On Fri, Jun 5, 2020 at 1:10 AM kernel test robot <rong.a.c...@intel.com> wrote:
>
> Greeting,
>
> FYI, we noticed the following commit (built with gcc-4.9):
>
> commit: a6211caa634da39d861a47437ffcda8b38ef421b ("net: revert "net: get rid
> of an signed integer overflow in ip_idents_reserve()"")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
>
> in testcase: boot
>
> on test machine: qemu-system-i386 -enable-kvm -cpu SandyBridge -smp 2 -m 8G
>
> caused below changes (please refer to attached dmesg/kmsg for entire
> log/backtrace):
>
>
>
>
> If you fix the issue, kindly add following tag
> Reported-by: kernel test robot <rong.a.c...@intel.com>
>
There you go.
We decided this was a bogus report, and that UBSAN requires sane compilers.
Please read the fine comment that was added in this commit and update
your compiler or do not mess with compiler flags.
+ /* If UBSAN reports an error there, please make sure your compiler
+ * supports -fno-strict-overflow before reporting it that was a bug
+ * in UBSAN, and it has been fixed in GCC-8.
+ */
+ return atomic_add_return(segs + delta, p_id) - segs;
Thanks.
>
> [ 35.019158]
> ================================================================================
> [ 35.019995] UBSAN: signed-integer-overflow in
> arch/x86/include/asm/atomic.h:167:2
> [ 35.020884] -1045826149 + -1341282523 cannot be represented in type 'int'
> [ 35.021544] CPU: 0 PID: 350 Comm: systemd-timesyn Tainted: G S
> 5.7.0-rc5-00221-ga6211caa634da #1
> [ 35.022550] Call Trace:
> [ 35.022812] dump_stack+0x16/0x26
> [ 35.023151] ubsan_epilogue+0x8/0x40
> [ 35.023526] handle_overflow+0x80/0xa0
> [ 35.023925] ? __ip_append_data+0x8ca/0xdd0
> [ 35.024408] __ubsan_handle_add_overflow+0xa/0x10
> [ 35.024872] ip_idents_reserve+0x79/0x90
> [ 35.025263] __ip_select_ident+0x48/0x70
> [ 35.025659] __ip_make_skb+0x32f/0x410
> [ 35.026039] ip_make_skb+0xa6/0xe0
> [ 35.026383] ? ip_reply_glue_bits+0x50/0x50
> [ 35.026770] ? ip_route_output_key_hash+0xb6/0xe0
> [ 35.027221] udp_sendmsg+0x577/0xba0
> [ 35.027551] ? ip_reply_glue_bits+0x50/0x50
> [ 35.027960] ? lock_release+0x9d/0x260
> [ 35.028328] inet_sendmsg+0x2e/0x50
> [ 35.028819] __sys_sendto+0xe2/0x130
> [ 35.029178] ? lock_acquire+0x92/0x310
> [ 35.029552] ? __might_fault+0x41/0x80
> [ 35.029903] ? find_held_lock+0x2d/0xd0
> [ 35.030262] ? lock_release+0x9d/0x260
> [ 35.030620] __ia32_sys_socketcall+0x141/0x240
> [ 35.031064] do_int80_syscall_32+0x46/0x3d0
> [ 35.031470] entry_INT80_32+0x113/0x113
> [ 35.031854] EIP: 0xb7f54a02
> [ 35.032133] Code: 95 01 00 05 25 36 02 00 83 ec 14 8d 80 e8 99 ff ff 50 6a
> 02 e8 1f ff 00 00 c7 04 24 7f 00 00 00 e8 7e 87 01 00 66 90 90 cd 80 <c3> 8d
> b6 00 00 00 00 8d bc 27 00 00 00 00 8b 1c 24 c3 8d b6 00 00
> [ 35.033938] EAX: ffffffda EBX: 0000000b ECX: bfecd7c8 EDX: 00000000
> [ 35.034562] ESI: b7cd3000 EDI: 00000000 EBP: 00000000 ESP: bfecd7bc
> [ 35.035199] DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b EFLAGS: 00000293
> [ 35.035865]
> ================================================================================
> [ OK ] Started OpenBSD Secure Shell server.
> [ OK ] Started LSB: Start and stop bmc-watchdog.
> [ OK ] Started LSB: Execute the kexec -e command to reboot system.
> [ OK ] Started Login Service.
> Starting Preprocess NFS configuration...
> [ OK ] Reached target Host and Network Name Lookups.
> Starting LSB: Load kernel image with kexec...
> [ OK ] Reached target Login Prompts.
> [ OK ] Started Preprocess NFS configuration.
> Starting Notify NFS peers of a restart...
> Starting NFS status monitor for NFSv2/3 locking....
> [ OK ] Started Notify NFS peers of a restart.
> [ OK ] Started LSB: Load kernel image with kexec.
> [ OK ] Started NFS status monitor for NFSv2/3 locking..
> [ 48.881188] sysrq: Emergency Sync
> [ 48.881750] sysrq: Resetting
>
>
> To reproduce:
>
> # build kernel
> cd linux
> cp config-5.7.0-rc5-00221-ga6211caa634da .config
> make HOSTCC=gcc-4.9 CC=gcc-4.9 ARCH=i386 olddefconfig prepare
> modules_prepare bzImage
>
> git clone https://github.com/intel/lkp-tests.git
> cd lkp-tests
> bin/lkp qemu -k <bzImage> job-script # job-script is attached in this
> email
>
>
>
> Thanks,
> Rong Chen
>
