[1/2] tracing: kprobe: Fix potential null-ptr-deref on trace_event_file in kprobe_event_gen_test_exit()
Commit Message
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>
---
kernel/trace/kprobe_event_gen_test.c | 44 ++++++++++++++++++----------
1 file changed, 28 insertions(+), 16 deletions(-)
Comments
On Mon, 7 Nov 2022 15:16:16 +0800
Shang XiaoJing <shangxiaojing@huawei.com> wrote:
> 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")
Ah, indeed. If anything wrong in the test code and if the
gen_kprobe_test/gen_kretprobe_test is not initialized, this
can happen.
Cc: stable@vger.kernel.org
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Thank you!
> Signed-off-by: Shang XiaoJing <shangxiaojing@huawei.com>
> ---
> 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
>
On 2022/11/7 21:25, Masami Hiramatsu (Google) wrote:
> On Mon, 7 Nov 2022 15:16:16 +0800
> Shang XiaoJing <shangxiaojing@huawei.com> wrote:
>
>> 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")
>
> Ah, indeed. If anything wrong in the test code and if the
> gen_kprobe_test/gen_kretprobe_test is not initialized, this
> can happen.
>
> Cc: stable@vger.kernel.org
> Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
>
> Thank you!
>
Thanks for the review, will add the Tag in v2.
Thanks,
@@ -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"));