From abd4f7505bafdd6c5319fe3cb5caf9af6104e17a Mon Sep 17 00:00:00 2001 From: Masoud Asgharifard Sharbiani Date: Sun, 22 Jul 2007 11:12:28 +0200 Subject: x86: i386-show-unhandled-signals-v3 This patch makes the i386 behave the same way that x86_64 does when a segfault happens. A line gets printed to the kernel log so that tools that need to check for failures can behave more uniformly between debug.show_unhandled_signals sysctl variable to 0 (or by doing echo 0 > /proc/sys/debug/exception-trace) Also, all of the lines being printed are now using printk_ratelimit() to deny the ability of DoS from a local user with a program like the following: main() { while (1) if (!fork()) *(int *)0 = 0; } This new revision also includes the fix that Andrew did which got rid of new sysctl that was added to the system in earlier versions of this. Also, 'show-unhandled-signals' sysctl has been renamed back to the old 'exception-trace' to avoid breakage of people's scripts. AK: Enabling by default for i386 will be likely controversal, but let's see what happens AK: Really folks, before complaining just fix your segfaults AK: I bet this will find a lot of silent issues Signed-off-by: Masoud Sharbiani Signed-off-by: Andi Kleen [ Personally, I've found the complaints useful on x86-64, so I'm all for this. That said, I wonder if we could do it more prettily.. -Linus ] Signed-off-by: Linus Torvalds --- arch/i386/kernel/signal.c | 7 +++++++ arch/i386/kernel/traps.c | 7 +++++++ 2 files changed, 14 insertions(+) (limited to 'arch/i386/kernel') diff --git a/arch/i386/kernel/signal.c b/arch/i386/kernel/signal.c index d574e38f0f77..f5dd85656c18 100644 --- a/arch/i386/kernel/signal.c +++ b/arch/i386/kernel/signal.c @@ -199,6 +199,13 @@ asmlinkage int sys_sigreturn(unsigned long __unused) return eax; badframe: + if (show_unhandled_signals && printk_ratelimit()) + printk("%s%s[%d] bad frame in sigreturn frame:%p eip:%lx" + " esp:%lx oeax:%lx\n", + current->pid > 1 ? KERN_INFO : KERN_EMERG, + current->comm, current->pid, frame, regs->eip, + regs->esp, regs->orig_eax); + force_sig(SIGSEGV, current); return 0; } diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c index 57772a18c394..438949da3b63 100644 --- a/arch/i386/kernel/traps.c +++ b/arch/i386/kernel/traps.c @@ -618,6 +618,13 @@ fastcall void __kprobes do_general_protection(struct pt_regs * regs, current->thread.error_code = error_code; current->thread.trap_no = 13; + if (show_unhandled_signals && unhandled_signal(current, SIGSEGV) && + printk_ratelimit()) + printk(KERN_INFO + "%s[%d] general protection eip:%lx esp:%lx error:%lx\n", + current->comm, current->pid, + regs->eip, regs->esp, error_code); + force_sig(SIGSEGV, current); return; -- cgit v1.2.3