Messages in this thread | | | From | "Petr Vandrovec Ing. VTEI" <> | Date | Mon, 6 Sep 1999 21:16:48 MET-1 | Subject | debug registers in 2.3.x |
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Hi, I was looking into usage of ia32 debug registers in 2.3.16 kernel and I found that anybody with ptrace rights to any process can confuse vm86 applications, if I did not miss something, because of we are setting DR7 lazy, but we do not check thread.debugreg[7] in do_debug() if exception came from VM86 mode (doing handle_vm86_trap() doing in turn do_int() or send_sig(SIGTRAP)). We check this if exception came from 32-bit code and I think that we should do this check in all cases, not only for 32bit code. Is it intentional (I do not think...) or did I miss DR7 clear/load somewhere else? Or is VMM using vm86() syscall responsible for handling this spurious traps? Thanks, Petr Vandrovec vandrove@vc.cvut.cz
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