Messages in this thread | | | From | David Howells <> | Subject | Re: keys: GPF in request_key | Date | Wed, 01 Feb 2017 13:11:32 +0000 |
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Dmitry Vyukov <dvyukov@google.com> wrote:
> Code: 41 54 49 89 f4 53 49 89 d7 48 89 fb 48 83 ec 08 e8 d1 50 67 ff > 49 8d 7c 24 10 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> > 3c 02 00 0f 85 35 02 00 00 49 83 7c 24 10 00 0f 84 bb 01 00
This disassembles to:
0: 41 54 push %r12 2: 49 89 f4 mov %rsi,%r12 5: 53 push %rbx 6: 49 89 d7 mov %rdx,%r15 9: 48 89 fb mov %rdi,%rbx c: 48 83 ec 08 sub $0x8,%rsp 10: e8 d1 50 67 ff callq 0xffffffffff6750e6 15: 49 8d 7c 24 10 lea 0x10(%r12),%rdi 1a: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 21: fc ff df 24: 48 89 fa mov %rdi,%rdx 27: 48 c1 ea 03 shr $0x3,%rdx 2b:* 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction 2f: 0f 85 35 02 00 00 jne 0x26a 35: 49 83 7c 24 10 00 cmpq $0x0,0x10(%r12) 3b: 0f .byte 0xf 3c: 84 .byte 0x84 3d: bb .byte 0xbb 3e: 01 00 add %eax,(%rax)
I can see that RAX got loaded from the instruction at 0x1a, but the code doesn't look very much like what I get out of the compiler (your compiled function is also at least double the size of what I get, presumably due to kasan?).
Can you disassemble __key_link_begin() for me and send me your config?
In particular, 0xdffffc0000000000 looks very weird. Is this code validating the pointer in R12?
David
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