On Mon, Aug 31, 2020 at 11:12 PM Masami Hiramatsu <mhira...@kernel.org> wrote: > > Commit 0cb2f1372baa ("kprobes: Fix NULL pointer dereference at > kprobe_ftrace_handler") fixed one bug but not completely fixed yet. > If we run a kprobe_module.tc of ftracetest, kernel showed a warning > as below. > > > # ./ftracetest test.d/kprobe/kprobe_module.tc > === Ftrace unit tests === > [1] Kprobe dynamic event - probing module > ... > [ 22.400215] ------------[ cut here ]------------ > [ 22.400962] Failed to disarm kprobe-ftrace at > trace_printk_irq_work+0x0/0x7e [trace_printk] (-2) > [ 22.402139] WARNING: CPU: 7 PID: 200 at kernel/kprobes.c:1091 > __disarm_kprobe_ftrace.isra.0+0x7e/0xa0 > [ 22.403358] Modules linked in: trace_printk(-) > [ 22.404028] CPU: 7 PID: 200 Comm: rmmod Not tainted 5.9.0-rc2+ #66 > [ 22.404870] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS > 1.13.0-1ubuntu1 04/01/2014 > [ 22.406139] RIP: 0010:__disarm_kprobe_ftrace.isra.0+0x7e/0xa0 > [ 22.406947] Code: 30 8b 03 eb c9 80 3d e5 09 1f 01 00 75 dc 49 8b 34 24 89 > c2 48 c7 c7 a0 c2 05 82 89 45 e4 c6 05 cc 09 1f 01 01 e8 a9 c7 f0 ff <0f> 0b > 8b 45 e4 eb b9 89 c6 48 c7 c7 70 c2 05 82 89 45 e4 e8 91 c7 > [ 22.409544] RSP: 0018:ffffc90000237df0 EFLAGS: 00010286 > [ 22.410385] RAX: 0000000000000000 RBX: ffffffff83066024 RCX: > 0000000000000000 > [ 22.411434] RDX: 0000000000000001 RSI: ffffffff810de8d3 RDI: > ffffffff810de8d3 > [ 22.412687] RBP: ffffc90000237e10 R08: 0000000000000001 R09: > 0000000000000001 > [ 22.413762] R10: 0000000000000000 R11: 0000000000000001 R12: > ffff88807c478640 > [ 22.414852] R13: ffffffff8235ebc0 R14: ffffffffa00060c0 R15: > 0000000000000000 > [ 22.415941] FS: 00000000019d48c0(0000) GS:ffff88807d7c0000(0000) > knlGS:0000000000000000 > [ 22.417264] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 22.418176] CR2: 00000000005bb7e3 CR3: 0000000078f7a000 CR4: > 00000000000006a0 > [ 22.419309] Call Trace: > [ 22.419990] kill_kprobe+0x94/0x160 > [ 22.420652] kprobes_module_callback+0x64/0x230 > [ 22.421470] notifier_call_chain+0x4f/0x70 > [ 22.422184] blocking_notifier_call_chain+0x49/0x70 > [ 22.422979] __x64_sys_delete_module+0x1ac/0x240 > [ 22.423733] do_syscall_64+0x38/0x50 > [ 22.424366] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > [ 22.425176] RIP: 0033:0x4bb81d > [ 22.425741] Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 > f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d > 01 f0 ff ff 73 01 c3 48 c7 c1 e0 ff ff ff f7 d8 64 89 01 48 > [ 22.428726] RSP: 002b:00007ffc70fef008 EFLAGS: 00000246 ORIG_RAX: > 00000000000000b0 > [ 22.430169] RAX: ffffffffffffffda RBX: 00000000019d48a0 RCX: > 00000000004bb81d > [ 22.431375] RDX: 0000000000000000 RSI: 0000000000000880 RDI: > 00007ffc70fef028 > [ 22.432543] RBP: 0000000000000880 R08: 00000000ffffffff R09: > 00007ffc70fef320 > [ 22.433692] R10: 0000000000656300 R11: 0000000000000246 R12: > 00007ffc70fef028 > [ 22.434635] R13: 0000000000000000 R14: 0000000000000002 R15: > 0000000000000000 > [ 22.435682] irq event stamp: 1169 > [ 22.436240] hardirqs last enabled at (1179): [<ffffffff810df542>] > console_unlock+0x422/0x580 > [ 22.437466] hardirqs last disabled at (1188): [<ffffffff810df19b>] > console_unlock+0x7b/0x580 > [ 22.438608] softirqs last enabled at (866): [<ffffffff81c0038e>] > __do_softirq+0x38e/0x490 > [ 22.439637] softirqs last disabled at (859): [<ffffffff81a00f42>] > asm_call_on_stack+0x12/0x20 > [ 22.440690] ---[ end trace 1e7ce7e1e4567276 ]--- > [ 22.472832] trace_kprobe: This probe might be able to register after > target module is loaded. Continue. > > > This is because the kill_kprobe() calls disarm_kprobe_ftrace() even > if the given probe is not enabled. In that case, ftrace_set_filter_ip() > fails because the given probe point is not registered to ftrace.
Does the following patch solve this issue? Thanks. kprobes: Fix kill kprobe which has been marked as gone https://lkml.org/lkml/2020/8/19/1496 > > Fix to check the given (going) probe is enabled before invoking > disarm_kprobe_ftrace(). > > Fixes: 0cb2f1372baa ("kprobes: Fix NULL pointer dereference at > kprobe_ftrace_handler") > Cc: sta...@vger.kernel.org > Signed-off-by: Masami Hiramatsu <mhira...@kernel.org> > --- > kernel/kprobes.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index 287b263c9cb9..d43b48ecdb4f 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -2159,9 +2159,10 @@ static void kill_kprobe(struct kprobe *p) > > /* > * The module is going away. We should disarm the kprobe which > - * is using ftrace. > + * is using ftrace, because ftrace framework is still available at > + * MODULE_STATE_GOING notification. > */ > - if (kprobe_ftrace(p)) > + if (kprobe_ftrace(p) && !kprobe_disabled(p) && !kprobes_all_disarmed) > disarm_kprobe_ftrace(p); > } > > -- Yours, Muchun