 04 02 84 c0 74 04 3c 03 7e 40 8b ab 20 02 00 00 e9 64 ff ff ff e8 df f0 81 2
RSP: 0018:ffffc9000290fcb0 EFLAGS: 00010293
RAX: ffff888011cb8000 RBX: 0000000000000000 RCX: ffffffff86eecf0e
RDX: 0000000000000000 RSI: ffffffff86eecf6a RDI: 0000000000000005
RBP: 0000000000000e28 R08: ffff888011cb8000 R09: fffffbfff1f48139
R10: ffffffff8fa409c7 R11: fffffbfff1f48138 R12: ffff8880215e6220
R13: ffffffff8fa409c0 R14: ffffc9000290fd30 R15: 1ffff92000521fa2
FS: 00007f41c78f4800(0000) GS:ffff88802d000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f95c803d088 CR3: 0000000025ed2000 CR4: 00000000000006f0
Call Trace:
__mptcp_destroy_sock+0x4f5/0x8e0
mptcp_close+0x5e2/0x7f0
inet_release+0x12b/0x270
__sock_release+0xc8/0x270
sock_close+0x18/0x20
__fput+0x272/0x8e0
task_work_run+0xe0/0x1a0
exit_to_user_mode_prepare+0x1df/0x200
syscall_exit_to_user_mode+0x19/0x50
entry_SYSCALL_64_after_hwframe+0x44/0xa9
userspace programs provide arbitrarily high values of 'len' in sendmsg():
this is causing integer overflow of 'amount'. Cap forward allocation to 1
megabyte: higher values are not really useful.
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Fixes: e93da92896 ("mptcp: implement wmem reservation")
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Link: https://lore.kernel.org/r/3334d00d8b2faecafdfab9aa593efcbf61442756.1608584474.git.dcaratti@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
e7579d5d5b