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authorJessica Yu <jeyu@kernel.org>2018-01-10 00:51:24 +0100
committerIngo Molnar <mingo@kernel.org>2018-02-16 09:12:58 +0100
commit297f9233b53a08fd457815e19f1d6f2c3389857b (patch)
treea69f719f75c4e11a8fea600b1f92ea0ee25d6d0a
parent12310e3437554328bcd75186cf331bc712cb30b2 (diff)
downloadlinux-stericsson-297f9233b53a08fd457815e19f1d6f2c3389857b.tar.gz
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>
-rw-r--r--kernel/kprobes.c78
1 files changed, 53 insertions, 25 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 2d988141ab85..102160ff5c66 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1011,23 +1011,27 @@ err_ftrace:
}
/* 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;
- kprobe_ftrace_enabled--;
- if (kprobe_ftrace_enabled == 0) {
+ if (kprobe_ftrace_enabled == 1) {
ret = unregister_ftrace_function(&kprobe_ftrace_ops);
- WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
+ if (WARN(ret < 0, "Failed to unregister kprobe-ftrace (%d)\n", ret))
+ return ret;
}
+
+ kprobe_ftrace_enabled--;
+
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 @@ already_enabled:
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;