Messages in this thread | | | Date | Mon, 14 Sep 2020 11:49:27 -0500 | From | Josh Poimboeuf <> | Subject | Re: WARNING: can't access registers at asm_sysvec_call_function_single |
| |
On Sun, Sep 13, 2020 at 11:05:21PM +0200, Thomas Gleixner wrote: > On Tue, Sep 08 2020 at 13:16, syzbot wrote: > > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: f4d51dff Linux 5.9-rc4 > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=1455d4f9900000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=a9075b36a6ae26c9 > > dashboard link: https://syzkaller.appspot.com/bug?extid=bc9dbf05dcc151e9b972 > > compiler: gcc (GCC) 10.1.0-syz 20200507 > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+bc9dbf05dcc151e9b972@syzkaller.appspotmail.com > > > > WARNING: can't access registers at asm_sysvec_call_function_single+0x12/0x20 arch/x86/include/asm/idtentry.h:589 > > That's the ORC unwinder complaining, but I have no idea why...
0000000000000cd0 <asm_sysvec_call_function_single>: cd0: 90 nop cd1: 90 nop cd2: 90 nop cd3: 6a ff pushq $0xffffffffffffffff cd5: e8 b6 03 00 00 callq 1090 <error_entry> cda: 48 89 e7 mov %rsp,%rdi cdd: e8 00 00 00 00 callq ce2 <asm_sysvec_call_function_single+0x12> cde: R_X86_64_PLT32 sysvec_call_function_single-0x4 ce2: e9 69 04 00 00 jmpq 1150 <error_return> ce7: 66 0f 1f 84 00 00 00 nopw 0x0(%rax,%rax,1) cee: 00 00
This is a head scratcher. The ORC data looks ok, at least when I build it on my system. It's expecting to find pt_regs at the top of the stack after returning from sysvec_call_function_single(). But it can't dereference the regs for some reason.
So either it's a bug in ORC data or unwinder (not likely) or the stack pointer got corrupted somehow (also seems unlikely)...
-- Josh
| |