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/x86_64/kernel/signal.c | 2 +- arch/x86_64/kernel/traps.c | 6 ++++-- arch/x86_64/mm/fault.c | 15 +++------------ arch/x86_64/mm/init.c | 33 --------------------------------- 4 files changed, 8 insertions(+), 48 deletions(-) (limited to 'arch/x86_64') diff --git a/arch/x86_64/kernel/signal.c b/arch/x86_64/kernel/signal.c index 4886afcd628..739175b01e0 100644 --- a/arch/x86_64/kernel/signal.c +++ b/arch/x86_64/kernel/signal.c @@ -487,7 +487,7 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags) void signal_fault(struct pt_regs *regs, void __user *frame, char *where) { struct task_struct *me = current; - if (exception_trace) + if (show_unhandled_signals && printk_ratelimit()) printk("%s[%d] bad frame in %s frame:%p rip:%lx rsp:%lx orax:%lx\n", me->comm,me->pid,where,frame,regs->rip,regs->rsp,regs->orig_rax); diff --git a/arch/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c index 8713ad4a4db..03888420775 100644 --- a/arch/x86_64/kernel/traps.c +++ b/arch/x86_64/kernel/traps.c @@ -584,7 +584,8 @@ static void __kprobes do_trap(int trapnr, int signr, char *str, tsk->thread.error_code = error_code; tsk->thread.trap_no = trapnr; - if (exception_trace && unhandled_signal(tsk, signr)) + if (show_unhandled_signals && unhandled_signal(tsk, signr) && + printk_ratelimit()) printk(KERN_INFO "%s[%d] trap %s rip:%lx rsp:%lx error:%lx\n", tsk->comm, tsk->pid, str, @@ -688,7 +689,8 @@ asmlinkage void __kprobes do_general_protection(struct pt_regs * regs, tsk->thread.error_code = error_code; tsk->thread.trap_no = 13; - if (exception_trace && unhandled_signal(tsk, SIGSEGV)) + if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) && + printk_ratelimit()) printk(KERN_INFO "%s[%d] general protection rip:%lx rsp:%lx error:%lx\n", tsk->comm, tsk->pid, diff --git a/arch/x86_64/mm/fault.c b/arch/x86_64/mm/fault.c index 2074bddd4f0..5e9ac70c135 100644 --- a/arch/x86_64/mm/fault.c +++ b/arch/x86_64/mm/fault.c @@ -221,16 +221,6 @@ static int is_errata93(struct pt_regs *regs, unsigned long address) return 0; } -int unhandled_signal(struct task_struct *tsk, int sig) -{ - if (is_init(tsk)) - return 1; - if (tsk->ptrace & PT_PTRACED) - return 0; - return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) || - (tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL); -} - static noinline void pgtable_bad(unsigned long address, struct pt_regs *regs, unsigned long error_code) { @@ -302,7 +292,7 @@ static int vmalloc_fault(unsigned long address) } static int page_fault_trace; -int exception_trace = 1; +int show_unhandled_signals = 1; /* * This routine handles page faults. It determines the address, @@ -494,7 +484,8 @@ bad_area_nosemaphore: (address >> 32)) return; - if (exception_trace && unhandled_signal(tsk, SIGSEGV)) { + if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) && + printk_ratelimit()) { printk( "%s%s[%d]: segfault at %016lx rip %016lx rsp %016lx error %lx\n", tsk->pid > 1 ? KERN_INFO : KERN_EMERG, diff --git a/arch/x86_64/mm/init.c b/arch/x86_64/mm/init.c index 381c2ecd407..88678e82e23 100644 --- a/arch/x86_64/mm/init.c +++ b/arch/x86_64/mm/init.c @@ -697,39 +697,6 @@ int kern_addr_valid(unsigned long addr) return pfn_valid(pte_pfn(*pte)); } -#ifdef CONFIG_SYSCTL -#include - -static ctl_table debug_table2[] = { - { - .ctl_name = 99, - .procname = "exception-trace", - .data = &exception_trace, - .maxlen = sizeof(int), - .mode = 0644, - .proc_handler = proc_dointvec - }, - {} -}; - -static ctl_table debug_root_table2[] = { - { - .ctl_name = CTL_DEBUG, - .procname = "debug", - .mode = 0555, - .child = debug_table2 - }, - {} -}; - -static __init int x8664_sysctl_init(void) -{ - register_sysctl_table(debug_root_table2); - return 0; -} -__initcall(x8664_sysctl_init); -#endif - /* A pseudo VMA to allow ptrace access for the vsyscall page. This only covers the 64bit vsyscall page now. 32bit has a real VMA now and does not need special handling anymore. */ -- cgit v1.2.3-18-g5258