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: Amir Mohammad Jahangirzad --- io_uring/cancel.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/io_uring/cancel.c b/io_uring/cancel.c index 65e04063e..5e5eb9cfc 100644 --- a/io_uring/cancel.c +++ b/io_uring/cancel.c @@ -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; -- 2.53.0