linux-kernel - Re: [PATCH v2] rcu: Avoid stack overflow due to __rcu_irq_enter_check

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <b868ccf3-3ae2-d6cb-4e1c-e2536f1e959e@huawei.com>
Date:   Tue, 10 Jan 2023 08:55:07 +0800
From:   Zheng Yejian <zhengyejian1@...wei.com>
To:     <paulmck@...nel.org>
CC:     <frederic@...nel.org>, <jiangshanlai@...il.com>,
        <joel@...lfernandes.org>, <josh@...htriplett.org>,
        <linux-kernel@...r.kernel.org>, <mathieu.desnoyers@...icios.com>,
        <mhiramat@...nel.org>, <peterz@...radead.org>,
        <quic_neeraju@...cinc.com>, <rcu@...r.kernel.org>,
        <rostedt@...dmis.org>
Subject: Re: [PATCH v2] rcu: Avoid stack overflow due to
 __rcu_irq_enter_check_tick() being kprobe-ed

On 2023/1/10 04:04, Paul E. McKenney wrote:
> On Fri, Jan 06, 2023 at 03:09:34PM +0800, Zheng Yejian wrote:
>> Register kprobe on __rcu_irq_enter_check_tick() can cause kernel stack
>> overflow [1]. This issue can be reproduced by enabling CONFIG_NO_HZ_FULL
>> and boot kernel with argument "nohz_full=" then execute like:
>>    # cd /sys/kernel/tracing/
>>    # echo 'p:mp1 __rcu_irq_enter_check_tick' >> kprobe_events
>>    # echo 1 > events/kprobes/enable
>>
>> It seems __rcu_irq_enter_check_tick() should not be kprobe-ed, so add
>> it into kprobe blacklist with NOKPROBE_SYMBOL(). This may have less impact
>> than tagging as 'noinstr' which was discussed but not concluded in
>> Link: https://lore.kernel.org/all/20221119040049.795065-1-zhengyejian1@huawei.com/
> 
> Queued for testing and further review, thank you!
> 
> Could you please check the wordsmithed version below?

It looks much better, thank you!

--
Best regards,
Zheng Yejian

> 
> 							Thanx, Paul
> 
> ------------------------------------------------------------------------
> 
> commit 5ceaf736da841c4bdb03049c7d6e0c0c41253161
> Author: Zheng Yejian <zhengyejian1@...wei.com>
> Date:   Fri Jan 6 15:09:34 2023 +0800
> 
>      rcu: Avoid stack overflow due to __rcu_irq_enter_check_tick() being kprobe-ed
>      
>      Registering a kprobe on __rcu_irq_enter_check_tick() can cause kernel
>      stack overflow as shown below. This issue can be reproduced by enabling
>      CONFIG_NO_HZ_FULL and booting the kernel with argument "nohz_full=",
>      and then giving the following commands at the shell prompt:
>      
>        # cd /sys/kernel/tracing/
>        # echo 'p:mp1 __rcu_irq_enter_check_tick' >> kprobe_events
>        # echo 1 > events/kprobes/enable
>      
>      This commit therefore adds __rcu_irq_enter_check_tick() to the kprobes
>      blacklist using NOKPROBE_SYMBOL().
>      
>      Insufficient stack space to handle exception!
>      ESR: 0x00000000f2000004 -- BRK (AArch64)
>      FAR: 0x0000ffffccf3e510
>      Task stack:     [0xffff80000ad30000..0xffff80000ad38000]
>      IRQ stack:      [0xffff800008050000..0xffff800008058000]
>      Overflow stack: [0xffff089c36f9f310..0xffff089c36fa0310]
>      CPU: 5 PID: 190 Comm: bash Not tainted 6.2.0-rc2-00320-g1f5abbd77e2c #19
>      Hardware name: linux,dummy-virt (DT)
>      pstate: 400003c5 (nZcv DAIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>      pc : __rcu_irq_enter_check_tick+0x0/0x1b8
>      lr : ct_nmi_enter+0x11c/0x138
>      sp : ffff80000ad30080
>      x29: ffff80000ad30080 x28: ffff089c82e20000 x27: 0000000000000000
>      x26: 0000000000000000 x25: ffff089c02a8d100 x24: 0000000000000000
>      x23: 00000000400003c5 x22: 0000ffffccf3e510 x21: ffff089c36fae148
>      x20: ffff80000ad30120 x19: ffffa8da8fcce148 x18: 0000000000000000
>      x17: 0000000000000000 x16: 0000000000000000 x15: ffffa8da8e44ea6c
>      x14: ffffa8da8e44e968 x13: ffffa8da8e03136c x12: 1fffe113804d6809
>      x11: ffff6113804d6809 x10: 0000000000000a60 x9 : dfff800000000000
>      x8 : ffff089c026b404f x7 : 00009eec7fb297f7 x6 : 0000000000000001
>      x5 : ffff80000ad30120 x4 : dfff800000000000 x3 : ffffa8da8e3016f4
>      x2 : 0000000000000003 x1 : 0000000000000000 x0 : 0000000000000000
>      Kernel panic - not syncing: kernel stack overflow
>      CPU: 5 PID: 190 Comm: bash Not tainted 6.2.0-rc2-00320-g1f5abbd77e2c #19
>      Hardware name: linux,dummy-virt (DT)
>      Call trace:
>       dump_backtrace+0xf8/0x108
>       show_stack+0x20/0x30
>       dump_stack_lvl+0x68/0x84
>       dump_stack+0x1c/0x38
>       panic+0x214/0x404
>       add_taint+0x0/0xf8
>       panic_bad_stack+0x144/0x160
>       handle_bad_stack+0x38/0x58
>       __bad_stack+0x78/0x7c
>       __rcu_irq_enter_check_tick+0x0/0x1b8
>       arm64_enter_el1_dbg.isra.0+0x14/0x20
>       el1_dbg+0x2c/0x90
>       el1h_64_sync_handler+0xcc/0xe8
>       el1h_64_sync+0x64/0x68
>       __rcu_irq_enter_check_tick+0x0/0x1b8
>       arm64_enter_el1_dbg.isra.0+0x14/0x20
>       el1_dbg+0x2c/0x90
>       el1h_64_sync_handler+0xcc/0xe8
>       el1h_64_sync+0x64/0x68
>       __rcu_irq_enter_check_tick+0x0/0x1b8
>       arm64_enter_el1_dbg.isra.0+0x14/0x20
>       el1_dbg+0x2c/0x90
>       el1h_64_sync_handler+0xcc/0xe8
>       el1h_64_sync+0x64/0x68
>       __rcu_irq_enter_check_tick+0x0/0x1b8
>       [...]
>       el1_dbg+0x2c/0x90
>       el1h_64_sync_handler+0xcc/0xe8
>       el1h_64_sync+0x64/0x68
>       __rcu_irq_enter_check_tick+0x0/0x1b8
>       arm64_enter_el1_dbg.isra.0+0x14/0x20
>       el1_dbg+0x2c/0x90
>       el1h_64_sync_handler+0xcc/0xe8
>       el1h_64_sync+0x64/0x68
>       __rcu_irq_enter_check_tick+0x0/0x1b8
>       arm64_enter_el1_dbg.isra.0+0x14/0x20
>       el1_dbg+0x2c/0x90
>       el1h_64_sync_handler+0xcc/0xe8
>       el1h_64_sync+0x64/0x68
>       __rcu_irq_enter_check_tick+0x0/0x1b8
>       el1_interrupt+0x28/0x60
>       el1h_64_irq_handler+0x18/0x28
>       el1h_64_irq+0x64/0x68
>       __ftrace_set_clr_event_nolock+0x98/0x198
>       __ftrace_set_clr_event+0x58/0x80
>       system_enable_write+0x144/0x178
>       vfs_write+0x174/0x738
>       ksys_write+0xd0/0x188
>       __arm64_sys_write+0x4c/0x60
>       invoke_syscall+0x64/0x180
>       el0_svc_common.constprop.0+0x84/0x160
>       do_el0_svc+0x48/0xe8
>       el0_svc+0x34/0xd0
>       el0t_64_sync_handler+0xb8/0xc0
>       el0t_64_sync+0x190/0x194
>      SMP: stopping secondary CPUs
>      Kernel Offset: 0x28da86000000 from 0xffff800008000000
>      PHYS_OFFSET: 0xfffff76600000000
>      CPU features: 0x00000,01a00100,0000421b
>      Memory Limit: none
>      
>      Link: https://lore.kernel.org/all/20221119040049.795065-1-zhengyejian1@huawei.com/
>      Fixes: aaf2bc50df1f ("rcu: Abstract out rcu_irq_enter_check_tick() from rcu_nmi_enter()")
>      Signed-off-by: Zheng Yejian <zhengyejian1@...wei.com>
>      Cc: stable@...r.kernel.org
>      Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
> 
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index a6181b76fd5ab..63545d79da51c 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -640,6 +640,7 @@ void __rcu_irq_enter_check_tick(void)
>   	}
>   	raw_spin_unlock_rcu_node(rdp->mynode);
>   }
> +NOKPROBE_SYMBOL(__rcu_irq_enter_check_tick);
>   #endif /* CONFIG_NO_HZ_FULL */
>   
>   /*