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From: "simon.marchi at ericsson dot com" <sourceware-bugzilla@sourceware.org> To: gdb-prs@sourceware.org Subject: [Bug server/17302] gdbserver function call + detach crashes inferior process Date: Wed, 03 Sep 2014 15:51:00 -0000 [thread overview] Message-ID: <bug-17302-4717-FN99mH6dC8@http.sourceware.org/bugzilla/> (raw) In-Reply-To: <bug-17302-4717@http.sourceware.org/bugzilla/> https://sourceware.org/bugzilla/show_bug.cgi?id=17302 --- Comment #2 from Simon Marchi <simon.marchi at ericsson dot com> --- I found that during the manual call to a function by gdbserver, a segmentation fault/SIGSEGV is generated. When detaching, gdbserver delivers the pending SIGSEGV, causing the crash of the detached process. When preparing the inferior call, gdb starts by expanding a stack a bit. It then places a breakpoint instruction (0xCC) somewhere in that area. It then prepares the dummy frame, including writing the return address, which is the address where the 0xCC is. So when the function ends, execution should go where the breakpoint and it should stop. However, since stack is generally not executable, when the processor tries to "execute" the breakpoint instruction, a segmentation fault/SIGSEGV is generated instead of the normal SIGTRAP. When making the stack executable, the problem disappears, so I am quite confident that this is the reason. In order to make the stack executable, I use execstack (it modifies a flag in the binary): $ execstack -s binary I have no idea why this only happens in gdbserver, and not in gdb. -- You are receiving this mail because: You are on the CC list for the bug.
next prev parent reply other threads:[~2014-09-03 15:51 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-08-22 13:26 [Bug server/17302] New: " simon.marchi at ericsson dot com 2014-08-22 13:28 ` [Bug server/17302] " simon.marchi at ericsson dot com 2014-09-03 15:51 ` simon.marchi at ericsson dot com [this message] 2014-09-03 15:51 ` simon.marchi at ericsson dot com 2014-09-03 18:25 ` simon.marchi at ericsson dot com 2014-12-10 21:14 ` cvs-commit at gcc dot gnu.org
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