Mail Archives: cygwin/2009/07/22/18:28:07
On Wed, Jul 22, 2009 at 09:18:57PM +0000, Eric Blake wrote:
>POSIX requires that for SIGSEGV and SIGBUS, the si_addr member of siginfo_t be
>set to the memory address where access failed, and not the address of the
>instruction attempting to access that address (for SIGILL and SIGFPE, the
>si_addr field is correct, and for all other signals, the si_addr is unspecified
>by POSIX so it might as well be the faulting instruction).
>
>Fixing si_addr to contain the correct information will make it possible to
>patch libsigsegv to avoid installing an SEH handler for all but stack
>overflow. (Without this patch, I think I can still patch libsigsegv to honor
>SIGSEGV, but it will be a much bigger hack of still installing a libsigsegv SEH
>handler that sniffs the faulting address, then in the SIGSEGV handler refers to
>the address that was sniffed).
>
>2009-07-22 Eric Blake <ebb9 AT byu DOT net>
>
> * exceptions.cc (handle_exceptions): Set si_addr according to
> POSIX for SIGSEGV.
>
>diff --git a/winsup/cygwin/exceptions.cc b/winsup/cygwin/exceptions.cc
>index 7663285..df02489 100644
>--- a/winsup/cygwin/exceptions.cc
>+++ b/winsup/cygwin/exceptions.cc
>@@ -686,7 +686,8 @@ _cygtls::handle_exceptions (EXCEPTION_RECORD *e,
>exception_list *frame, CONTEXT
> me.signal_exit (0x80 | si.si_signo); // Flag signal + core dump
> }
>
>- si.si_addr = (void *) in->Eip;
>+ si.si_addr = (si.si_signo == SIGSEGV || si.si_signo == SIGBUS
>+ ? (void *) e->ExceptionInformation[1] : (void *) in->Eip);
> si.si_errno = si.si_pid = si.si_uid = 0;
> me.incyg++;
> sig_send (NULL, si, &me); // Signal myself
Looks ok. Please check in.
Thanks for the patch.
cgf
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