[PATCH v2 0/2] tracing: kprobe: Fix some bug in kprobe_event_gen_test.c

[PATCH v2 0/2] tracing: kprobe: Fix some bug in kprobe_event_gen_test.c

[Shang XiaoJing]

Due to lack of the checking and setting-NULL on pointer, there are some
null pointer dereference or page fault bugs were found when insert
module, and fixed by this patch set. 

---
changes in v2:
- add cc tag.
- improvement on patch 2.

Shang XiaoJing (2):
  tracing: kprobe: Fix potential null-ptr-deref on trace_event_file in
    kprobe_event_gen_test_exit()
  tracing: kprobe: Fix potential null-ptr-deref on trace_array in
    kprobe_event_gen_test_exit()

 kernel/trace/kprobe_event_gen_test.c | 48 ++++++++++++++++++----------
 1 file changed, 32 insertions(+), 16 deletions(-)

-- 
2.17.1

[PATCH v2 1/2] tracing: kprobe: Fix potential null-ptr-deref on trace_event_file in kprobe_event_gen_test_exit()

[Shang XiaoJing]

When trace_get_event_file() failed, gen_kretprobe_test will be assigned
as the error code. If module kprobe_event_gen_test is removed now, the
null pointer dereference will happen in kprobe_event_gen_test_exit().
Check if gen_kprobe_test or gen_kretprobe_test is error code or NULL
before dereference them.

BUG: kernel NULL pointer dereference, address: 0000000000000012
PGD 0 P4D 0
Oops: 0000 [#1] SMP PTI
CPU: 3 PID: 2210 Comm: modprobe Not tainted
6.1.0-rc1-00171-g2159299a3b74-dirty #217
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.15.0-0-g2dd4b9b3f840-prebuilt.qemu.org 04/01/2014
RIP: 0010:kprobe_event_gen_test_exit+0x1c/0xb5 [kprobe_event_gen_test]
Code: Unable to access opcode bytes at 0xffffffff9ffffff2.
RSP: 0018:ffffc900015bfeb8 EFLAGS: 00010246
RAX: ffffffffffffffea RBX: ffffffffa0002080 RCX: 0000000000000000
RDX: ffffffffa0001054 RSI: ffffffffa0001064 RDI: ffffffffdfc6349c
RBP: ffffffffa0000000 R08: 0000000000000004 R09: 00000000001e95c0
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000800
R13: ffffffffa0002420 R14: 0000000000000000 R15: 0000000000000000
FS:  00007f56b75be540(0000) GS:ffff88813bc00000(0000)
knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffff9ffffff2 CR3: 000000010874a006 CR4: 0000000000330ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __x64_sys_delete_module+0x206/0x380
 ? lockdep_hardirqs_on_prepare+0xd8/0x190
 ? syscall_enter_from_user_mode+0x1c/0x50
 do_syscall_64+0x3f/0x90
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Fixes: 64836248dda2 ("tracing: Add kprobe event command generation test module")
Signed-off-by: Shang XiaoJing <shangxiaojing@huawei.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: stable@vger.kernel.org
---
changes in v2:
- add Cc tag to stable@vger.kernel.org.
---
 kernel/trace/kprobe_event_gen_test.c | 44 ++++++++++++++++++----------
 1 file changed, 28 insertions(+), 16 deletions(-)

diff --git a/kernel/trace/kprobe_event_gen_test.c b/kernel/trace/kprobe_event_gen_test.c
index d81f7c51025c..1c98fafcf333 100644
--- a/kernel/trace/kprobe_event_gen_test.c
+++ b/kernel/trace/kprobe_event_gen_test.c
@@ -73,6 +73,10 @@ static struct trace_event_file *gen_kretprobe_test;
 #define KPROBE_GEN_TEST_ARG3	NULL
 #endif
 
+static bool trace_event_file_is_valid(struct trace_event_file *input)
+{
+	return input && !IS_ERR(input);
+}
 
 /*
  * Test to make sure we can create a kprobe event, then add more
@@ -217,10 +221,12 @@ static int __init kprobe_event_gen_test_init(void)
 
 	ret = test_gen_kretprobe_cmd();
 	if (ret) {
-		WARN_ON(trace_array_set_clr_event(gen_kretprobe_test->tr,
-						  "kprobes",
-						  "gen_kretprobe_test", false));
-		trace_put_event_file(gen_kretprobe_test);
+		if (trace_event_file_is_valid(gen_kretprobe_test)) {
+			WARN_ON(trace_array_set_clr_event(gen_kretprobe_test->tr,
+							  "kprobes",
+							  "gen_kretprobe_test", false));
+			trace_put_event_file(gen_kretprobe_test);
+		}
 		WARN_ON(kprobe_event_delete("gen_kretprobe_test"));
 	}
 
@@ -229,24 +235,30 @@ static int __init kprobe_event_gen_test_init(void)
 
 static void __exit kprobe_event_gen_test_exit(void)
 {
-	/* Disable the event or you can't remove it */
-	WARN_ON(trace_array_set_clr_event(gen_kprobe_test->tr,
-					  "kprobes",
-					  "gen_kprobe_test", false));
+	if (trace_event_file_is_valid(gen_kprobe_test)) {
+		/* Disable the event or you can't remove it */
+		WARN_ON(trace_array_set_clr_event(gen_kprobe_test->tr,
+						  "kprobes",
+						  "gen_kprobe_test", false));
+
+		/* Now give the file and instance back */
+		trace_put_event_file(gen_kprobe_test);
+	}
 
-	/* Now give the file and instance back */
-	trace_put_event_file(gen_kprobe_test);
 
 	/* Now unregister and free the event */
 	WARN_ON(kprobe_event_delete("gen_kprobe_test"));
 
-	/* Disable the event or you can't remove it */
-	WARN_ON(trace_array_set_clr_event(gen_kretprobe_test->tr,
-					  "kprobes",
-					  "gen_kretprobe_test", false));
+	if (trace_event_file_is_valid(gen_kretprobe_test)) {
+		/* Disable the event or you can't remove it */
+		WARN_ON(trace_array_set_clr_event(gen_kretprobe_test->tr,
+						  "kprobes",
+						  "gen_kretprobe_test", false));
+
+		/* Now give the file and instance back */
+		trace_put_event_file(gen_kretprobe_test);
+	}
 
-	/* Now give the file and instance back */
-	trace_put_event_file(gen_kretprobe_test);
 
 	/* Now unregister and free the event */
 	WARN_ON(kprobe_event_delete("gen_kretprobe_test"));
-- 
2.17.1

[PATCH v2 2/2] tracing: kprobe: Fix potential null-ptr-deref on trace_array in kprobe_event_gen_test_exit()

[Shang XiaoJing]

When test_gen_kprobe_cmd() failed after kprobe_event_gen_cmd_end(), it
will goto delete, which will call kprobe_event_delete() and release the
corresponding resource. However, the trace_array in gen_kretprobe_test
will point to the invalid resource. Set gen_kretprobe_test to NULL
after called kprobe_event_delete() to prevent null-ptr-deref.

BUG: kernel NULL pointer dereference, address: 0000000000000070
PGD 0 P4D 0
Oops: 0000 [#1] SMP PTI
CPU: 0 PID: 246 Comm: modprobe Tainted: G        W
6.1.0-rc1-00174-g9522dc5c87da-dirty #248
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.15.0-0-g2dd4b9b3f840-prebuilt.qemu.org 04/01/2014
RIP: 0010:__ftrace_set_clr_event_nolock+0x53/0x1b0
Code: e8 82 26 fc ff 49 8b 1e c7 44 24 0c ea ff ff ff 49 39 de 0f 84 3c
01 00 00 c7 44 24 18 00 00 00 00 e8 61 26 fc ff 48 8b 6b 10 <44> 8b 65
70 4c 8b 6d 18 41 f7 c4 00 02 00 00 75 2f
RSP: 0018:ffffc9000159fe00 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff88810971d268 RCX: 0000000000000000
RDX: ffff8881080be600 RSI: ffffffff811b48ff RDI: ffff88810971d058
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001
R10: ffffc9000159fe58 R11: 0000000000000001 R12: ffffffffa0001064
R13: ffffffffa000106c R14: ffff88810971d238 R15: 0000000000000000
FS:  00007f89eeff6540(0000) GS:ffff88813b600000(0000)
knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000070 CR3: 000000010599e004 CR4: 0000000000330ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __ftrace_set_clr_event+0x3e/0x60
 trace_array_set_clr_event+0x35/0x50
 ? 0xffffffffa0000000
 kprobe_event_gen_test_exit+0xcd/0x10b [kprobe_event_gen_test]
 __x64_sys_delete_module+0x206/0x380
 ? lockdep_hardirqs_on_prepare+0xd8/0x190
 ? syscall_enter_from_user_mode+0x1c/0x50
 do_syscall_64+0x3f/0x90
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f89eeb061b7

Fixes: 64836248dda2 ("tracing: Add kprobe event command generation test module")
Signed-off-by: Shang XiaoJing <shangxiaojing@huawei.com>
Cc: stable@vger.kernel.org
---
changes in v2:
- add cc tag to stable@vger.kernel.org.
- set gen_kprobe_test to NULL instead of gen_kprobe_test->tr, so as
gen_kretprobe_test.
---
 kernel/trace/kprobe_event_gen_test.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/trace/kprobe_event_gen_test.c b/kernel/trace/kprobe_event_gen_test.c
index 1c98fafcf333..c736487fc0e4 100644
--- a/kernel/trace/kprobe_event_gen_test.c
+++ b/kernel/trace/kprobe_event_gen_test.c
@@ -143,6 +143,8 @@ static int __init test_gen_kprobe_cmd(void)
 	kfree(buf);
 	return ret;
  delete:
+	if (trace_event_file_is_valid(gen_kprobe_test))
+		gen_kprobe_test = NULL;
 	/* We got an error after creating the event, delete it */
 	ret = kprobe_event_delete("gen_kprobe_test");
 	goto out;
@@ -206,6 +208,8 @@ static int __init test_gen_kretprobe_cmd(void)
 	kfree(buf);
 	return ret;
  delete:
+	if (trace_event_file_is_valid(gen_kretprobe_test))
+		gen_kretprobe_test = NULL;
 	/* We got an error after creating the event, delete it */
 	ret = kprobe_event_delete("gen_kretprobe_test");
 	goto out;
-- 
2.17.1

Re: [PATCH v2 2/2] tracing: kprobe: Fix potential null-ptr-deref on trace_array in kprobe_event_gen_test_exit()

[Masami Hiramatsu]

On Tue, 8 Nov 2022 09:51:30 +0800
Shang XiaoJing <shangxiaojing@huawei.com> wrote:

> When test_gen_kprobe_cmd() failed after kprobe_event_gen_cmd_end(), it
> will goto delete, which will call kprobe_event_delete() and release the
> corresponding resource. However, the trace_array in gen_kretprobe_test
> will point to the invalid resource. Set gen_kretprobe_test to NULL
> after called kprobe_event_delete() to prevent null-ptr-deref.
> 
> BUG: kernel NULL pointer dereference, address: 0000000000000070
> PGD 0 P4D 0
> Oops: 0000 [#1] SMP PTI
> CPU: 0 PID: 246 Comm: modprobe Tainted: G        W
> 6.1.0-rc1-00174-g9522dc5c87da-dirty #248
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> rel-1.15.0-0-g2dd4b9b3f840-prebuilt.qemu.org 04/01/2014
> RIP: 0010:__ftrace_set_clr_event_nolock+0x53/0x1b0
> Code: e8 82 26 fc ff 49 8b 1e c7 44 24 0c ea ff ff ff 49 39 de 0f 84 3c
> 01 00 00 c7 44 24 18 00 00 00 00 e8 61 26 fc ff 48 8b 6b 10 <44> 8b 65
> 70 4c 8b 6d 18 41 f7 c4 00 02 00 00 75 2f
> RSP: 0018:ffffc9000159fe00 EFLAGS: 00010293
> RAX: 0000000000000000 RBX: ffff88810971d268 RCX: 0000000000000000
> RDX: ffff8881080be600 RSI: ffffffff811b48ff RDI: ffff88810971d058
> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001
> R10: ffffc9000159fe58 R11: 0000000000000001 R12: ffffffffa0001064
> R13: ffffffffa000106c R14: ffff88810971d238 R15: 0000000000000000
> FS:  00007f89eeff6540(0000) GS:ffff88813b600000(0000)
> knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000070 CR3: 000000010599e004 CR4: 0000000000330ef0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  __ftrace_set_clr_event+0x3e/0x60
>  trace_array_set_clr_event+0x35/0x50
>  ? 0xffffffffa0000000
>  kprobe_event_gen_test_exit+0xcd/0x10b [kprobe_event_gen_test]
>  __x64_sys_delete_module+0x206/0x380
>  ? lockdep_hardirqs_on_prepare+0xd8/0x190
>  ? syscall_enter_from_user_mode+0x1c/0x50
>  do_syscall_64+0x3f/0x90
>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
> RIP: 0033:0x7f89eeb061b7
> 
> Fixes: 64836248dda2 ("tracing: Add kprobe event command generation test module")
> Signed-off-by: Shang XiaoJing <shangxiaojing@huawei.com>

This looks good to me.

Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Thank you!

> Cc: stable@vger.kernel.org
> ---
> changes in v2:
> - add cc tag to stable@vger.kernel.org.
> - set gen_kprobe_test to NULL instead of gen_kprobe_test->tr, so as
> gen_kretprobe_test.
> ---
>  kernel/trace/kprobe_event_gen_test.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/kernel/trace/kprobe_event_gen_test.c b/kernel/trace/kprobe_event_gen_test.c
> index 1c98fafcf333..c736487fc0e4 100644
> --- a/kernel/trace/kprobe_event_gen_test.c
> +++ b/kernel/trace/kprobe_event_gen_test.c
> @@ -143,6 +143,8 @@ static int __init test_gen_kprobe_cmd(void)
>  	kfree(buf);
>  	return ret;
>   delete:
> +	if (trace_event_file_is_valid(gen_kprobe_test))
> +		gen_kprobe_test = NULL;
>  	/* We got an error after creating the event, delete it */
>  	ret = kprobe_event_delete("gen_kprobe_test");
>  	goto out;
> @@ -206,6 +208,8 @@ static int __init test_gen_kretprobe_cmd(void)
>  	kfree(buf);
>  	return ret;
>   delete:
> +	if (trace_event_file_is_valid(gen_kretprobe_test))
> +		gen_kretprobe_test = NULL;
>  	/* We got an error after creating the event, delete it */
>  	ret = kprobe_event_delete("gen_kretprobe_test");
>  	goto out;
> -- 
> 2.17.1
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>

Re: [PATCH v2 2/2] tracing: kprobe: Fix potential null-ptr-deref on trace_array in kprobe_event_gen_test_exit()

[Steven Rostedt]

On Tue, 8 Nov 2022 23:38:46 +0900
Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:

> > Fixes: 64836248dda2 ("tracing: Add kprobe event command generation test module")
> > Signed-off-by: Shang XiaoJing <shangxiaojing@huawei.com>  
> 
> This looks good to me.
> 
> Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Hi Masami,

Did you want me to pull these on top of your probes/urgent branch?

I'm going through all my patches now and will be starting the testing
hopefully later this week.

-- Steve

Re: [PATCH v2 2/2] tracing: kprobe: Fix potential null-ptr-deref on trace_array in kprobe_event_gen_test_exit()

[Masami Hiramatsu]

On Wed, 16 Nov 2022 21:55:36 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Tue, 8 Nov 2022 23:38:46 +0900
> Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:
> 
> > > Fixes: 64836248dda2 ("tracing: Add kprobe event command generation test module")
> > > Signed-off-by: Shang XiaoJing <shangxiaojing@huawei.com>  
> > 
> > This looks good to me.
> > 
> > Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> 
> Hi Masami,
> 
> Did you want me to pull these on top of your probes/urgent branch?

No, I think these patches are already queued on probes/urgent :)

https://kernel.googlesource.com/pub/scm/linux/kernel/git/trace/linux-trace.git/+/210880de4e3945d0ac028894df578063205bef61

> 
> I'm going through all my patches now and will be starting the testing
> hopefully later this week.

Thanks!

> 
> -- Steve


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>

Re: [PATCH v2 2/2] tracing: kprobe: Fix potential null-ptr-deref on trace_array in kprobe_event_gen_test_exit()

[Steven Rostedt]

On Thu, 17 Nov 2022 16:14:53 +0900
Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:

> No, I think these patches are already queued on probes/urgent :)
> 
> https://kernel.googlesource.com/pub/scm/linux/kernel/git/trace/linux-trace.git/+/210880de4e3945d0ac028894df578063205bef61

Bah, for some reason, when I searched the git log of that branch, it didn't
show up :-/

-- Steve