linux-kernel - [PATCH 3/4] io_uring: verify resv is 0 in ringfd register/unregister

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Date:   Tue, 12 Apr 2022 09:30:41 -0700
From:   Dylan Yudaken <dylany@...com>
To:     <io-uring@...r.kernel.org>
CC:     <axboe@...nel.dk>, <asml.silence@...il.com>,
        <linux-kernel@...r.kernel.org>, <kernel-team@...com>,
        Dylan Yudaken <dylany@...com>
Subject: [PATCH 3/4] io_uring: verify resv is 0 in ringfd register/unregister

Only allow resv field to be 0 in struct io_uring_rsrc_update user
arguments.

Fixes: e7a6c00dc77a ("io_uring: add support for registering ring file descriptors")
Signed-off-by: Dylan Yudaken <dylany@...com>
---
 fs/io_uring.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index e899192ffb77..a84bfec97d0d 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -10533,6 +10533,11 @@ static int io_ringfd_register(struct io_ring_ctx *ctx, void __user *__arg,
 			break;
 		}
 
+		if (reg.resv) {
+			ret = -EINVAL;
+			break;
+		}
+
 		if (reg.offset == -1U) {
 			start = 0;
 			end = IO_RINGFD_REG_MAX;
@@ -10579,7 +10584,7 @@ static int io_ringfd_unregister(struct io_ring_ctx *ctx, void __user *__arg,
 			ret = -EFAULT;
 			break;
 		}
-		if (reg.offset >= IO_RINGFD_REG_MAX) {
+		if (reg.resv || reg.offset >= IO_RINGFD_REG_MAX) {
 			ret = -EINVAL;
 			break;
 		}
-- 
2.30.2