From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932365AbXGYOuz (ORCPT ); Wed, 25 Jul 2007 10:50:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757014AbXGYOus (ORCPT ); Wed, 25 Jul 2007 10:50:48 -0400 Received: from smtp-out.google.com ([216.239.33.17]:26318 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754712AbXGYOur (ORCPT ); Wed, 25 Jul 2007 10:50:47 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=received:message-id:date:from:to:subject:cc:in-reply-to: mime-version:content-type:content-transfer-encoding: content-disposition:references; b=Nk6ws/stueh9R293roqvD7QlNSFY/6sFSZ4md9DOkCnZIpAYwNMasr13y2FV1n9cs dytbLHHn1NGDSZvv0R4Dg== Message-ID: <4517d1380707250750y3f2808der7ded770702cc6681@mail.gmail.com> Date: Wed, 25 Jul 2007 07:50:28 -0700 From: "Masoud Sharbiani" To: "Kirill Korotaev" Subject: Re: i386-show-unhandled-signals-v3 Cc: akpm@linux-foundation.org, ak@suse.de, linux-kernel@vger.kernel.org In-Reply-To: <46A76210.5020903@openvz.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20070718154759.GA26425@google.com> <46A76210.5020903@openvz.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 7/25/07, Kirill Korotaev wrote: > plz don't enable it by default... :/ > any user can spam syslog with these messages and if syslog is run as root > can take the whole diskspace... Yeah, but: 1) Right now (without this patch), it is enabled by default with _no_ rate control in _all_ kernels; I ran the tiny program that is here, and it wasn't fun to watch. 2) With this patch it will be rate controlled using printk_ratelimit(), thus reducing the amount of spam immensely. Of course, we can disable both of them, is this what you (and everybody else) want? Masoud > Thanks, > Kirill > > Masoud Asgharifard Sharbiani wrote: > > Hello, > > 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. > > > > cheers, > > Masoud Sharbiani > > > > Signed-off-by: Masoud Sharbiani > > Cc: Andi Kleen > > > > --- > > arch/i386/kernel/signal.c | 7 +++++++ > > arch/i386/kernel/traps.c | 7 +++++++ > > arch/i386/mm/fault.c | 10 ++++++++++ > > 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 | 35 ----------------------------------- > > include/asm-x86_64/proto.h | 2 -- > > include/linux/signal.h | 3 +++ > > kernel/signal.c | 10 ++++++++++ > > kernel/sysctl.c | 10 ++++++++++ > > 11 files changed, 55 insertions(+), 52 deletions(-) > > > > diff --git a/arch/i386/kernel/signal.c b/arch/i386/kernel/signal.c > > index d574e38..f5dd856 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 18c1c28..c20283c 100644 > > --- a/arch/i386/kernel/traps.c > > +++ b/arch/i386/kernel/traps.c > > @@ -611,6 +611,13 @@ 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; > > > > diff --git a/arch/i386/mm/fault.c b/arch/i386/mm/fault.c > > index 1ecb3e4..52c940b 100644 > > --- a/arch/i386/mm/fault.c > > +++ b/arch/i386/mm/fault.c > > @@ -283,6 +283,8 @@ static inline int vmalloc_fault(unsigned long address) > > return 0; > > } > > > > +int show_unhandled_signals = 1; > > + > > /* > > * This routine handles page faults. It determines the address, > > * and the problem, and then passes it off to one of the appropriate > > @@ -470,6 +472,14 @@ bad_area_nosemaphore: > > if (is_prefetch(regs, address, error_code)) > > return; > > > > + if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) && > > + printk_ratelimit()) { > > + printk("%s%s[%d]: segfault at %08lx eip %08lx " > > + "esp %08lx error %lx\n", > > + tsk->pid > 1 ? KERN_INFO : KERN_EMERG, > > + tsk->comm, tsk->pid, address, regs->eip, > > + regs->esp, error_code); > > + } > > tsk->thread.cr2 = address; > > /* Kernel addresses are always protection faults */ > > tsk->thread.error_code = error_code | (address >= TASK_SIZE); > > diff --git a/arch/x86_64/kernel/signal.c b/arch/x86_64/kernel/signal.c > > index 290f5d8..f9506f6 100644 > > --- a/arch/x86_64/kernel/signal.c > > +++ b/arch/x86_64/kernel/signal.c > > @@ -480,7 +480,7 @@ 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 74cbeb2..b9660c4 100644 > > --- a/arch/x86_64/kernel/traps.c > > +++ b/arch/x86_64/kernel/traps.c > > @@ -580,7 +580,8 @@ 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, > > @@ -684,7 +685,8 @@ 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 635e58d..0412824 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) > > } > > > > int page_fault_trace = 0; > > -int exception_trace = 1; > > +int show_unhandled_signals = 1; > > > > /* > > * This routine handles page faults. It determines the address, > > @@ -495,7 +485,8 @@ 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 9a0e98a..5096168 100644 > > --- a/arch/x86_64/mm/init.c > > +++ b/arch/x86_64/mm/init.c > > @@ -697,41 +697,6 @@ int kern_addr_valid(unsigned long addr) > > return pfn_valid(pte_pfn(*pte)); > > } > > > > -#ifdef CONFIG_SYSCTL > > -#include > > - > > -extern int exception_trace, page_fault_trace; > > - > > -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. */ > > diff --git a/include/asm-x86_64/proto.h b/include/asm-x86_64/proto.h > > index 85255db..4fad501 100644 > > --- a/include/asm-x86_64/proto.h > > +++ b/include/asm-x86_64/proto.h > > @@ -75,8 +75,6 @@ extern void setup_node_bootmem(int nodeid, unsigned long start, unsigned long en > > extern void early_quirks(void); > > extern void check_efer(void); > > > > -extern int unhandled_signal(struct task_struct *tsk, int sig); > > - > > extern void select_idle_routine(const struct cpuinfo_x86 *c); > > > > extern unsigned long table_start, table_end; > > diff --git a/include/linux/signal.h b/include/linux/signal.h > > index ea91abe..0ae3388 100644 > > --- a/include/linux/signal.h > > +++ b/include/linux/signal.h > > @@ -237,12 +237,15 @@ extern int group_send_sig_info(int sig, struct siginfo *info, struct task_struct > > extern int __group_send_sig_info(int, struct siginfo *, struct task_struct *); > > extern long do_sigpending(void __user *, unsigned long); > > extern int sigprocmask(int, sigset_t *, sigset_t *); > > +extern int show_unhandled_signals; > > > > struct pt_regs; > > extern int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka, struct pt_regs *regs, void *cookie); > > > > extern struct kmem_cache *sighand_cachep; > > > > +int unhandled_signal(struct task_struct *tsk, int sig); > > + > > /* > > * In POSIX a signal is sent either to a specific thread (Linux task) > > * or to the process as a whole (Linux thread group). How the signal > > diff --git a/kernel/signal.c b/kernel/signal.c > > index 39d1227..ef8156a 100644 > > --- a/kernel/signal.c > > +++ b/kernel/signal.c > > @@ -255,6 +255,16 @@ flush_signal_handlers(struct task_struct *t, int force_default) > > } > > } > > > > +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); > > +} > > + > > > > /* Notify the system that a driver wants to block all signals for this > > * process, and wants to be notified if any signals at all were to be > > diff --git a/kernel/sysctl.c b/kernel/sysctl.c > > index 7063ebc..af7002f 100644 > > --- a/kernel/sysctl.c > > +++ b/kernel/sysctl.c > > @@ -1153,6 +1153,16 @@ static ctl_table fs_table[] = { > > }; > > > > static ctl_table debug_table[] = { > > +#ifdef CONFIG_X86 > > + { > > + .ctl_name = CTL_UNNUMBERED, > > + .procname = "exception-trace", > > + .data = &show_unhandled_signals, > > + .maxlen = sizeof(int), > > + .mode = 0644, > > + .proc_handler = proc_dointvec > > + }, > > +#endif > > { .ctl_name = 0 } > > }; > > > > - > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > Please read the FAQ at http://www.tux.org/lkml/ > > > >