Commit 7f13657d authored by Xiaoguang Wang's avatar Xiaoguang Wang Committed by Jens Axboe
Browse files

io_uring: handle -EFAULT properly in io_uring_setup() 



If copy_to_user() in io_uring_setup() failed, we'll leak many kernel
resources, which will be recycled until process terminates. This bug
can be reproduced by using mprotect to set params to PROT_READ. To fix
this issue, refactor io_uring_create() a bit to add a new 'struct
io_uring_params __user *params' parameter and move the copy_to_user()
in io_uring_setup() to io_uring_setup(), if copy_to_user() failed,
we can free kernel resource properly.

Suggested-by: default avatarJens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent d8f1b971

fs/io_uring.c

+11 −13
Original line number Diff line number Diff line
@@ -7760,7 +7760,8 @@ err: 
	return ret;

}



static int io_uring_create(unsigned entries, struct io_uring_params *p)

static int io_uring_create(unsigned entries, struct io_uring_params *p,

			   struct io_uring_params __user *params)

{

	struct user_struct *user = NULL;

	struct io_ring_ctx *ctx;
@@ -7852,6 +7853,14 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p) 
	p->cq_off.overflow = offsetof(struct io_rings, cq_overflow);

	p->cq_off.cqes = offsetof(struct io_rings, cqes);



	p->features = IORING_FEAT_SINGLE_MMAP | IORING_FEAT_NODROP |

			IORING_FEAT_SUBMIT_STABLE | IORING_FEAT_RW_CUR_POS |

			IORING_FEAT_CUR_PERSONALITY | IORING_FEAT_FAST_POLL;



	if (copy_to_user(params, p, sizeof(*p))) {

		ret = -EFAULT;

		goto err;

	}

	/*

	 * Install ring fd as the very last thing, so we don't risk someone

	 * having closed it before we finish setup
@@ -7860,9 +7869,6 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p) 
	if (ret < 0)

		goto err;



	p->features = IORING_FEAT_SINGLE_MMAP | IORING_FEAT_NODROP |

			IORING_FEAT_SUBMIT_STABLE | IORING_FEAT_RW_CUR_POS |

			IORING_FEAT_CUR_PERSONALITY | IORING_FEAT_FAST_POLL;

	trace_io_uring_create(ret, ctx, p->sq_entries, p->cq_entries, p->flags);

	return ret;

err:
@@ -7878,7 +7884,6 @@ err: 
static long io_uring_setup(u32 entries, struct io_uring_params __user *params)

{

	struct io_uring_params p;

	long ret;

	int i;



	if (copy_from_user(&p, params, sizeof(p)))
@@ -7893,14 +7898,7 @@ static long io_uring_setup(u32 entries, struct io_uring_params __user *params) 
			IORING_SETUP_CLAMP | IORING_SETUP_ATTACH_WQ))

		return -EINVAL;



	ret = io_uring_create(entries, &p);

	if (ret < 0)

		return ret;



	if (copy_to_user(params, &p, sizeof(p)))

		return -EFAULT;



	return ret;

	return  io_uring_create(entries, &p, params);

}



SYSCALL_DEFINE2(io_uring_setup, u32, entries,

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