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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Cc: Jens Axboe <axboe@kernel.dk>,
	syzbot+f8e9a371388aa62ecab4@syzkaller.appspotmail.com,
	Sasha Levin <sashal@kernel.org>,
	io-uring@vger.kernel.org
Subject: [PATCH AUTOSEL 6.8 22/28] io_uring: clear opcode specific data for an early failure
Date: Wed,  3 Apr 2024 13:16:24 -0400
Message-ID: <20240403171656.335224-22-sashal@kernel.org>
In-Reply-To: <20240403171656.335224-1-sashal@kernel.org>
References: <20240403171656.335224-1-sashal@kernel.org>
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From: Jens Axboe <axboe@kernel.dk>

[ Upstream commit e21e1c45e1fe2e31732f40256b49c04e76a17cee ]

If failure happens before the opcode prep handler is called, ensure that
we clear the opcode specific area of the request, which holds data
specific to that request type. This prevents errors where opcode
handlers either don't get to clear per-request private data since prep
isn't even called.

Reported-and-tested-by: syzbot+f8e9a371388aa62ecab4@syzkaller.appspotmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 io_uring/io_uring.c | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index cd9a137ad6cef..42e27ad5fd828 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2159,6 +2159,13 @@ static void io_init_req_drain(struct io_kiocb *req)
 	}
 }
 
+static __cold int io_init_fail_req(struct io_kiocb *req, int err)
+{
+	/* ensure per-opcode data is cleared if we fail before prep */
+	memset(&req->cmd.data, 0, sizeof(req->cmd.data));
+	return err;
+}
+
 static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
 		       const struct io_uring_sqe *sqe)
 	__must_hold(&ctx->uring_lock)
@@ -2179,29 +2186,29 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
 
 	if (unlikely(opcode >= IORING_OP_LAST)) {
 		req->opcode = 0;
-		return -EINVAL;
+		return io_init_fail_req(req, -EINVAL);
 	}
 	def = &io_issue_defs[opcode];
 	if (unlikely(sqe_flags & ~SQE_COMMON_FLAGS)) {
 		/* enforce forwards compatibility on users */
 		if (sqe_flags & ~SQE_VALID_FLAGS)
-			return -EINVAL;
+			return io_init_fail_req(req, -EINVAL);
 		if (sqe_flags & IOSQE_BUFFER_SELECT) {
 			if (!def->buffer_select)
-				return -EOPNOTSUPP;
+				return io_init_fail_req(req, -EOPNOTSUPP);
 			req->buf_index = READ_ONCE(sqe->buf_group);
 		}
 		if (sqe_flags & IOSQE_CQE_SKIP_SUCCESS)
 			ctx->drain_disabled = true;
 		if (sqe_flags & IOSQE_IO_DRAIN) {
 			if (ctx->drain_disabled)
-				return -EOPNOTSUPP;
+				return io_init_fail_req(req, -EOPNOTSUPP);
 			io_init_req_drain(req);
 		}
 	}
 	if (unlikely(ctx->restricted || ctx->drain_active || ctx->drain_next)) {
 		if (ctx->restricted && !io_check_restriction(ctx, req, sqe_flags))
-			return -EACCES;
+			return io_init_fail_req(req, -EACCES);
 		/* knock it to the slow queue path, will be drained there */
 		if (ctx->drain_active)
 			req->flags |= REQ_F_FORCE_ASYNC;
@@ -2214,9 +2221,9 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
 	}
 
 	if (!def->ioprio && sqe->ioprio)
-		return -EINVAL;
+		return io_init_fail_req(req, -EINVAL);
 	if (!def->iopoll && (ctx->flags & IORING_SETUP_IOPOLL))
-		return -EINVAL;
+		return io_init_fail_req(req, -EINVAL);
 
 	if (def->needs_file) {
 		struct io_submit_state *state = &ctx->submit_state;
@@ -2240,12 +2247,12 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
 
 		req->creds = xa_load(&ctx->personalities, personality);
 		if (!req->creds)
-			return -EINVAL;
+			return io_init_fail_req(req, -EINVAL);
 		get_cred(req->creds);
 		ret = security_uring_override_creds(req->creds);
 		if (ret) {
 			put_cred(req->creds);
-			return ret;
+			return io_init_fail_req(req, ret);
 		}
 		req->flags |= REQ_F_CREDS;
 	}
-- 
2.43.0