Commit 85a58309 authored by Amir Mohammad Jahangirzad's avatar Amir Mohammad Jahangirzad Committed by Jens Axboe
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io_uring/cancel: validate opcode for IORING_ASYNC_CANCEL_OP 



io_async_cancel_prep() reads the opcode selector from sqe->len and
stores it in cancel->opcode, which is an 8-bit field. Since sqe->len
is a 32-bit value, values larger than U8_MAX are implicitly truncated.

This can cause unintended opcode matches when the truncated value
corresponds to a valid io_uring opcode. For example, submitting a value
such as 0x10b will be truncated to 0x0b (IORING_OP_TIMEOUT), allowing a
cancel request to match operations it did not intend to target.
Validate the opcode value before assigning it to the 8-bit field and
reject values outside the valid io_uring opcode range.

Signed-off-by: default avatarAmir Mohammad Jahangirzad <a.jahangirzad@gmail.com>
Link: https://patch.msgid.link/20260331232113.615972-1-a.jahangirzad@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 19a8cc6c

io_uring/cancel.c

+8 −1
Original line number Diff line number Diff line
@@ -156,9 +156,16 @@ int io_async_cancel_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) 
		cancel->fd = READ_ONCE(sqe->fd);

	}

	if (cancel->flags & IORING_ASYNC_CANCEL_OP) {

		u32 op;



		if (cancel->flags & IORING_ASYNC_CANCEL_ANY)

			return -EINVAL;

		cancel->opcode = READ_ONCE(sqe->len);



		op = READ_ONCE(sqe->len);

		if (op >= IORING_OP_LAST)

			return -EINVAL;



		cancel->opcode = op;

	}



	return 0;