* [PATCH] io_uring: fix sporadic -EFAULT from IORING_OP_RECMSG
@ 2019-12-15 17:57 Jens Axboe
0 siblings, 0 replies; only message in thread
From: Jens Axboe @ 2019-12-15 17:57 UTC (permalink / raw)
To: io-uring; +Cc: 李通洲
If we have to punt the recvmsg to async context, we copy all the
context. But since the iovec used can be either on-stack (if small) or
dynamically allocated, if it's on-stack, then we need to ensure we reset
the iov pointer. If we don't, then we're reusing old stack data, and
that can lead to -EFAULTs if things get overwritten.
Ensure we retain the right pointers for the iov, and free it as well if
we end up having to go beyond UIO_FASTIOV number of vectors.
Fixes: 03b1230ca12a ("io_uring: ensure async punted sendmsg/recvmsg requests copy data")
Reported-by: 李通洲 <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
---
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 2fff83a3878f..4424c5d7a3a1 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2041,6 +2041,7 @@ static int io_sendmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
struct io_kiocb **nxt, bool force_nonblock)
{
#if defined(CONFIG_NET)
+ struct io_async_msghdr *kmsg = NULL;
struct socket *sock;
int ret;
@@ -2051,7 +2052,6 @@ static int io_sendmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
if (sock) {
struct io_async_ctx io, *copy;
struct sockaddr_storage addr;
- struct msghdr *kmsg;
unsigned flags;
flags = READ_ONCE(sqe->msg_flags);
@@ -2061,17 +2061,21 @@ static int io_sendmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
flags |= MSG_DONTWAIT;
if (req->io) {
- kmsg = &req->io->msg.msg;
- kmsg->msg_name = &addr;
+ kmsg = &req->io->msg;
+ kmsg->msg.msg_name = &addr;
+ /* if iov is set, it's allocated already */
+ if (!req->io->msg.iov)
+ req->io->msg.iov = req->io->msg.fast_iov;
+ kmsg->msg.msg_iter.iov = req->io->msg.iov;
} else {
- kmsg = &io.msg.msg;
- kmsg->msg_name = &addr;
+ kmsg = &io.msg;
+ kmsg->msg.msg_name = &addr;
ret = io_sendmsg_prep(req, &io);
if (ret)
goto out;
}
- ret = __sys_sendmsg_sock(sock, kmsg, flags);
+ ret = __sys_sendmsg_sock(sock, &kmsg->msg, flags);
if (force_nonblock && ret == -EAGAIN) {
copy = kmalloc(sizeof(*copy), GFP_KERNEL);
if (!copy) {
@@ -2089,6 +2093,8 @@ static int io_sendmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
}
out:
+ if (kmsg && kmsg->iov != kmsg->fast_iov)
+ kfree(kmsg->iov);
io_cqring_add_event(req, ret);
if (ret < 0)
req_set_fail_links(req);
@@ -2120,6 +2126,7 @@ static int io_recvmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
struct io_kiocb **nxt, bool force_nonblock)
{
#if defined(CONFIG_NET)
+ struct io_async_msghdr *kmsg = NULL;
struct socket *sock;
int ret;
@@ -2131,7 +2138,6 @@ static int io_recvmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
struct user_msghdr __user *msg;
struct io_async_ctx io, *copy;
struct sockaddr_storage addr;
- struct msghdr *kmsg;
unsigned flags;
flags = READ_ONCE(sqe->msg_flags);
@@ -2143,17 +2149,21 @@ static int io_recvmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
msg = (struct user_msghdr __user *) (unsigned long)
READ_ONCE(sqe->addr);
if (req->io) {
- kmsg = &req->io->msg.msg;
- kmsg->msg_name = &addr;
+ kmsg = &req->io->msg;
+ kmsg->msg.msg_name = &addr;
+ /* if iov is set, it's allocated already */
+ if (!req->io->msg.iov)
+ req->io->msg.iov = req->io->msg.fast_iov;
+ kmsg->msg.msg_iter.iov = req->io->msg.iov;
} else {
- kmsg = &io.msg.msg;
- kmsg->msg_name = &addr;
+ kmsg = &io.msg;
+ kmsg->msg.msg_name = &addr;
ret = io_recvmsg_prep(req, &io);
if (ret)
goto out;
}
- ret = __sys_recvmsg_sock(sock, kmsg, msg, io.msg.uaddr, flags);
+ ret = __sys_recvmsg_sock(sock, &kmsg->msg, msg, kmsg->uaddr, flags);
if (force_nonblock && ret == -EAGAIN) {
copy = kmalloc(sizeof(*copy), GFP_KERNEL);
if (!copy) {
@@ -2171,6 +2181,8 @@ static int io_recvmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
}
out:
+ if (kmsg && kmsg->iov != kmsg->fast_iov)
+ kfree(kmsg->iov);
io_cqring_add_event(req, ret);
if (ret < 0)
req_set_fail_links(req);
--
Jens Axboe
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