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From: "jreiser at bitwagon dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libgcc/66874] New: RFE: x86_64_fallback_frame_state more robust
Date: Tue, 14 Jul 2015 23:58:00 -0000 [thread overview]
Message-ID: <bug-66874-4@http.gcc.gnu.org/bugzilla/> (raw)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66874
Bug ID: 66874
Summary: RFE: x86_64_fallback_frame_state more robust
Product: gcc
Version: 5.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libgcc
Assignee: unassigned at gcc dot gnu.org
Reporter: jreiser at bitwagon dot com
Target Milestone: ---
In libgcc/config/i386/linux-unwind.h function x86_64_fallback_frame_state()
please check the value of pc before accessing memory in the statement:
-----
unsigned char *pc = context->ra;
// snip
if (*(unsigned char *)(pc+0) == 0x48
&& *(unsigned long long *)(pc+1) == RT_SIGRETURN_SYSCALL)
-----
I have seen pc values of 0, 2, 0xffffffff, etc due to missing or incorrect
debug info, particularly when the code that is being unwound was compiled with
no frame pointer, or was compiled by other compilers. The result is SIGSEGV,
which is a major disappointment.
I suggest a check in the spirit of:
if ((unsigned long)pc < 4096)
return _URC_END_OF_STACK;
or similar. Obviously this is heuristic, but it is much better than SIGSEGV.
next reply other threads:[~2015-07-14 23:58 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-14 23:58 jreiser at bitwagon dot com [this message]
2015-07-15 3:04 ` [Bug libgcc/66874] " hjl.tools at gmail dot com
2024-02-23 17:19 ` [Bug target/66874] " sjames at gcc dot gnu.org
2024-02-23 17:24 ` jakub at gcc dot gnu.org
2024-02-23 17:25 ` sjames at gcc dot gnu.org
2024-02-23 19:39 ` schwab@linux-m68k.org
2024-02-26 15:08 ` sjames at gcc dot gnu.org
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