Re: [PATCH -next] io_uring: Fix undefined-behaviour in io_issue_sqe

[yebin <yebin10@huawei.com>]

On 2021/11/18 9:59, Ye Bin wrote:
> We got issue as follows:
> ================================================================================
> UBSAN: Undefined behaviour in ./include/linux/ktime.h:42:14
> signed integer overflow:
> -4966321760114568020 * 1000000000 cannot be represented in type 'long long int'
> CPU: 1 PID: 2186 Comm: syz-executor.2 Not tainted 4.19.90+ #12
> Hardware name: linux,dummy-virt (DT)
> Call trace:
>   dump_backtrace+0x0/0x3f0 arch/arm64/kernel/time.c:78
>   show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158
>   __dump_stack lib/dump_stack.c:77 [inline]
>   dump_stack+0x170/0x1dc lib/dump_stack.c:118
>   ubsan_epilogue+0x18/0xb4 lib/ubsan.c:161
>   handle_overflow+0x188/0x1dc lib/ubsan.c:192
>   __ubsan_handle_mul_overflow+0x34/0x44 lib/ubsan.c:213
>   ktime_set include/linux/ktime.h:42 [inline]
>   timespec64_to_ktime include/linux/ktime.h:78 [inline]
>   io_timeout fs/io_uring.c:5153 [inline]
>   io_issue_sqe+0x42c8/0x4550 fs/io_uring.c:5599
>   __io_queue_sqe+0x1b0/0xbc0 fs/io_uring.c:5988
>   io_queue_sqe+0x1ac/0x248 fs/io_uring.c:6067
>   io_submit_sqe fs/io_uring.c:6137 [inline]
>   io_submit_sqes+0xed8/0x1c88 fs/io_uring.c:6331
>   __do_sys_io_uring_enter fs/io_uring.c:8170 [inline]
>   __se_sys_io_uring_enter fs/io_uring.c:8129 [inline]
>   __arm64_sys_io_uring_enter+0x490/0x980 fs/io_uring.c:8129
>   invoke_syscall arch/arm64/kernel/syscall.c:53 [inline]
>   el0_svc_common+0x374/0x570 arch/arm64/kernel/syscall.c:121
>   el0_svc_handler+0x190/0x260 arch/arm64/kernel/syscall.c:190
>   el0_svc+0x10/0x218 arch/arm64/kernel/entry.S:1017
> ================================================================================
>
> As ktime_set only judge 'secs' if big than KTIME_SEC_MAX, but if we pass
> negative value maybe lead to overflow.
> To address this issue, we must check if 'sec' is negative.
>
> Signed-off-by: Ye Bin <yebin10@huawei.com>
> ---
>   fs/io_uring.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index f9e720595860..d8a6446a7921 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -6157,6 +6157,9 @@ static int io_timeout_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe,
>   	if (get_timespec64(&data->ts, u64_to_user_ptr(sqe->addr)))
>   		return -EFAULT;
>   
> +	if (data->ts.tv_sec < 0 || data->ts.tv_nsec < 0)
> +		return -EINVAL;
> +
>   	data->mode = io_translate_timeout_mode(flags);
>   	hrtimer_init(&data->timer, io_timeout_get_clock(data), data->mode);
>   
ping...