Am 07.06.2012 23:39, schrieb Martin Pärtel: > On 06/08/2012 12:26 AM, Richard Weinberger wrote: > >> Am 07.06.2012 22:59, schrieb Martin Pärtel: >>> Signal handlers in UML guest processes now get correct siginfo_t fields >>> for SIGTRAP, SIGFPE, SIGILL and SIGBUS. Specifically, si_addr and si_code >>> are now correct where previously they were si_addr = NULL and si_code = 128. >> >> What exactly is broken? >> In my SIGSEGV test case si_addr is not NULL, it contains the correct >> faulting address. >> > > > SIGSEGV is probably fine. At least SIGFPE is not. Test program below. > >>> + >>> + ptrace(PTRACE_GETSIGINFO, pid, 0,&si); >>> + >> >> Doesn't this leak the host siginfo_t into the guest? >> > > > Docs for PTRACE_GETSIGINFO say `si' gets a copy. After that, `si' is not used > for anything other than giving it to the guest. But I really can't say I > understand the surrounding code too well so please review carefully :)
I was not talking about a memory leak. What I meant was a information leak. Using the host siginfo_t a guest process may get it's UID, PID, memory location, etc... on the host side. Anyway, thanks for the test case! This seems to be really broken. I had only a few minutes to look at the issue but I think the correct way to fix is changing arch/um/kernel/trap.c:relay_signal() to use force_sig_info() instead of force_sig(). Create siginfo_t and fill by hand like segv() does. Thanks, //richard
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