Re: ktrace -p nonexistent process causes a panic

[matthew sporleder <msporleder%gmail.com@localhost>]

On Thu, Dec 29, 2011 at 8:26 AM, matthew sporleder 
<msporleder%gmail.com@localhost> wrote:
> On Thu, Dec 29, 2011 at 12:20 AM, Emmanuel Dreyfus 
> <manu%netbsd.org@localhost> wrote:
>> Hello
>>
>> I can reliabily crash latest netbsd-5 kernel with an unprivilegied
>> ktrace -p on an unexisting process:
>>
>> $ ktrace -p 666
>> panic: kernel diagnostic assertion "fp->f_count == 0" failed: file
>> "/usr/src-5/sys/kern/kern_descrip.c", line 1115
>> fatal breakpoint trap in supervisor mode
>> trap type 1 code 0 eip c03a821c cs 9 eflags 246 cr2 bbb52b80 ilevel 0
>> Stopped in pid 547.1 (ktrace) at        netbsd:breakpoint+0x4:  popl
>> %ebp
>> db> bt
>> breakpoint(c045b6cb,cb802c28,c0470cc0,c02d07f2,cb7a0460,cb465ecc,cb802c0
>> c,c02da20f,cb465f38,3) at netbsd:breakpoint+0x4
>> panic(c0465598,c0429e91,c0449ee2,c044a0f4,45b,3,cb802c5c,c02d00df,c0429e
>> 91,c044a0f4) at netbsd:panic+0x1a6
>> __kernassert(c0429e91,c044a0f4,45b,c0449ee2,cb7b3500,3,cb802cdc,c02dbfdb
>> ,cb553184,cb553184) at netbsd:__kernassert+0x39
>> ffree(cb553184,cb553184,3,cb7a0460,cb7a0460,cb7a03a0,cb7e7c40,80495a2,0,
>> 0) at netbsd:ffree+0x6f
>> sys_ktrace(cb7b3500,cb802d00,cb802d28,bbb52b80,bbb52000,cb7b5d44,1,80495
>> a2,1000000,13be) at netbsd:sys_ktrace+0x12b
>> syscall(cb802d48,1f,1f,1f,1f,8049564,80495a3,bfbfec18,1000000,1) at
>> netbsd:syscall+0xc7
>>
>> This is annoying since it can be very easily tirggered by mistake: an
>> unrpivilegied user doing a typo can bring down the system.
>>
>> Known problem? PR already filled? If not, is it reproductible on other
>> systems than mine?
>>
>
>
> I just rebooted my system with it:
>
> NetBSD 5.1 (PANIX-VC) #2: Mon Aug  8 22:10:38 EDT 2011
>       
>  root%juggler.panix.com@localhost:/misc/obj/misc/devel/netbsd/5.1/src/sys/arch/amd64/compile/PANIX-VC

tmp $ ktrace -p 23545
panic: kernel diagnostic assertion "fp->f_count == 0" failed: file
"/misc/devel/netbsd/5.1/src/sys/kern/kern_descrip.c", line 1115
Begin traceback...
copyright() at netbsd:__kernassert+0x30e55
pool_cache_get_paddr() at netbsd:pool_cache_get_paddr+0xbd
fd_unused() at netbsd:fd_unused+0x16a
__kernassert() at netbsd:__kernassert+0x2d
ffree() at netbsd:ffree+0x63
sys_ktrace() at netbsd:sys_ktrace+0x13b
syscall() at netbsd:syscall+0xb4
End traceback...

dump to dev 142,1 not possible
rebooting...