From: Pavel Begunkov <asml.silence@gmail.com>
Date: Sun, 29 Nov 2020 18:33:32 +0000 (+0000)
Subject: io_uring: fix recvmsg setup with compat buf-select
X-Git-Tag: v5.10-rc7~13^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2d280bc8930ba9ed1705cfd548c6c8924949eaf1;p=thirdparty%2Fkernel%2Flinux.git

io_uring: fix recvmsg setup with compat buf-select

__io_compat_recvmsg_copy_hdr() with REQ_F_BUFFER_SELECT reads out iov
len but never assigns it to iov/fast_iov, leaving sr->len with garbage.
Hopefully, following io_buffer_select() truncates it to the selected
buffer size, but the value is still may be under what was specified.

Cc: <stable@vger.kernel.org> # 5.7
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 1023f7b44ceaa..a2a7c65a77aa9 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4499,7 +4499,8 @@ static int __io_compat_recvmsg_copy_hdr(struct io_kiocb *req,
 			return -EFAULT;
 		if (clen < 0)
 			return -EINVAL;
-		sr->len = iomsg->iov[0].iov_len;
+		sr->len = clen;
+		iomsg->iov[0].iov_len = clen;
 		iomsg->iov = NULL;
 	} else {
 		ret = __import_iovec(READ, (struct iovec __user *)uiov, len,