[for-linus][PATCH 1/8] kprobes: Fix to check probe enabled before disarm_kprobe_ftrace()

[for-linus][PATCH 1/8] kprobes: Fix to check probe enabled before disarm_kprobe_ftrace()

[Steven Rostedt]

From: Masami Hiramatsu <mhiramat@kernel.org>

Commit 0cb2f1372baa ("kprobes: Fix NULL pointer dereference at
kprobe_ftrace_handler") fixed one bug but not completely fixed yet.
If we run a kprobe_module.tc of ftracetest, kernel showed a warning
as below.

# ./ftracetest test.d/kprobe/kprobe_module.tc
=== Ftrace unit tests ===
[1] Kprobe dynamic event - probing module
...
[   22.400215] ------------[ cut here ]------------
[   22.400962] Failed to disarm kprobe-ftrace at trace_printk_irq_work+0x0/0x7e [trace_printk] (-2)
[   22.402139] WARNING: CPU: 7 PID: 200 at kernel/kprobes.c:1091 __disarm_kprobe_ftrace.isra.0+0x7e/0xa0
[   22.403358] Modules linked in: trace_printk(-)
[   22.404028] CPU: 7 PID: 200 Comm: rmmod Not tainted 5.9.0-rc2+ #66
[   22.404870] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014
[   22.406139] RIP: 0010:__disarm_kprobe_ftrace.isra.0+0x7e/0xa0
[   22.406947] Code: 30 8b 03 eb c9 80 3d e5 09 1f 01 00 75 dc 49 8b 34 24 89 c2 48 c7 c7 a0 c2 05 82 89 45 e4 c6 05 cc 09 1f 01 01 e8 a9 c7 f0 ff <0f> 0b 8b 45 e4 eb b9 89 c6 48 c7 c7 70 c2 05 82 89 45 e4 e8 91 c7
[   22.409544] RSP: 0018:ffffc90000237df0 EFLAGS: 00010286
[   22.410385] RAX: 0000000000000000 RBX: ffffffff83066024 RCX: 0000000000000000
[   22.411434] RDX: 0000000000000001 RSI: ffffffff810de8d3 RDI: ffffffff810de8d3
[   22.412687] RBP: ffffc90000237e10 R08: 0000000000000001 R09: 0000000000000001
[   22.413762] R10: 0000000000000000 R11: 0000000000000001 R12: ffff88807c478640
[   22.414852] R13: ffffffff8235ebc0 R14: ffffffffa00060c0 R15: 0000000000000000
[   22.415941] FS:  00000000019d48c0(0000) GS:ffff88807d7c0000(0000) knlGS:0000000000000000
[   22.417264] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   22.418176] CR2: 00000000005bb7e3 CR3: 0000000078f7a000 CR4: 00000000000006a0
[   22.419309] Call Trace:
[   22.419990]  kill_kprobe+0x94/0x160
[   22.420652]  kprobes_module_callback+0x64/0x230
[   22.421470]  notifier_call_chain+0x4f/0x70
[   22.422184]  blocking_notifier_call_chain+0x49/0x70
[   22.422979]  __x64_sys_delete_module+0x1ac/0x240
[   22.423733]  do_syscall_64+0x38/0x50
[   22.424366]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[   22.425176] RIP: 0033:0x4bb81d
[   22.425741] Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e0 ff ff ff f7 d8 64 89 01 48
[   22.428726] RSP: 002b:00007ffc70fef008 EFLAGS: 00000246 ORIG_RAX: 00000000000000b0
[   22.430169] RAX: ffffffffffffffda RBX: 00000000019d48a0 RCX: 00000000004bb81d
[   22.431375] RDX: 0000000000000000 RSI: 0000000000000880 RDI: 00007ffc70fef028
[   22.432543] RBP: 0000000000000880 R08: 00000000ffffffff R09: 00007ffc70fef320
[   22.433692] R10: 0000000000656300 R11: 0000000000000246 R12: 00007ffc70fef028
[   22.434635] R13: 0000000000000000 R14: 0000000000000002 R15: 0000000000000000
[   22.435682] irq event stamp: 1169
[   22.436240] hardirqs last  enabled at (1179): [<ffffffff810df542>] console_unlock+0x422/0x580
[   22.437466] hardirqs last disabled at (1188): [<ffffffff810df19b>] console_unlock+0x7b/0x580
[   22.438608] softirqs last  enabled at (866): [<ffffffff81c0038e>] __do_softirq+0x38e/0x490
[   22.439637] softirqs last disabled at (859): [<ffffffff81a00f42>] asm_call_on_stack+0x12/0x20
[   22.440690] ---[ end trace 1e7ce7e1e4567276 ]---
[   22.472832] trace_kprobe: This probe might be able to register after target module is loaded. Continue.

This is because the kill_kprobe() calls disarm_kprobe_ftrace() even
if the given probe is not enabled. In that case, ftrace_set_filter_ip()
fails because the given probe point is not registered to ftrace.

Fix to check the given (going) probe is enabled before invoking
disarm_kprobe_ftrace().

Link: https://lkml.kernel.org/r/159888672694.1411785.5987998076694782591.stgit@devnote2

Fixes: 0cb2f1372baa ("kprobes: Fix NULL pointer dereference at kprobe_ftrace_handler")
Cc: Ingo Molnar <mingo@kernel.org>
Cc: "Naveen N . Rao" <naveen.n.rao@linux.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: David Miller <davem@davemloft.net>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Chengming Zhou <zhouchengming@bytedance.com>
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/kprobes.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 287b263c9cb9..d43b48ecdb4f 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -2159,9 +2159,10 @@ static void kill_kprobe(struct kprobe *p)
 
 	/*
 	 * The module is going away. We should disarm the kprobe which
-	 * is using ftrace.
+	 * is using ftrace, because ftrace framework is still available at
+	 * MODULE_STATE_GOING notification.
 	 */
-	if (kprobe_ftrace(p))
+	if (kprobe_ftrace(p) && !kprobe_disabled(p) && !kprobes_all_disarmed)
 		disarm_kprobe_ftrace(p);
 }
 
-- 
2.28.0

[for-linus][PATCH 6/8] tracing: fix double free

[Steven Rostedt]

From: Tom Rix <trix@redhat.com>

clang static analyzer reports this problem

trace_events_hist.c:3824:3: warning: Attempt to free
  released memory
    kfree(hist_data->attrs->var_defs.name[i]);

In parse_var_defs() if there is a problem allocating
var_defs.expr, the earlier var_defs.name is freed.
This free is duplicated by free_var_defs() which frees
the rest of the list.

Because free_var_defs() has to run anyway, remove the
second free fom parse_var_defs().

Link: https://lkml.kernel.org/r/20200907135845.15804-1-trix@redhat.com

Cc: stable@vger.kernel.org
Fixes: 30350d65ac56 ("tracing: Add variable support to hist triggers")
Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace_events_hist.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 0b933546142e..1b2ef6490229 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -3865,7 +3865,6 @@ static int parse_var_defs(struct hist_trigger_data *hist_data)
 
 			s = kstrdup(field_str, GFP_KERNEL);
 			if (!s) {
-				kfree(hist_data->attrs->var_defs.name[n_vars]);
 				ret = -ENOMEM;
 				goto free;
 			}
-- 
2.28.0

[for-linus][PATCH 7/8] kprobes: tracing/kprobes: Fix to kill kprobes on initmem after boot

[Steven Rostedt]

From: Masami Hiramatsu <mhiramat@kernel.org>

Since kprobe_event= cmdline option allows user to put kprobes on the
functions in initmem, kprobe has to make such probes gone after boot.
Currently the probes on the init functions in modules will be handled
by module callback, but the kernel init text isn't handled.
Without this, kprobes may access non-exist text area to disable or
remove it.

Link: https://lkml.kernel.org/r/159972810544.428528.1839307531600646955.stgit@devnote2

Fixes: 970988e19eb0 ("tracing/kprobe: Add kprobe_event= boot parameter")
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 include/linux/kprobes.h |  5 +++++
 init/main.c             |  2 ++
 kernel/kprobes.c        | 22 ++++++++++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 9be1bff4f586..8aab327b5539 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -373,6 +373,8 @@ void unregister_kretprobes(struct kretprobe **rps, int num);
 void kprobe_flush_task(struct task_struct *tk);
 void recycle_rp_inst(struct kretprobe_instance *ri, struct hlist_head *head);
 
+void kprobe_free_init_mem(void);
+
 int disable_kprobe(struct kprobe *kp);
 int enable_kprobe(struct kprobe *kp);
 
@@ -435,6 +437,9 @@ static inline void unregister_kretprobes(struct kretprobe **rps, int num)
 static inline void kprobe_flush_task(struct task_struct *tk)
 {
 }
+static inline void kprobe_free_init_mem(void)
+{
+}
 static inline int disable_kprobe(struct kprobe *kp)
 {
 	return -ENOSYS;
diff --git a/init/main.c b/init/main.c
index ae78fb68d231..038128b2a755 100644
--- a/init/main.c
+++ b/init/main.c
@@ -33,6 +33,7 @@
 #include <linux/nmi.h>
 #include <linux/percpu.h>
 #include <linux/kmod.h>
+#include <linux/kprobes.h>
 #include <linux/vmalloc.h>
 #include <linux/kernel_stat.h>
 #include <linux/start_kernel.h>
@@ -1402,6 +1403,7 @@ static int __ref kernel_init(void *unused)
 	kernel_init_freeable();
 	/* need to finish all async __init code before freeing the memory */
 	async_synchronize_full();
+	kprobe_free_init_mem();
 	ftrace_free_init_mem();
 	free_initmem();
 	mark_readonly();
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index d43b48ecdb4f..d750e025d1ff 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -2453,6 +2453,28 @@ static struct notifier_block kprobe_module_nb = {
 extern unsigned long __start_kprobe_blacklist[];
 extern unsigned long __stop_kprobe_blacklist[];
 
+void kprobe_free_init_mem(void)
+{
+	void *start = (void *)(&__init_begin);
+	void *end = (void *)(&__init_end);
+	struct hlist_head *head;
+	struct kprobe *p;
+	int i;
+
+	mutex_lock(&kprobe_mutex);
+
+	/* Kill all kprobes on initmem */
+	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
+		head = &kprobe_table[i];
+		hlist_for_each_entry(p, head, hlist) {
+			if (start <= (void *)p->addr && (void *)p->addr < end)
+				kill_kprobe(p);
+		}
+	}
+
+	mutex_unlock(&kprobe_mutex);
+}
+
 static int __init init_kprobes(void)
 {
 	int i, err = 0;
-- 
2.28.0