RDMA/mlx5: Protect from shift operand overflow

Ensure that user didn't supply values too large that can cause overflow.

UBSAN: Undefined behaviour in drivers/infiniband/hw/mlx5/qp.c:263:23
shift exponent -2147483648 is negative
CPU: 0 PID: 292 Comm: syzkaller612609 Not tainted 4.16.0-rc1+ #131
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.0-0-g63451fca13-prebuilt.qemu-project.org 04/01/2014 Call
Trace:
dump_stack+0xde/0x164
ubsan_epilogue+0xe/0x81
set_rq_size+0x7c2/0xa90
create_qp_common+0xc18/0x43c0
mlx5_ib_create_qp+0x379/0x1ca0
create_qp.isra.5+0xc94/0x2260
ib_uverbs_create_qp+0x21b/0x2a0
ib_uverbs_write+0xc2c/0x1010
vfs_write+0x1b0/0x550
SyS_write+0xc7/0x1a0
do_syscall_64+0x1aa/0x740
entry_SYSCALL_64_after_hwframe+0x26/0x9b
RIP: 0033:0x433569
RSP: 002b:00007ffc6e62f448 EFLAGS: 00000217 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00000000004002f8 RCX: 0000000000433569
RDX: 0000000000000070 RSI: 00000000200042c0 RDI: 0000000000000003
RBP: 00000000006d5018 R08: 00000000004002f8 R09: 00000000004002f8
R10: 00000000004002f8 R11: 0000000000000217 R12: 0000000000000000
R13: 000000000040c9f0 R14: 000000000040ca80 R15: 0000000000000006

Cc: <stable@vger.kernel.org> # 3.10
Fixes: e126ba97 ("mlx5: Add driver for Mellanox Connect-IB adapters")
Cc: syzkaller <syzkaller@googlegroups.com>
Reported-by: Noa Osherovich <noaos@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/mlx5/qp.c

@@ -259,7 +259,11 @@ static int set_rq_size(struct mlx5_ib_dev *dev, struct ib_qp_cap *cap,
 	} else {
 		if (ucmd) {
 			qp->rq.wqe_cnt = ucmd->rq_wqe_count;
+			if (ucmd->rq_wqe_shift > BITS_PER_BYTE * sizeof(ucmd->rq_wqe_shift))
+				return -EINVAL;
 			qp->rq.wqe_shift = ucmd->rq_wqe_shift;
+			if ((1 << qp->rq.wqe_shift) / sizeof(struct mlx5_wqe_data_seg) < qp->wq_sig)
+				return -EINVAL;
 			qp->rq.max_gs = (1 << qp->rq.wqe_shift) / sizeof(struct mlx5_wqe_data_seg) - qp->wq_sig;
 			qp->rq.max_post = qp->rq.wqe_cnt;
 		} else {