Messages in this thread | | | Date | Mon, 7 Nov 2022 23:50:44 +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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On Mon, 7 Nov 2022 21:47:10 +0800 shangxiaojing <shangxiaojing@huawei.com> wrote:
> Hi, > > On 2022/11/7 21:38, Masami Hiramatsu (Google) wrote: > > 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. > > > When trace_array_set_clr_event() failed, it already called > trace_put_event_file(), maybe we only need set gen_kprobe_test to NULL.
Ah, OK. That should work.
Thank you,
> > >> 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. > > Yes, will fix in v2, thanks for the review. > > Thanks, > -- > Shang XiaoJing
-- Masami Hiramatsu (Google) <mhiramat@kernel.org>
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