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io_uring/rsrc: ensure compat iovecs are copied correctly

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For buffer registration (or updates), a userspace iovec is copied in
and updated. If the application is within a compat syscall, then the
iovec type is compat_iovec rather than iovec. However, the type used
in __io_sqe_buffers_update() and io_sqe_buffers_register() is always
struct iovec, and hence the source is incremented by the size of a
non-compat iovec in the loop. This misses every other iovec in the
source, and will run into garbage half way through the copies and
return -EFAULT to the application.

Maintain the source address separately and assign to our user vec
pointer, so that copies always happen from the right source address.

While in there, correct a bad placement of __user which triggered
the following sparse warning prior to this fix:

io_uring/rsrc.c:981:33: warning: cast removes address space '__user' of expression
io_uring/rsrc.c:981:30: warning: incorrect type in assignment (different address spaces)
io_uring/rsrc.c:981:30:    expected struct iovec const [noderef] __user *uvec
io_uring/rsrc.c:981:30:    got struct iovec *[noderef] __user

Fixes: f4eaf8eda8 ("io_uring/rsrc: Drop io_copy_iov in favor of iovec API")
Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2024-08-28 09:42:33 -06:00
parent e0ee967630
commit 1c47c0d601
1 changed files with 15 additions and 4 deletions
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19
io_uring/rsrc.c
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@ -394,10 +394,11 @@ static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
struct io_uring_rsrc_update2 *up,
unsigned int nr_args)
{
struct iovec __user *uvec = u64_to_user_ptr(up->data);
u64 __user *tags = u64_to_user_ptr(up->tags);
struct iovec fast_iov, *iov;
struct page *last_hpage = NULL;
struct iovec __user *uvec;
u64 user_data = up->data;
__u32 done;
int i, err;
@ -410,7 +411,8 @@ static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
struct io_mapped_ubuf *imu;
u64 tag = 0;
iov = iovec_from_user(&uvec[done], 1, 1, &fast_iov, ctx->compat);
uvec = u64_to_user_ptr(user_data);
iov = iovec_from_user(uvec, 1, 1, &fast_iov, ctx->compat);
if (IS_ERR(iov)) {
err = PTR_ERR(iov);
break;
@ -443,6 +445,10 @@ static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
ctx->user_bufs[i] = imu;
*io_get_tag_slot(ctx->buf_data, i) = tag;
if (ctx->compat)
user_data += sizeof(struct compat_iovec);
else
user_data += sizeof(struct iovec);
}
return done ? done : err;
}
@ -949,7 +955,7 @@ int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
struct page *last_hpage = NULL;
struct io_rsrc_data *data;
struct iovec fast_iov, *iov = &fast_iov;
const struct iovec __user *uvec = (struct iovec * __user) arg;
const struct iovec __user *uvec;
int i, ret;
BUILD_BUG_ON(IORING_MAX_REG_BUFFERS >= (1u << 16));
@ -972,7 +978,8 @@ int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
for (i = 0; i < nr_args; i++, ctx->nr_user_bufs++) {
if (arg) {
iov = iovec_from_user(&uvec[i], 1, 1, &fast_iov, ctx->compat);
uvec = (struct iovec __user *) arg;
iov = iovec_from_user(uvec, 1, 1, &fast_iov, ctx->compat);
if (IS_ERR(iov)) {
ret = PTR_ERR(iov);
break;
@ -980,6 +987,10 @@ int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
ret = io_buffer_validate(iov);
if (ret)
break;
if (ctx->compat)
arg += sizeof(struct compat_iovec);
else
arg += sizeof(struct iovec);
}
if (!iov->iov_base && *io_get_tag_slot(data, i)) {