Messages in this thread | | | Date | Sat, 9 Aug 2014 20:18:19 -0700 | Subject | Re: Runtime trouble with commit dbd952127d (seccomp: introduce writer locking) | From | Kees Cook <> |
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On Sat, Aug 9, 2014 at 6:47 PM, Guenter Roeck <private@roeck-us.net> wrote: > Hi folks, > > I am having some trouble with commit dbd952127d (seccomp: introduce > writer locking) when running my qemu tests on the upstream kernel.
Eek, sorry this is causing you trouble!
> With powerpc, I get the following crash. > > ftrace: allocating 20093 entries in 59 pages > ------------[ cut here ]------------ > kernel BUG at kernel/fork.c:1108!
For your tree, does this resolve to copy_seccomp()'s
BUG_ON(!spin_is_locked(¤t->sighand->siglock));
line?
> Oops: Exception in kernel mode, sig: 5 [#1] > PREEMPT PowerMac > Modules linked in: > CPU: 0 PID: 0 Comm: swapper Not tainted 3.16.0-yocto-standard+ #1 > task: c08a03d0 ti: c08e4000 task.ti: c08e4000 > NIP: c002b98c LR: c002b988 CTR: c03837ec > REGS: c08e5e30 TRAP: 0700 Not tainted (3.16.0-yocto-standard+) > MSR: 00021032 <ME,IR,DR,RI> CR: 22282048 XER: 20000000 > > GPR00: c002b988 c08e5ee0 c08a03d0 00000001 c0a9b878 00000800 c783603c > 00000020 > GPR08: c783603c 00000003 00000001 c08f61fc 22222044 00000000 07c5ac10 > 00800300 > GPR16: c7870000 00000010 00000000 07de7fa4 00000000 c08f594c c08f0000 > c78702d0 > GPR24: 00000000 c08f0000 c08f5940 c000422c c08a8ea0 c7870310 00000000 > c7808400 > NIP [c002b98c] copy_process.part.52+0x794/0x13e4 > LR [c002b988] copy_process.part.52+0x790/0x13e4 > Call Trace: > [c08e5ee0] [c002b988] copy_process.part.52+0x790/0x13e4 (unreliable) > [c08e5f60] [c002c768] do_fork+0xb8/0x3bc > [c08e5fa0] [c00041c8] rest_init+0x30/0x94 > [c08e5fb0] [c083cf98] start_kernel+0x368/0x37c > [c08e5ff0] [00003438] 0x3438 > Instruction dump: > 7d400124 38600001 48027e95 55e903e1 41820b84 80e202c0 90f002c0 81420570 > 91500570 38600001 48027e75 39400001 <0f0a0000> 81420568 8162056c 91500568 > ---[ end trace dc8fa200cb88537f ]--- > > With mips (both 32 bit and 64 bit), I get > > NR_IRQS:256 > CPU frequency 200.00 MHz > Console: colour dummy device 80x25 > console [tty0] enabled > bootconsole [uart0] disabled > > [ and then there is silence ] > > In all cases I bisected the problem to the above mentioned commit. > > Failures are seen in both linux-next and the tip of Linus' tree. > Test results are on http://server.roeck-us.net:8010/builders > (look for qwmu results). Build and test scripts are in the mips, > mips64, and powerpc subdirectories of > https://github.com/groeck/linux-build-test/tree/master/rootfs. > > Any idea, anyone, what might be going on, or how I could do to > help tracking this down ?
Can you send me your .config for the powerpc case? There must be something going on here with the spinlock, but I don't see how, since the lines immediately before the copy_seccomp call take the lock...
Is there something special going on here for the "pid 0" case?
-Kees
-- Kees Cook Chrome OS Security
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