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kprobes: Propagate error from disarm_kprobe_ftrace() 

Improve error handling when disarming ftrace-based kprobes. Like with
arm_kprobe_ftrace(), propagate any errors from disarm_kprobe_ftrace() so
that we do not disable/unregister kprobes that are still armed. In other
words, unregister_kprobe() and disable_kprobe() should not report success
if the kprobe could not be disarmed.

disarm_all_kprobes() keeps its current behavior and attempts to
disarm all kprobes. It returns the last encountered error and gives a
warning if not all probes could be disarmed.

This patch is based on Petr Mladek's original patchset (patches 2 and 3)
back in 2015, which improved kprobes error handling, found here:

   https://lkml.org/lkml/2015/2/26/452

However, further work on this had been paused since then and the patches
were not upstreamed.

Based-on-patches-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: David S . Miller <davem@davemloft.net>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/20180109235124.30886-3-jeyu@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Jessica Yu 2018-01-10 00:51:24 +01:00 committed by Ingo Molnar
parent 12310e3437
commit 297f9233b5
1 changed files with 54 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

80
kernel/kprobes.c
View File

@ -1011,23 +1011,27 @@ static int arm_kprobe_ftrace(struct kprobe *p)
}
/* Caller must lock kprobe_mutex */
static void disarm_kprobe_ftrace(struct kprobe *p)
static int disarm_kprobe_ftrace(struct kprobe *p)
{
int ret;
int ret = 0;
if (kprobe_ftrace_enabled == 1) {
ret = unregister_ftrace_function(&kprobe_ftrace_ops);
if (WARN(ret < 0, "Failed to unregister kprobe-ftrace (%d)\n", ret))
return ret;
}
kprobe_ftrace_enabled--;
if (kprobe_ftrace_enabled == 0) {
ret = unregister_ftrace_function(&kprobe_ftrace_ops);
WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
}
ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
(unsigned long)p->addr, 1, 0);
WARN(ret < 0, "Failed to disarm kprobe-ftrace at %p (%d)\n", p->addr, ret);
return ret;
}
#else /* !CONFIG_KPROBES_ON_FTRACE */
#define prepare_kprobe(p) arch_prepare_kprobe(p)
#define arm_kprobe_ftrace(p) (-ENODEV)
#define disarm_kprobe_ftrace(p) do {} while (0)
#define disarm_kprobe_ftrace(p) (-ENODEV)
#endif
/* Arm a kprobe with text_mutex */
@ -1046,18 +1050,18 @@ static int arm_kprobe(struct kprobe *kp)
}
/* Disarm a kprobe with text_mutex */
static void disarm_kprobe(struct kprobe *kp, bool reopt)
static int disarm_kprobe(struct kprobe *kp, bool reopt)
{
if (unlikely(kprobe_ftrace(kp))) {
disarm_kprobe_ftrace(kp);
return;
}
if (unlikely(kprobe_ftrace(kp)))
return disarm_kprobe_ftrace(kp);
cpus_read_lock();
mutex_lock(&text_mutex);
__disarm_kprobe(kp, reopt);
mutex_unlock(&text_mutex);
cpus_read_unlock();
return 0;
}
/*
@ -1639,11 +1643,12 @@ static int aggr_kprobe_disabled(struct kprobe *ap)
static struct kprobe *__disable_kprobe(struct kprobe *p)
{
struct kprobe *orig_p;
int ret;
/* Get an original kprobe for return */
orig_p = __get_valid_kprobe(p);
if (unlikely(orig_p == NULL))
return NULL;
return ERR_PTR(-EINVAL);
if (!kprobe_disabled(p)) {
/* Disable probe if it is a child probe */
@ -1657,8 +1662,13 @@ static struct kprobe *__disable_kprobe(struct kprobe *p)
* should have already been disarmed, so
* skip unneed disarming process.
*/
if (!kprobes_all_disarmed)
disarm_kprobe(orig_p, true);
if (!kprobes_all_disarmed) {
ret = disarm_kprobe(orig_p, true);
if (ret) {
p->flags &= ~KPROBE_FLAG_DISABLED;
return ERR_PTR(ret);
}
}
orig_p->flags |= KPROBE_FLAG_DISABLED;
}
}
@ -1675,8 +1685,8 @@ static int __unregister_kprobe_top(struct kprobe *p)
/* Disable kprobe. This will disarm it if needed. */
ap = __disable_kprobe(p);
if (ap == NULL)
return -EINVAL;
if (IS_ERR(ap))
return PTR_ERR(ap);
if (ap == p)
/*
@ -2109,12 +2119,14 @@ static void kill_kprobe(struct kprobe *p)
int disable_kprobe(struct kprobe *kp)
{
int ret = 0;
struct kprobe *p;
mutex_lock(&kprobe_mutex);
/* Disable this kprobe */
if (__disable_kprobe(kp) == NULL)
ret = -EINVAL;
p = __disable_kprobe(kp);
if (IS_ERR(p))
ret = PTR_ERR(p);
mutex_unlock(&kprobe_mutex);
return ret;
@ -2486,34 +2498,50 @@ static int arm_all_kprobes(void)
return ret;
}
static void disarm_all_kprobes(void)
static int disarm_all_kprobes(void)
{
struct hlist_head *head;
struct kprobe *p;
unsigned int i;
unsigned int i, total = 0, errors = 0;
int err, ret = 0;
mutex_lock(&kprobe_mutex);
/* If kprobes are already disarmed, just return */
if (kprobes_all_disarmed) {
mutex_unlock(&kprobe_mutex);
return;
return 0;
}
kprobes_all_disarmed = true;
printk(KERN_INFO "Kprobes globally disabled\n");
for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
head = &kprobe_table[i];
/* Disarm all kprobes on a best-effort basis */
hlist_for_each_entry_rcu(p, head, hlist) {
if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
disarm_kprobe(p, false);
if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p)) {
err = disarm_kprobe(p, false);
if (err) {
errors++;
ret = err;
}
total++;
}
}
}
if (errors)
pr_warn("Kprobes globally disabled, but failed to disarm %d out of %d probes\n",
errors, total);
else
pr_info("Kprobes globally disabled\n");
mutex_unlock(&kprobe_mutex);
/* Wait for disarming all kprobes by optimizer */
wait_for_kprobe_optimizer();
return ret;
}
/*
@ -2556,7 +2584,7 @@ static ssize_t write_enabled_file_bool(struct file *file,
case 'n':
case 'N':
case '0':
disarm_all_kprobes();
ret = disarm_all_kprobes();
break;
default:
return -EINVAL;