Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753186AbXFIEF7 (ORCPT ); Sat, 9 Jun 2007 00:05:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751130AbXFIEFv (ORCPT ); Sat, 9 Jun 2007 00:05:51 -0400 Received: from smtp-out.google.com ([216.239.45.13]:31918 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750924AbXFIEFu (ORCPT ); Sat, 9 Jun 2007 00:05:50 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=received:date:to:cc:subject:message-id:mime-version: content-type:content-disposition:user-agent:from; b=PAi7MEGFURVD64XLi4hN174WeEnw9byr5MkYNUm8nNmeGv8EmTqKcIhO92sQv0Xgx /wBONvNHAEg2X8t5hnkJw== Date: Fri, 8 Jun 2007 21:05:43 -0700 To: akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org Subject: [PATCH] Make i386 kernel show the unhandled signals Message-ID: <20070609040542.GA20357@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.11 From: masouds@google.com (Masoud Asgharifard Sharbiani) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 10411 Lines: 318 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 different kernels. Like x86_64, it can be disabled by setting debug.show_unhandled_signals sysctl variable to 0 (or by doing echo 0 > /proc/sys/debug/show_unhandled_signals) 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; } cheers, Masoud Signed-off-by: Masoud Sharbiani arch/i386/kernel/signal.c | 5 +++++ arch/i386/kernel/traps.c | 7 +++++++ arch/i386/mm/fault.c | 11 +++++++++++ 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 +++ include/linux/sysctl.h | 3 +++ kernel/signal.c | 10 ++++++++++ kernel/sysctl.c | 10 ++++++++++ 12 files changed, 57 insertions(+), 52 deletions(-) diff --git a/arch/i386/kernel/signal.c b/arch/i386/kernel/signal.c index d574e38..828dcb0 100644 --- a/arch/i386/kernel/signal.c +++ b/arch/i386/kernel/signal.c @@ -199,6 +199,11 @@ asmlinkage int sys_sigreturn(unsigned long __unused) return eax; badframe: + if (show_unhandled_signals && printk_ratelimit()) + printk("%s[%d] bad frame in sigreturn frame:%p eip:%lx esp:%lx oeax:%lx\n", + 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 90da057..bccc5b4 100644 --- a/arch/i386/kernel/traps.c +++ b/arch/i386/kernel/traps.c @@ -610,6 +610,13 @@ 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 29d7d61..2aa4206 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 @@ -465,6 +467,15 @@ 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/i386/mm/init.c b/arch/i386/mm/init.c 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 cb29fb9..4f46b4d 100644 --- a/arch/x86_64/kernel/traps.c +++ b/arch/x86_64/kernel/traps.c @@ -577,7 +577,8 @@ 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, @@ -681,7 +682,8 @@ 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 bfb62a1..73917cf 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, @@ -489,7 +479,8 @@ 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 1ad5111..19a6f5b 100644 --- a/arch/x86_64/mm/init.c +++ b/arch/x86_64/mm/init.c @@ -690,41 +690,6 @@ 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 9a5eac5..aa2c243 100644 --- a/include/linux/signal.h +++ b/include/linux/signal.h @@ -238,12 +238,15 @@ 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/include/linux/sysctl.h b/include/linux/sysctl.h index 47f1c53..a4fd7f1 100644 --- a/include/linux/sysctl.h +++ b/include/linux/sysctl.h @@ -835,6 +835,9 @@ enum { }; /* CTL_DEBUG names: */ +enum { + DEBUG_UNHANDLED_SIGNALS = 1, +}; /* CTL_DEV names: */ enum { diff --git a/kernel/signal.c b/kernel/signal.c index fe590e0..ce6085f 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 30ee462..9486870 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1026,6 +1026,16 @@ static ctl_table fs_table[] = { }; static ctl_table debug_table[] = { +#ifdef CONFIG_X86 + { + .ctl_name = DEBUG_UNHANDLED_SIGNALS, + .procname = "show-unhandled-signals", + .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/