From fef47e2a2e1e75fe50a10f634a80f16808348cc6 Mon Sep 17 00:00:00 2001
From: Helge Deller <deller@gmx.de>
Date: Mon, 5 May 2014 18:07:12 +0200
Subject: parisc: ratelimit userspace segfault printing

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 <deller@gmx.de>
Cc: stable@vger.kernel.org # 3.13+
---
 arch/parisc/mm/fault.c | 44 ++++++++++++++++++++++++++++++--------------
 1 file changed, 30 insertions(+), 14 deletions(-)

(limited to 'arch/parisc/mm')

diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c
index 9d08c71a967e..d72197f0ddb8 100644
--- a/arch/parisc/mm/fault.c
+++ b/arch/parisc/mm/fault.c
@@ -19,10 +19,6 @@
 #include <asm/uaccess.h>
 #include <asm/traps.h>
 
-#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 */
-- 
cgit v1.2.3