io_uring: check for overflows in io_pin_pages

WARNING: CPU: 0 PID: 5834 at io_uring/memmap.c:144 io_pin_pages+0x149/0x180 io_uring/memmap.c:144
CPU: 0 UID: 0 PID: 5834 Comm: syz-executor825 Not tainted 6.12.0-next-20241118-syzkaller #0
Call Trace:
 <TASK>
 __io_uaddr_map+0xfb/0x2d0 io_uring/memmap.c:183
 io_rings_map io_uring/io_uring.c:2611 [inline]
 io_allocate_scq_urings+0x1c0/0x650 io_uring/io_uring.c:3470
 io_uring_create+0x5b5/0xc00 io_uring/io_uring.c:3692
 io_uring_setup io_uring/io_uring.c:3781 [inline]
 ...
 </TASK>

io_pin_pages()'s uaddr parameter came directly from the user and can be
garbage. Don't just add size to it as it can overflow.

Cc: stable@vger.kernel.org
Reported-by:  <syzbot+2159cbb522b02847c053@syzkaller.appspotmail.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1b7520ddb168e1d537d64be47414a0629d0d8f8f.1732581026.git.asml.silence@gmail.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>