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io_uring: handle -EFAULT properly in io_uring_setup()

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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: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Xiaoguang Wang 2020-05-05 16:28:53 +08:00 committed by Jens Axboe
parent d8f1b9716c
commit 7f13657d14
1 changed files with 11 additions and 13 deletions
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24
fs/io_uring.c
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@ -7760,7 +7760,8 @@ static int io_uring_get_fd(struct io_ring_ctx *ctx)
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 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p)
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,