[3.13.y.z extended stable] Patch "parisc: ratelimit userspace segfault printing" has been added to staging queue
Kamal Mostafa
kamal at canonical.com
Tue Jun 17 21:42:23 UTC 2014
This is a note to let you know that I have just added a patch titled
parisc: ratelimit userspace segfault printing
to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree
which can be found at:
http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue
This patch is scheduled to be released in version 3.13.11.4.
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Kamal
------
>From 14a2c96418aeb9742dedd4c2fa54f54be4f72113 Mon Sep 17 00:00:00 2001
From: Helge Deller <deller at gmx.de>
Date: Mon, 5 May 2014 18:07:12 +0200
Subject: parisc: ratelimit userspace segfault printing
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 <deller at gmx.de>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
arch/parisc/Kconfig | 1 +
arch/parisc/kernel/traps.c | 54 +++++++++++++++++++++-------------------------
arch/parisc/mm/fault.c | 44 +++++++++++++++++++++++++------------
3 files changed, 56 insertions(+), 43 deletions(-)
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index b5f1858..2142ec2 100644
--- 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
diff --git a/arch/parisc/kernel/traps.c b/arch/parisc/kernel/traps.c
index 1cd1d0c..47ee620 100644
--- a/arch/parisc/kernel/traps.c
+++ b/arch/parisc/kernel/traps.c
@@ -25,6 +25,7 @@
#include <linux/interrupt.h>
#include <linux/console.h>
#include <linux/bug.h>
+#include <linux/ratelimit.h>
#include <asm/assembly.h>
#include <asm/uaccess.h>
@@ -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_regs *regs, long err)
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 *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 code, struct pt_regs *regs)
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 code, struct pt_regs *regs)
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;
diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c
index 9d08c71..d72197f 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 */
--
1.9.1
More information about the kernel-team
mailing list