Messages in this thread Patch in this message | | | Date | Mon, 7 Nov 2022 22:38:35 +0900 | From | Masami Hiramatsu (Google) <> | Subject | Re: [PATCH 2/2] tracing: kprobe: Fix potential null-ptr-deref on trace_array in kprobe_event_gen_test_exit() |
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Hi,
On Mon, 7 Nov 2022 15:16:17 +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->tr to NULL > after called kprobe_event_delete() and add NULL check when releasing > the module. > > 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> > --- > kernel/trace/kprobe_event_gen_test.c | 29 +++++++++++++++++----------- > 1 file changed, 18 insertions(+), 11 deletions(-) > > diff --git a/kernel/trace/kprobe_event_gen_test.c b/kernel/trace/kprobe_event_gen_test.c > index 1c98fafcf333..277e21e4a63e 100644 > --- a/kernel/trace/kprobe_event_gen_test.c > +++ b/kernel/trace/kprobe_event_gen_test.c > @@ -145,6 +145,8 @@ static int __init test_gen_kprobe_cmd(void) > delete: > /* We got an error after creating the event, delete it */ > ret = kprobe_event_delete("gen_kprobe_test"); > + if (trace_event_file_is_valid(gen_kprobe_test)) > + gen_kprobe_test->tr = NULL;
I think the correct fix should be
if (trace_event_file_is_valid(gen_kprobe_test)) { trace_put_event_file(gen_kprobe_test); gen_kprobe_test = NULL; } ret = kprobe_event_delete("gen_kprobe_test");
Since the gen_kprobe_event is owned by ftrace subsystem, the test code should not change the tr field.
> goto out; > } > > @@ -208,6 +210,8 @@ static int __init test_gen_kretprobe_cmd(void) > delete: > /* We got an error after creating the event, delete it */ > ret = kprobe_event_delete("gen_kretprobe_test"); > + if (trace_event_file_is_valid(gen_kretprobe_test)) > + gen_kretprobe_test->tr = NULL;
Ditto.
And then, below changes are not required.
Thank you,
> goto out; > } > > @@ -222,9 +226,10 @@ static int __init kprobe_event_gen_test_init(void) > ret = test_gen_kretprobe_cmd(); > if (ret) { > 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)); > + if (gen_kretprobe_test->tr) > + 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")); > @@ -236,10 +241,11 @@ static int __init kprobe_event_gen_test_init(void) > static void __exit kprobe_event_gen_test_exit(void) > { > 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)); > + if (gen_kprobe_test->tr) > + /* 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); > @@ -250,10 +256,11 @@ static void __exit kprobe_event_gen_test_exit(void) > WARN_ON(kprobe_event_delete("gen_kprobe_test")); > > 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)); > + if (gen_kretprobe_test->tr) > + /* 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); > -- > 2.17.1 >
-- Masami Hiramatsu (Google) <mhiramat@kernel.org>
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