[for-linus][PATCH 1/6] ring-buffer: Check for NULL cpu_buffer in ring_buffer_wake_waiters()

[for-linus][PATCH 1/6] ring-buffer: Check for NULL cpu_buffer in ring_buffer_wake_waiters()

[Steven Rostedt]

From: "Steven Rostedt (Google)" <rostedt@goodmis.org>

On some machines the number of listed CPUs may be bigger than the actual
CPUs that exist. The tracing subsystem allocates a per_cpu directory with
access to the per CPU ring buffer via a cpuX file. But to save space, the
ring buffer will only allocate buffers for online CPUs, even though the
CPU array will be as big as the nr_cpu_ids.

With the addition of waking waiters on the ring buffer when closing the
file, the ring_buffer_wake_waiters() now needs to make sure that the
buffer is allocated (with the irq_work allocated with it) before trying to
wake waiters, as it will cause a NULL pointer dereference.

While debugging this, I added a NULL check for the buffer itself (which is
OK to do), and also NULL pointer checks against buffer->buffers (which is
not fine, and will WARN) as well as making sure the CPU number passed in
is within the nr_cpu_ids (which is also not fine if it isn't).

Link: https://lore.kernel.org/all/87h6zklb6n.wl-tiwai@suse.de/
Link: https://lore.kernel.org/all/CAM6Wdxc0KRJMXVAA0Y=u6Jh2V=uWB-_Fn6M4xRuNppfXzL1mUg@mail.gmail.com/
Link: https://lkml.kernel.org/linux-trace-kernel/20221101191009.1e7378c8@rorschach.local.home

Cc: stable@vger.kernel.org
Cc: Steven Noonan <steven.noonan@gmail.com>
Bugzilla: https://bugzilla.opensuse.org/show_bug.cgi?id=1204705
Reported-by: Takashi Iwai <tiwai@suse.de>
Reported-by: Roland Ruckerbauer <roland.rucky@gmail.com>
Fixes: f3ddb74ad079 ("tracing: Wake up ring buffer waiters on closing of the file")
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/ring_buffer.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 199759c73519..9712083832f4 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -937,6 +937,9 @@ void ring_buffer_wake_waiters(struct trace_buffer *buffer, int cpu)
 	struct ring_buffer_per_cpu *cpu_buffer;
 	struct rb_irq_work *rbwork;
 
+	if (!buffer)
+		return;
+
 	if (cpu == RING_BUFFER_ALL_CPUS) {
 
 		/* Wake up individual ones too. One level recursion */
@@ -945,7 +948,15 @@ void ring_buffer_wake_waiters(struct trace_buffer *buffer, int cpu)
 
 		rbwork = &buffer->irq_work;
 	} else {
+		if (WARN_ON_ONCE(!buffer->buffers))
+			return;
+		if (WARN_ON_ONCE(cpu >= nr_cpu_ids))
+			return;
+
 		cpu_buffer = buffer->buffers[cpu];
+		/* The CPU buffer may not have been initialized yet */
+		if (!cpu_buffer)
+			return;
 		rbwork = &cpu_buffer->irq_work;
 	}
 
-- 
2.35.1

[for-linus][PATCH 2/6] ftrace: Fix use-after-free for dynamic ftrace_ops

[Steven Rostedt]

From: Li Huafei <lihuafei1@huawei.com>

KASAN reported a use-after-free with ftrace ops [1]. It was found from
vmcore that perf had registered two ops with the same content
successively, both dynamic. After unregistering the second ops, a
use-after-free occurred.

In ftrace_shutdown(), when the second ops is unregistered, the
FTRACE_UPDATE_CALLS command is not set because there is another enabled
ops with the same content.  Also, both ops are dynamic and the ftrace
callback function is ftrace_ops_list_func, so the
FTRACE_UPDATE_TRACE_FUNC command will not be set. Eventually the value
of 'command' will be 0 and ftrace_shutdown() will skip the rcu
synchronization.

However, ftrace may be activated. When the ops is released, another CPU
may be accessing the ops.  Add the missing synchronization to fix this
problem.

[1]
BUG: KASAN: use-after-free in __ftrace_ops_list_func kernel/trace/ftrace.c:7020 [inline]
BUG: KASAN: use-after-free in ftrace_ops_list_func+0x2b0/0x31c kernel/trace/ftrace.c:7049
Read of size 8 at addr ffff56551965bbc8 by task syz-executor.2/14468

CPU: 1 PID: 14468 Comm: syz-executor.2 Not tainted 5.10.0 #7
Hardware name: linux,dummy-virt (DT)
Call trace:
 dump_backtrace+0x0/0x40c arch/arm64/kernel/stacktrace.c:132
 show_stack+0x30/0x40 arch/arm64/kernel/stacktrace.c:196
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1b4/0x248 lib/dump_stack.c:118
 print_address_description.constprop.0+0x28/0x48c mm/kasan/report.c:387
 __kasan_report mm/kasan/report.c:547 [inline]
 kasan_report+0x118/0x210 mm/kasan/report.c:564
 check_memory_region_inline mm/kasan/generic.c:187 [inline]
 __asan_load8+0x98/0xc0 mm/kasan/generic.c:253
 __ftrace_ops_list_func kernel/trace/ftrace.c:7020 [inline]
 ftrace_ops_list_func+0x2b0/0x31c kernel/trace/ftrace.c:7049
 ftrace_graph_call+0x0/0x4
 __might_sleep+0x8/0x100 include/linux/perf_event.h:1170
 __might_fault mm/memory.c:5183 [inline]
 __might_fault+0x58/0x70 mm/memory.c:5171
 do_strncpy_from_user lib/strncpy_from_user.c:41 [inline]
 strncpy_from_user+0x1f4/0x4b0 lib/strncpy_from_user.c:139
 getname_flags+0xb0/0x31c fs/namei.c:149
 getname+0x2c/0x40 fs/namei.c:209
 [...]

Allocated by task 14445:
 kasan_save_stack+0x24/0x50 mm/kasan/common.c:48
 kasan_set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc mm/kasan/common.c:479 [inline]
 __kasan_kmalloc.constprop.0+0x110/0x13c mm/kasan/common.c:449
 kasan_kmalloc+0xc/0x14 mm/kasan/common.c:493
 kmem_cache_alloc_trace+0x440/0x924 mm/slub.c:2950
 kmalloc include/linux/slab.h:563 [inline]
 kzalloc include/linux/slab.h:675 [inline]
 perf_event_alloc.part.0+0xb4/0x1350 kernel/events/core.c:11230
 perf_event_alloc kernel/events/core.c:11733 [inline]
 __do_sys_perf_event_open kernel/events/core.c:11831 [inline]
 __se_sys_perf_event_open+0x550/0x15f4 kernel/events/core.c:11723
 __arm64_sys_perf_event_open+0x6c/0x80 kernel/events/core.c:11723
 [...]

Freed by task 14445:
 kasan_save_stack+0x24/0x50 mm/kasan/common.c:48
 kasan_set_track+0x24/0x34 mm/kasan/common.c:56
 kasan_set_free_info+0x20/0x40 mm/kasan/generic.c:358
 __kasan_slab_free.part.0+0x11c/0x1b0 mm/kasan/common.c:437
 __kasan_slab_free mm/kasan/common.c:445 [inline]
 kasan_slab_free+0x2c/0x40 mm/kasan/common.c:446
 slab_free_hook mm/slub.c:1569 [inline]
 slab_free_freelist_hook mm/slub.c:1608 [inline]
 slab_free mm/slub.c:3179 [inline]
 kfree+0x12c/0xc10 mm/slub.c:4176
 perf_event_alloc.part.0+0xa0c/0x1350 kernel/events/core.c:11434
 perf_event_alloc kernel/events/core.c:11733 [inline]
 __do_sys_perf_event_open kernel/events/core.c:11831 [inline]
 __se_sys_perf_event_open+0x550/0x15f4 kernel/events/core.c:11723
 [...]

Link: https://lore.kernel.org/linux-trace-kernel/20221103031010.166498-1-lihuafei1@huawei.com

Fixes: edb096e00724f ("ftrace: Fix memleak when unregistering dynamic ops when tracing disabled")
Cc: stable@vger.kernel.org
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Li Huafei <lihuafei1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/ftrace.c | 16 +++-------------
 1 file changed, 3 insertions(+), 13 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index fbf2543111c0..7dc023641bf1 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3028,18 +3028,8 @@ int ftrace_shutdown(struct ftrace_ops *ops, int command)
 		command |= FTRACE_UPDATE_TRACE_FUNC;
 	}
 
-	if (!command || !ftrace_enabled) {
-		/*
-		 * If these are dynamic or per_cpu ops, they still
-		 * need their data freed. Since, function tracing is
-		 * not currently active, we can just free them
-		 * without synchronizing all CPUs.
-		 */
-		if (ops->flags & FTRACE_OPS_FL_DYNAMIC)
-			goto free_ops;
-
-		return 0;
-	}
+	if (!command || !ftrace_enabled)
+		goto out;
 
 	/*
 	 * If the ops uses a trampoline, then it needs to be
@@ -3076,6 +3066,7 @@ int ftrace_shutdown(struct ftrace_ops *ops, int command)
 	removed_ops = NULL;
 	ops->flags &= ~FTRACE_OPS_FL_REMOVING;
 
+out:
 	/*
 	 * Dynamic ops may be freed, we must make sure that all
 	 * callers are done before leaving this function.
@@ -3103,7 +3094,6 @@ int ftrace_shutdown(struct ftrace_ops *ops, int command)
 		if (IS_ENABLED(CONFIG_PREEMPTION))
 			synchronize_rcu_tasks();
 
- free_ops:
 		ftrace_trampoline_free(ops);
 	}
 
-- 
2.35.1

[for-linus][PATCH 3/6] kprobe: reverse kp->flags when arm_kprobe failed

[Steven Rostedt]

From: Li Qiang <liq3ea@163.com>

In aggregate kprobe case, when arm_kprobe failed,
we need set the kp->flags with KPROBE_FLAG_DISABLED again.
If not, the 'kp' kprobe will been considered as enabled
but it actually not enabled.

Link: https://lore.kernel.org/all/20220902155820.34755-1-liq3ea@163.com/

Fixes: 12310e343755 ("kprobes: Propagate error from arm_kprobe_ftrace()")
Cc: stable@vger.kernel.org
Signed-off-by: Li Qiang <liq3ea@163.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
 kernel/kprobes.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 3220b0a2fb4a..cd9f5a66a690 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -2429,8 +2429,11 @@ int enable_kprobe(struct kprobe *kp)
 	if (!kprobes_all_disarmed && kprobe_disabled(p)) {
 		p->flags &= ~KPROBE_FLAG_DISABLED;
 		ret = arm_kprobe(p);
-		if (ret)
+		if (ret) {
 			p->flags |= KPROBE_FLAG_DISABLED;
+			if (p != kp)
+				kp->flags |= KPROBE_FLAG_DISABLED;
+		}
 	}
 out:
 	mutex_unlock(&kprobe_mutex);
-- 
2.35.1

[for-linus][PATCH 4/6] fprobe: Check rethook_alloc() return in rethook initialization

[Steven Rostedt]

From: Rafael Mendonca <rafaelmendsr@gmail.com>

Check if fp->rethook succeeded to be allocated. Otherwise, if
rethook_alloc() fails, then we end up dereferencing a NULL pointer in
rethook_add_node().

Link: https://lore.kernel.org/all/20221025031209.954836-1-rafaelmendsr@gmail.com/

Fixes: 5b0ab78998e3 ("fprobe: Add exit_handler support")
Cc: stable@vger.kernel.org
Signed-off-by: Rafael Mendonca <rafaelmendsr@gmail.com>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
 kernel/trace/fprobe.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index aac63ca9c3d1..71614b2a67ff 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -141,6 +141,8 @@ static int fprobe_init_rethook(struct fprobe *fp, int num)
 		return -E2BIG;
 
 	fp->rethook = rethook_alloc((void *)fp, fprobe_exit_handler);
+	if (!fp->rethook)
+		return -ENOMEM;
 	for (i = 0; i < size; i++) {
 		struct fprobe_rethook_node *node;
 
-- 
2.35.1

[for-linus][PATCH 5/6] tracing/fprobe: Fix to check whether fprobe is registered correctly

[Steven Rostedt]

From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>

Since commit ab51e15d535e ("fprobe: Introduce FPROBE_FL_KPROBE_SHARED flag
for fprobe") introduced fprobe_kprobe_handler() for fprobe::ops::func,
unregister_fprobe() fails to unregister the registered if user specifies
FPROBE_FL_KPROBE_SHARED flag.
Moreover, __register_ftrace_function() is possible to change the
ftrace_ops::func, thus we have to check fprobe::ops::saved_func instead.

To check it correctly, it should confirm the fprobe::ops::saved_func is
either fprobe_handler() or fprobe_kprobe_handler().

Link: https://lore.kernel.org/all/166677683946.1459107.15997653945538644683.stgit@devnote3/

Fixes: cad9931f64dc ("fprobe: Add ftrace based probe APIs")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
 kernel/trace/fprobe.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index 71614b2a67ff..e8143e368074 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -303,7 +303,8 @@ int unregister_fprobe(struct fprobe *fp)
 {
 	int ret;
 
-	if (!fp || fp->ops.func != fprobe_handler)
+	if (!fp || (fp->ops.saved_func != fprobe_handler &&
+		    fp->ops.saved_func != fprobe_kprobe_handler))
 		return -EINVAL;
 
 	/*
-- 
2.35.1

[for-linus][PATCH 6/6] tracing: kprobe: Fix memory leak in test_gen_kprobe/kretprobe_cmd()

[Steven Rostedt]

From: Shang XiaoJing <shangxiaojing@huawei.com>

test_gen_kprobe_cmd() only free buf in fail path, hence buf will leak
when there is no failure. Move kfree(buf) from fail path to common path
to prevent the memleak. The same reason and solution in
test_gen_kretprobe_cmd().

unreferenced object 0xffff888143b14000 (size 2048):
  comm "insmod", pid 52490, jiffies 4301890980 (age 40.553s)
  hex dump (first 32 bytes):
    70 3a 6b 70 72 6f 62 65 73 2f 67 65 6e 5f 6b 70  p:kprobes/gen_kp
    72 6f 62 65 5f 74 65 73 74 20 64 6f 5f 73 79 73  robe_test do_sys
  backtrace:
    [<000000006d7b836b>] kmalloc_trace+0x27/0xa0
    [<0000000009528b5b>] 0xffffffffa059006f
    [<000000008408b580>] do_one_initcall+0x87/0x2a0
    [<00000000c4980a7e>] do_init_module+0xdf/0x320
    [<00000000d775aad0>] load_module+0x3006/0x3390
    [<00000000e9a74b80>] __do_sys_finit_module+0x113/0x1b0
    [<000000003726480d>] do_syscall_64+0x35/0x80
    [<000000003441e93b>] entry_SYSCALL_64_after_hwframe+0x46/0xb0

Link: https://lore.kernel.org/all/20221102072954.26555-1-shangxiaojing@huawei.com/

Fixes: 64836248dda2 ("tracing: Add kprobe event command generation test module")
Cc: stable@vger.kernel.org
Signed-off-by: Shang XiaoJing <shangxiaojing@huawei.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
 kernel/trace/kprobe_event_gen_test.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/kernel/trace/kprobe_event_gen_test.c b/kernel/trace/kprobe_event_gen_test.c
index 80e04a1e1977..d81f7c51025c 100644
--- a/kernel/trace/kprobe_event_gen_test.c
+++ b/kernel/trace/kprobe_event_gen_test.c
@@ -100,20 +100,20 @@ static int __init test_gen_kprobe_cmd(void)
 					 KPROBE_GEN_TEST_FUNC,
 					 KPROBE_GEN_TEST_ARG0, KPROBE_GEN_TEST_ARG1);
 	if (ret)
-		goto free;
+		goto out;
 
 	/* Use kprobe_event_add_fields to add the rest of the fields */
 
 	ret = kprobe_event_add_fields(&cmd, KPROBE_GEN_TEST_ARG2, KPROBE_GEN_TEST_ARG3);
 	if (ret)
-		goto free;
+		goto out;
 
 	/*
 	 * This actually creates the event.
 	 */
 	ret = kprobe_event_gen_cmd_end(&cmd);
 	if (ret)
-		goto free;
+		goto out;
 
 	/*
 	 * Now get the gen_kprobe_test event file.  We need to prevent
@@ -136,13 +136,11 @@ static int __init test_gen_kprobe_cmd(void)
 		goto delete;
 	}
  out:
+	kfree(buf);
 	return ret;
  delete:
 	/* We got an error after creating the event, delete it */
 	ret = kprobe_event_delete("gen_kprobe_test");
- free:
-	kfree(buf);
-
 	goto out;
 }
 
@@ -170,14 +168,14 @@ static int __init test_gen_kretprobe_cmd(void)
 					    KPROBE_GEN_TEST_FUNC,
 					    "$retval");
 	if (ret)
-		goto free;
+		goto out;
 
 	/*
 	 * This actually creates the event.
 	 */
 	ret = kretprobe_event_gen_cmd_end(&cmd);
 	if (ret)
-		goto free;
+		goto out;
 
 	/*
 	 * Now get the gen_kretprobe_test event file.  We need to
@@ -201,13 +199,11 @@ static int __init test_gen_kretprobe_cmd(void)
 		goto delete;
 	}
  out:
+	kfree(buf);
 	return ret;
  delete:
 	/* We got an error after creating the event, delete it */
 	ret = kprobe_event_delete("gen_kretprobe_test");
- free:
-	kfree(buf);
-
 	goto out;
 }
 
-- 
2.35.1