Re: 4.6.0-rc3 UBSAN: atomic.h:156:2,Apr 14 15:40:24 n22kvm-clone kernel: signed integer overflow:

[Toralf FÃrster]

Toralf FÃrster:
> Got this at a 32 bit KVM during boot :
and later while fuzzying with trinity :


Apr 14 15:44:56 n22kvm-clone kernel: ================================================================================
Apr 14 15:44:56 n22kvm-clone kernel: UBSAN: Undefined behaviour in ./arch/x86/include/asm/futex.h:53:13
Apr 14 15:44:56 n22kvm-clone kernel: shift exponent -1 is negative
Apr 14 15:44:56 n22kvm-clone kernel: CPU: 0 PID: 13969 Comm: trinity-c1 Not tainted 4.6.0-rc3 #5
Apr 14 15:44:56 n22kvm-clone kernel: Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.8.2-0-g33fbe13 by qemu-project.org 04/01/2014
Apr 14 15:44:56 n22kvm-clone kernel:  00000000 00000086 f3e7fde8 d6fe2fe8 00000007 f3e7fe14 d78b8dac f3e7fdf8
Apr 14 15:44:56 n22kvm-clone kernel:  d704887e f3e7fdf8 d78b8dac f3e7fe78 d704919d d774876c f3e7fe18 00000002
Apr 14 15:44:56 n22kvm-clone kernel:  f3e16180 00000001 00000286 d600312d f3e7fe5c 00000286 00000000 00000001
Apr 14 15:44:56 n22kvm-clone kernel: Call Trace:
Apr 14 15:44:56 n22kvm-clone kernel:  [<d6fe2fe8>] dump_stack+0x9f/0xe7
Apr 14 15:44:56 n22kvm-clone kernel:  [<d704887e>] ubsan_epilogue+0xe/0x40
Apr 14 15:44:56 n22kvm-clone kernel:  [<d704919d>] __ubsan_handle_shift_out_of_bounds+0xdd/0x140
Apr 14 15:44:56 n22kvm-clone kernel:  [<d6ba2257>] ? do_futex+0x257/0xdc0
Apr 14 15:44:56 n22kvm-clone kernel:  [<d75bf3ad>] ? _raw_spin_lock_nested+0x3d/0x50
Apr 14 15:44:56 n22kvm-clone kernel:  [<d6ba2a04>] do_futex+0xa04/0xdc0
Apr 14 15:44:56 n22kvm-clone kernel:  [<d75bfb0f>] ? _raw_spin_unlock_irqrestore+0x5f/0x80
Apr 14 15:44:56 n22kvm-clone kernel:  [<d6ba2e44>] SyS_futex+0x84/0x150
Apr 14 15:44:56 n22kvm-clone kernel:  [<d6a033b0>] do_fast_syscall_32+0x150/0x960
Apr 14 15:44:56 n22kvm-clone kernel:  [<d6ba2dc0>] ? do_futex+0xdc0/0xdc0
Apr 14 15:44:56 n22kvm-clone kernel:  [<d75bfeeb>] sysenter_past_esp+0x4c/0x7f
Apr 14 15:44:56 n22kvm-clone kernel: ================================================================================


-- 
Toralf
PGP: C4EACDDE 0076E94E, OTR: 420E74C8 30246EE7