Commit 75769e3f authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
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io_uring: improve import_fixed overflow checks 



Replace a hand-coded overflow check with a specialised function. Even
though compilers are smart enough to generate identical binary (i.e.
check carry bit), but it's more foolproof and conveys the intention
better.

Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e437dcdc929bacbb6f11a4824ecbbf17225cb82a.1617287883.git.asml.silence@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 0aec38fd

fs/io_uring.c

+3 −4
Original line number Diff line number Diff line
@@ -2785,8 +2785,8 @@ static int io_import_fixed(struct io_kiocb *req, int rw, struct iov_iter *iter) 
	size_t len = req->rw.len;

	struct io_mapped_ubuf *imu;

	u16 index, buf_index = req->buf_index;

	u64 buf_end, buf_addr = req->rw.addr;

	size_t offset;

	u64 buf_addr;



	if (unlikely(buf_index >= ctx->nr_user_bufs))

		return -EFAULT;
@@ -2794,11 +2794,10 @@ static int io_import_fixed(struct io_kiocb *req, int rw, struct iov_iter *iter) 
	imu = &ctx->user_bufs[index];

	buf_addr = req->rw.addr;



	/* overflow */

	if (buf_addr + len < buf_addr)

	if (unlikely(check_add_overflow(buf_addr, (u64)len, &buf_end)))

		return -EFAULT;

	/* not inside the mapped region */

	if (buf_addr < imu->ubuf || buf_addr + len > imu->ubuf + imu->len)

	if (buf_addr < imu->ubuf || buf_end > imu->ubuf + imu->len)

		return -EFAULT;



	/*