linux-kernel - [PATCH -next] io_uring: Fix undefined-behaviour in io_issue

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Message-ID: <20211118015907.844807-1-yebin10@huawei.com>
Date:   Thu, 18 Nov 2021 09:59:07 +0800
From:   Ye Bin <yebin10@...wei.com>
To:     <axboe@...nel.dk>, <asml.silence@...il.com>,
        <io-uring@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     Ye Bin <yebin10@...wei.com>
Subject: [PATCH -next] io_uring: Fix undefined-behaviour in io_issue_sqe

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@...wei.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);
 
-- 
2.31.1