Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753473AbaFDXW4 (ORCPT ); Wed, 4 Jun 2014 19:22:56 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:40335 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753395AbaFDXWx (ORCPT ); Wed, 4 Jun 2014 19:22:53 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Helge Deller Subject: [PATCH 3.14 167/228] parisc: ratelimit userspace segfault printing Date: Wed, 4 Jun 2014 16:23:16 -0700 Message-Id: <20140604232353.395534804@linuxfoundation.org> X-Mailer: git-send-email 1.9.0 In-Reply-To: <20140604232347.966798903@linuxfoundation.org> References: <20140604232347.966798903@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Helge Deller commit fef47e2a2e1e75fe50a10f634a80f16808348cc6 upstream. Ratelimit printing of userspace segfaults and make it runtime configurable via the /proc/sys/debug/exception-trace variable. This should resolve syslog from growing way too fast and thus prevents possible system service attacks. Signed-off-by: Helge Deller Signed-off-by: Greg Kroah-Hartman --- arch/parisc/Kconfig | 1 arch/parisc/kernel/traps.c | 54 ++++++++++++++++++++------------------------- arch/parisc/mm/fault.c | 44 +++++++++++++++++++++++++----------- 3 files changed, 56 insertions(+), 43 deletions(-) --- a/arch/parisc/Kconfig +++ b/arch/parisc/Kconfig @@ -22,6 +22,7 @@ config PARISC select GENERIC_SMP_IDLE_THREAD select GENERIC_STRNCPY_FROM_USER select SYSCTL_ARCH_UNALIGN_ALLOW + select SYSCTL_EXCEPTION_TRACE select HAVE_MOD_ARCH_SPECIFIC select VIRT_TO_BUS select MODULES_USE_ELF_RELA --- a/arch/parisc/kernel/traps.c +++ b/arch/parisc/kernel/traps.c @@ -25,6 +25,7 @@ #include #include #include +#include #include #include @@ -42,9 +43,6 @@ #include "../math-emu/math-emu.h" /* for handle_fpe() */ -#define PRINT_USER_FAULTS /* (turn this on if you want user faults to be */ - /* dumped to the console via printk) */ - #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) DEFINE_SPINLOCK(pa_dbit_lock); #endif @@ -160,6 +158,17 @@ void show_regs(struct pt_regs *regs) } } +static DEFINE_RATELIMIT_STATE(_hppa_rs, + DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST); + +#define parisc_printk_ratelimited(critical, regs, fmt, ...) { \ + if ((critical || show_unhandled_signals) && __ratelimit(&_hppa_rs)) { \ + printk(fmt, ##__VA_ARGS__); \ + show_regs(regs); \ + } \ +} + + static void do_show_stack(struct unwind_frame_info *info) { int i = 1; @@ -229,12 +238,10 @@ void die_if_kernel(char *str, struct pt_ if (err == 0) return; /* STFU */ - printk(KERN_CRIT "%s (pid %d): %s (code %ld) at " RFMT "\n", + parisc_printk_ratelimited(1, regs, + KERN_CRIT "%s (pid %d): %s (code %ld) at " RFMT "\n", current->comm, task_pid_nr(current), str, err, regs->iaoq[0]); -#ifdef PRINT_USER_FAULTS - /* XXX for debugging only */ - show_regs(regs); -#endif + return; } @@ -321,14 +328,11 @@ static void handle_break(struct pt_regs (tt == BUG_TRAP_TYPE_NONE) ? 9 : 0); } -#ifdef PRINT_USER_FAULTS - if (unlikely(iir != GDB_BREAK_INSN)) { - printk(KERN_DEBUG "break %d,%d: pid=%d command='%s'\n", + if (unlikely(iir != GDB_BREAK_INSN)) + parisc_printk_ratelimited(0, regs, + KERN_DEBUG "break %d,%d: pid=%d command='%s'\n", iir & 31, (iir>>13) & ((1<<13)-1), task_pid_nr(current), current->comm); - show_regs(regs); - } -#endif /* send standard GDB signal */ handle_gdb_break(regs, TRAP_BRKPT); @@ -758,11 +762,9 @@ void notrace handle_interruption(int cod default: if (user_mode(regs)) { -#ifdef PRINT_USER_FAULTS - printk(KERN_DEBUG "\nhandle_interruption() pid=%d command='%s'\n", - task_pid_nr(current), current->comm); - show_regs(regs); -#endif + parisc_printk_ratelimited(0, regs, KERN_DEBUG + "handle_interruption() pid=%d command='%s'\n", + task_pid_nr(current), current->comm); /* SIGBUS, for lack of a better one. */ si.si_signo = SIGBUS; si.si_code = BUS_OBJERR; @@ -779,16 +781,10 @@ void notrace handle_interruption(int cod if (user_mode(regs)) { if ((fault_space >> SPACEID_SHIFT) != (regs->sr[7] >> SPACEID_SHIFT)) { -#ifdef PRINT_USER_FAULTS - if (fault_space == 0) - printk(KERN_DEBUG "User Fault on Kernel Space "); - else - printk(KERN_DEBUG "User Fault (long pointer) (fault %d) ", - code); - printk(KERN_CONT "pid=%d command='%s'\n", - task_pid_nr(current), current->comm); - show_regs(regs); -#endif + parisc_printk_ratelimited(0, regs, KERN_DEBUG + "User fault %d on space 0x%08lx, pid=%d command='%s'\n", + code, fault_space, + task_pid_nr(current), current->comm); si.si_signo = SIGSEGV; si.si_errno = 0; si.si_code = SEGV_MAPERR; --- a/arch/parisc/mm/fault.c +++ b/arch/parisc/mm/fault.c @@ -19,10 +19,6 @@ #include #include -#define PRINT_USER_FAULTS /* (turn this on if you want user faults to be */ - /* dumped to the console via printk) */ - - /* Various important other fields */ #define bit22set(x) (x & 0x00000200) #define bits23_25set(x) (x & 0x000001c0) @@ -34,6 +30,8 @@ DEFINE_PER_CPU(struct exception_data, exception_data); +int show_unhandled_signals = 1; + /* * parisc_acctyp(unsigned int inst) -- * Given a PA-RISC memory access instruction, determine if the @@ -173,6 +171,32 @@ int fixup_exception(struct pt_regs *regs return 0; } +/* + * Print out info about fatal segfaults, if the show_unhandled_signals + * sysctl is set: + */ +static inline void +show_signal_msg(struct pt_regs *regs, unsigned long code, + unsigned long address, struct task_struct *tsk, + struct vm_area_struct *vma) +{ + if (!unhandled_signal(tsk, SIGSEGV)) + return; + + if (!printk_ratelimit()) + return; + + pr_warn("\n"); + pr_warn("do_page_fault() command='%s' type=%lu address=0x%08lx", + tsk->comm, code, address); + print_vma_addr(KERN_CONT " in ", regs->iaoq[0]); + if (vma) + pr_warn(" vm_start = 0x%08lx, vm_end = 0x%08lx\n", + vma->vm_start, vma->vm_end); + + show_regs(regs); +} + void do_page_fault(struct pt_regs *regs, unsigned long code, unsigned long address) { @@ -270,16 +294,8 @@ bad_area: if (user_mode(regs)) { struct siginfo si; -#ifdef PRINT_USER_FAULTS - printk(KERN_DEBUG "\n"); - printk(KERN_DEBUG "do_page_fault() pid=%d command='%s' type=%lu address=0x%08lx\n", - task_pid_nr(tsk), tsk->comm, code, address); - if (vma) { - printk(KERN_DEBUG "vm_start = 0x%08lx, vm_end = 0x%08lx\n", - vma->vm_start, vma->vm_end); - } - show_regs(regs); -#endif + show_signal_msg(regs, code, address, tsk, vma); + switch (code) { case 15: /* Data TLB miss fault/Data page fault */ /* send SIGSEGV when outside of vma */ -- 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/