linux-kernel - [PATCH][next][V2] io_uring: Fix premature return from loop and memory leak

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Date:   Thu, 29 Apr 2021 11:46:02 +0100
From:   Colin King <colin.king@...onical.com>
To:     Jens Axboe <axboe@...nel.dk>,
        Pavel Begunkov <asml.silence@...il.com>,
        io-uring@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH][next][V2] io_uring: Fix premature return from loop and memory leak

From: Colin Ian King <colin.king@...onical.com>

Currently the -EINVAL error return path is leaking memory allocated
to data. Fix this by not returning immediately but instead setting
the error return variable to -EINVAL and breaking out of the loop.

Kudos to Pavel Begunkov for suggesting a correct fix.

Signed-off-by: Colin Ian King <colin.king@...onical.com>
---

V2: set ret/err to -EINVAL and break rather than kfree and return,
    fix both occurrences of this issue.

---
 fs/io_uring.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 47c2f126f885..c783ad83f220 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8417,8 +8417,10 @@ static int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
 		ret = io_buffer_validate(&iov);
 		if (ret)
 			break;
-		if (!iov.iov_base && tag)
-			return -EINVAL;
+		if (!iov.iov_base && tag) {
+			ret = -EINVAL;
+			break;
+		}
 
 		ret = io_sqe_buffer_register(ctx, &iov, &ctx->user_bufs[i],
 					     &last_hpage);
@@ -8468,8 +8470,10 @@ static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
 		err = io_buffer_validate(&iov);
 		if (err)
 			break;
-		if (!iov.iov_base && tag)
-			return -EINVAL;
+		if (!iov.iov_base && tag) {
+			err = -EINVAL;
+			break;
+		}
 		err = io_sqe_buffer_register(ctx, &iov, &imu, &last_hpage);
 		if (err)
 			break;
-- 
2.30.2