Re: NULL ptr deref in perf/filter_match

[Peter Zijlstra]

On Thu, Aug 04, 2016 at 05:55:30PM +0200, Vegard Nossum wrote:
> BTW, this seems to show up slightly more frequently although I've seen
> it a couple of times before without your patch too so it's probably
> unrelated:

Frederic, could you have a look?

> WARNING: CPU: 0 PID: 1244 at arch/x86/kernel/hw_breakpoint.c:121
> arch_install_hw_breakpoint+0x284/0x2f0
> Can't find any breakpoint slot
> CPU: 0 PID: 1244 Comm: trinity-c0 Not tainted 4.7.0+ #73
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/20
> 14
> ffffffff83a1a5a0 ffff880116b6f860 ffffffff81d75571 ffff880116b6f8d8
> 0000000000000000 ffff880116b6f8a8 ffffffff810fd28f ffff880115fb5a00
> ffff880100000079 ffffed0022d6df17 0000000000000004 ffff88010e202a80
> Call Trace:
> [<ffffffff81d75571>] dump_stack+0x65/0x84
> [<ffffffff810fd28f>] __warn+0x17f/0x1a0
> [<ffffffff810fd342>] warn_slowpath_fmt+0x92/0xb0
> [<ffffffff810fd2b0>] ? __warn+0x1a0/0x1a0
> [<ffffffff8135b5ba>] ? perf_event_update_userpage+0x3ca/0x660
> [<ffffffff81064144>] arch_install_hw_breakpoint+0x284/0x2f0
> [<ffffffff81371e44>] hw_breakpoint_add+0xd4/0x100
> [<ffffffff81354d37>] event_sched_in.isra.100+0x3a7/0xa40
> [<ffffffff813554d3>] group_sched_in+0x103/0x3e0
> [<ffffffff81066579>] ? sched_clock+0x9/0x10
> [<ffffffff81355fbd>] ctx_sched_in+0x80d/0x16f0
> [<ffffffff81356f00>] perf_event_sched_in+0x60/0x80
> [<ffffffff81356f80>] ctx_resched+0x60/0xa0
> [<ffffffff81357d67>] __perf_install_in_context+0x247/0x320
> [<ffffffff81357b20>] ? __perf_event_enable+0xb60/0xb60
> [<ffffffff81347fa0>] ? perf_duration_warn+0x40/0x40
> [<ffffffff813480b5>] remote_function+0x115/0x1a0
> [<ffffffff81347fa0>] ? perf_duration_warn+0x40/0x40
> [<ffffffff8125d801>] generic_exec_single+0x191/0x290
> [<ffffffff81347fa0>] ? perf_duration_warn+0x40/0x40
> [<ffffffff8125db2e>] smp_call_function_single+0xde/0x350
> [<ffffffff8125da50>] ? generic_smp_call_function_single_interrupt+0x10/0x10
> [<ffffffff81341f80>] perf_install_in_context+0x200/0x370
> [<ffffffff81341d80>] ? perf_remove_from_context+0xc0/0xc0
> [<ffffffff81357b20>] ? __perf_event_enable+0xb60/0xb60
> [<ffffffff81361482>] SYSC_perf_event_open+0xd62/0x1cf0
> [<ffffffff81360720>] ? perf_event_set_output+0x400/0x400
> [<ffffffff81dd4603>] ? __this_cpu_preempt_check+0x13/0x20
> [<ffffffff81369e80>] ? perf_pmu_unregister+0x470/0x470
> [<ffffffff81369e89>] SyS_perf_event_open+0x9/0x10
> [<ffffffff81005391>] do_syscall_64+0x1a1/0x460
> [<ffffffff813742fa>] ? __context_tracking_enter+0xaa/0x200
> [<ffffffff8389746a>] entry_SYSCALL64_slow_path+0x25/0x25
> ---[ end trace 966c767fd836202d ]---