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[SRU,H/I/OEM-5.10,1/1] io_uring: ensure symmetry in handling iter types in loop_rw_iter()

Message ID 20210920133342.13917-2-cascardo@canonical.com
State Accepted
Headers show
Series CVE-2021-41073 | expand

Commit Message

Thadeu Lima de Souza Cascardo Sept. 20, 2021, 1:33 p.m. UTC 
From: Jens Axboe <axboe@kernel.dk>

When setting up the next segment, we check what type the iter is and
handle it accordingly. However, when incrementing and processed amount
we do not, and both iter advance and addr/len are adjusted, regardless
of type. Split the increment side just like we do on the setup side.

Fixes: 4017eb91a9e7 ("io_uring: make loop_rw_iter() use original user supplied pointers")
Cc: stable@vger.kernel.org
Reported-by: Valentina Palmiotti <vpalmiotti@gmail.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit 16c8d2df7ec0eed31b7d3b61cb13206a7fb930cc)
CVE-2021-41073
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
---
 fs/io_uring.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

Comments

Stefan Bader Sept. 20, 2021, 1:43 p.m. UTC | #1 
On 20.09.21 15:33, Thadeu Lima de Souza Cascardo wrote:
> From: Jens Axboe <axboe@kernel.dk>
> 
> When setting up the next segment, we check what type the iter is and
> handle it accordingly. However, when incrementing and processed amount
> we do not, and both iter advance and addr/len are adjusted, regardless
> of type. Split the increment side just like we do on the setup side.
> 
> Fixes: 4017eb91a9e7 ("io_uring: make loop_rw_iter() use original user supplied pointers")
> Cc: stable@vger.kernel.org
> Reported-by: Valentina Palmiotti <vpalmiotti@gmail.com>
> Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> (cherry picked from commit 16c8d2df7ec0eed31b7d3b61cb13206a7fb930cc)
> CVE-2021-41073
> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
> ---
>   fs/io_uring.c | 9 ++++++---
>   1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index e1e1acc4be15..b4e9b68fe196 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -3309,12 +3309,15 @@ static ssize_t loop_rw_iter(int rw, struct io_kiocb *req, struct iov_iter *iter)
>   				ret = nr;
>   			break;
>   		}
> +		if (!iov_iter_is_bvec(iter)) {
> +			iov_iter_advance(iter, nr);
> +		} else {
> +			req->rw.len -= nr;
> +			req->rw.addr += nr;
> +		}
>   		ret += nr;
>   		if (nr != iovec.iov_len)
>   			break;
> -		req->rw.len -= nr;
> -		req->rw.addr += nr;
> -		iov_iter_advance(iter, nr);
>   	}
>   
>   	return ret;
>
diff mbox series

Patch

diff --git a/fs/io_uring.c b/fs/io_uring.c
index e1e1acc4be15..b4e9b68fe196 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -3309,12 +3309,15 @@  static ssize_t loop_rw_iter(int rw, struct io_kiocb *req, struct iov_iter *iter)
 				ret = nr;
 			break;
 		}
+		if (!iov_iter_is_bvec(iter)) {
+			iov_iter_advance(iter, nr);
+		} else {
+			req->rw.len -= nr;
+			req->rw.addr += nr;
+		}
 		ret += nr;
 		if (nr != iovec.iov_len)
 			break;
-		req->rw.len -= nr;
-		req->rw.addr += nr;
-		iov_iter_advance(iter, nr);
 	}
 
 	return ret;