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From:   Kyungtae Kim <kt0755@gmail.com>
Date:   Sat, 12 Jan 2019 14:25:51 -0500
Message-ID: <CAEAjamvf8LzpRauFhxeh-EGY_ttqeds6_UQwikc5sm7ORKdjjw@mail.gmail.com>
Subject: UBSAN: Undefined behaviour in net/can/bcm.c
To:     socketcan@hartkopp.net, mkl@pengutronix.de, davem@davemloft.net
Cc:     Byoungyoung Lee <lifeasageek@gmail.com>,
        DaeRyong Jeong <threeearcat@gmail.com>,
        syzkaller@googlegroups.com, linux-can@vger.kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
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Sender: linux-kernel-owner@vger.kernel.org
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We report a bug in linux-4.19.13: "UBSAN: Undefined behaviour in net/can/bcm.c"

kernel config: https://kt0755.github.io/etc/config_4.19.13
repro: https://kt0755.github.io/etc/repro.296b5.c

An integer overflow arose in bcm_timeval_to_ktime() when
tv.tv_usec * NSEC_PER_USEC is larger than its boundary of the
destination (i.e., long).
To fix, an appropriate boundary check should be placed right before the usage.

=========================================
UBSAN: Undefined behaviour in net/can/bcm.c:140:41
signed integer overflow:
60870466536963773 * 1000 cannot be represented in type 'long int'
CPU: 0 PID: 7063 Comm: syz-executor3 Not tainted 4.19.13 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0xd2/0x148 lib/dump_stack.c:113
 ubsan_epilogue+0x12/0x94 lib/ubsan.c:159
 handle_overflow+0x1cf/0x21a lib/ubsan.c:190
 __ubsan_handle_mul_overflow+0x2a/0x35 lib/ubsan.c:214
 bcm_timeval_to_ktime net/can/bcm.c:140 [inline]
 bcm_rx_setup net/can/bcm.c:1190 [inline]
 bcm_sendmsg+0x3807/0x3fd0 net/can/bcm.c:1355
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg+0xdd/0x130 net/socket.c:631
 sock_write_iter+0x24b/0x3d0 net/socket.c:900
 call_write_iter include/linux/fs.h:1811 [inline]
 new_sync_write fs/read_write.c:474 [inline]
 __vfs_write+0x538/0x6e0 fs/read_write.c:487
 vfs_write+0x1b3/0x520 fs/read_write.c:549
 ksys_write+0xde/0x1c0 fs/read_write.c:598
 __do_sys_write fs/read_write.c:610 [inline]
 __se_sys_write fs/read_write.c:607 [inline]
 __x64_sys_write+0x7e/0xc0 fs/read_write.c:607
 do_syscall_64+0xc4/0x510 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4497b9
Code: e8 8c 9f 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48
89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d
01 f0 ff ff 0f 83 9b 6b fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fc2e6feac68 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fc2e6feb6cc RCX: 00000000004497b9
RDX: 0000000000000048 RSI: 00000000200000c0 RDI: 0000000000000013
RBP: 000000000071bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000ba60 R14: 00000000006f4b00 R15: 00007fc2e6feb700
=========================================

Thanks,
Kyungtae Kim