[PATCH v2 3/3] RDMA/mlx5: Fix shift overflow in mlx5_ib_create_wq

[Kees Cook]

From: Leon Romanovsky <leonro@xxxxxxxxxxxx>

[   61.182439] UBSAN: Undefined behaviour in drivers/infiniband/hw/mlx5/qp.c:5366:34
[   61.183673] shift exponent 4294967288 is too large for 32-bit type 'unsigned int'
[   61.185530] CPU: 0 PID: 639 Comm: qp Not tainted 4.18.0-rc1-00037-g4aa1d69a9c60-dirty #96
[   61.186981] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-2.fc27 04/01/2014
[   61.188315] Call Trace:
[   61.188661]  dump_stack+0xc7/0x13b
[   61.190427]  ubsan_epilogue+0x9/0x49
[   61.190899]  __ubsan_handle_shift_out_of_bounds+0x1ea/0x22f
[   61.197040]  mlx5_ib_create_wq+0x1c99/0x1d50
[   61.206632]  ib_uverbs_ex_create_wq+0x499/0x820
[   61.213892]  ib_uverbs_write+0x77e/0xae0
[   61.248018]  vfs_write+0x121/0x3b0
[   61.249831]  ksys_write+0xa1/0x120
[   61.254024]  do_syscall_64+0x7c/0x2a0
[   61.256178]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[   61.259211] RIP: 0033:0x7f54bab70e99
[   61.262125] Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89
[   61.268678] RSP: 002b:00007ffe1541c318 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[   61.271076] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f54bab70e99
[   61.273795] RDX: 0000000000000070 RSI: 0000000020000240 RDI: 0000000000000003
[   61.276982] RBP: 00007ffe1541c330 R08: 00000000200078e0 R09: 0000000000000002
[   61.280035] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004005c0
[   61.283279] R13: 00007ffe1541c420 R14: 0000000000000000 R15: 0000000000000000

Cc: <stable@xxxxxxxxxxxxxxx> # 4.7
Fixes: 79b20a6c3014 ("IB/mlx5: Add receive Work Queue verbs")
Cc: syzkaller <syzkaller@xxxxxxxxxxxxxxxx>
Reported-by: Noa Osherovich <noaos@xxxxxxxxxxxx>
Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 drivers/infiniband/hw/mlx5/qp.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/mlx5/qp.c b/drivers/infiniband/hw/mlx5/qp.c
index a4f1f638509f..7fc156db643d 100644
--- a/drivers/infiniband/hw/mlx5/qp.c
+++ b/drivers/infiniband/hw/mlx5/qp.c
@@ -5365,7 +5365,10 @@ static int set_user_rq_size(struct mlx5_ib_dev *dev,
 
 	rwq->wqe_count = ucmd->rq_wqe_count;
 	rwq->wqe_shift = ucmd->rq_wqe_shift;
-	rwq->buf_size = (rwq->wqe_count << rwq->wqe_shift);
+	if (check_shift_overflow(rwq->wqe_count, rwq->wqe_shift,
+				 &rwq->buf_size))
+		return -EINVAL;
+
 	rwq->log_rq_stride = rwq->wqe_shift;
 	rwq->log_rq_size = ilog2(rwq->wqe_count);
 	return 0;
-- 
2.17.1