Messages in this thread | | | Date | Tue, 17 Sep 2019 08:56:43 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH] tracing/kprobe: Fix NULL pointer access in trace_porbe_unlink() |
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On Tue, 17 Sep 2019 14:11:37 +0900 Masami Hiramatsu <mhiramat@kernel.org> wrote:
> Fix NULL pointer access in trace_probe_unlink() by initializing > trace_probe.list correctly in trace_probe_init(). > > In the error case of trace_probe_init(), it can call trace_probe_unlink() > before initializing trace_probe.list member. This causes NULL pointer > dereference at list_del_init() in trace_probe_unlink(). > > Syzbot reported : > > kasan: CONFIG_KASAN_INLINE enabled > kasan: GPF could be caused by NULL-ptr deref or user memory access > general protection fault: 0000 [#1] PREEMPT SMP KASAN > CPU: 1 PID: 8633 Comm: syz-executor797 Not tainted 5.3.0-rc8-next-20190915 > #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > RIP: 0010:__list_del_entry_valid+0x85/0xf5 lib/list_debug.c:51 > Code: 0f 84 e1 00 00 00 48 b8 22 01 00 00 00 00 ad de 49 39 c4 0f 84 e2 00 > 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <80> 3c 02 00 75 > 53 49 8b 14 24 4c 39 f2 0f 85 99 00 00 00 49 8d 7d > RSP: 0018:ffff888090a7f9d8 EFLAGS: 00010246 > RAX: dffffc0000000000 RBX: ffff88809b6f90c0 RCX: ffffffff817c0ca9 > RDX: 0000000000000000 RSI: ffffffff817c0a73 RDI: ffff88809b6f90c8 > RBP: ffff888090a7f9f0 R08: ffff88809a04e600 R09: ffffed1015d26aed > R10: ffffed1015d26aec R11: ffff8880ae935763 R12: 0000000000000000 > R13: 0000000000000000 R14: ffff88809b6f90c0 R15: ffff88809b6f90d0 > FS: 0000555556f99880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00000000006cc090 CR3: 00000000962b2000 CR4: 00000000001406e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > __list_del_entry include/linux/list.h:131 [inline] > list_del_init include/linux/list.h:190 [inline] > trace_probe_unlink+0x1f/0x200 kernel/trace/trace_probe.c:959 > trace_probe_cleanup+0xd3/0x110 kernel/trace/trace_probe.c:973 > trace_probe_init+0x3f2/0x510 kernel/trace/trace_probe.c:1011 > alloc_trace_uprobe+0x5e/0x250 kernel/trace/trace_uprobe.c:353 > create_local_trace_uprobe+0x109/0x4a0 kernel/trace/trace_uprobe.c:1508 > perf_uprobe_init+0x131/0x210 kernel/trace/trace_event_perf.c:314 > perf_uprobe_event_init+0x106/0x1a0 kernel/events/core.c:8898 > perf_try_init_event+0x135/0x590 kernel/events/core.c:10184 > perf_init_event kernel/events/core.c:10228 [inline] > perf_event_alloc.part.0+0x1b89/0x33d0 kernel/events/core.c:10505 > perf_event_alloc kernel/events/core.c:10887 [inline] > __do_sys_perf_event_open+0xa2d/0x2d00 kernel/events/core.c:10989 > __se_sys_perf_event_open kernel/events/core.c:10871 [inline] > __x64_sys_perf_event_open+0xbe/0x150 kernel/events/core.c:10871 > do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > Reported-by: syzbot+2f807f4d3a2a4e87f18f@syzkaller.appspotmail.com > Fixes: ca89bc071d5e ("tracing/kprobe: Add multi-probe per event support") > Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Thanks Masami. I was just about to get my pull request to Linus out, but will now add this and start running my tests with it.
-- Steve
> --- > kernel/trace/trace_probe.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c > index 1e67fef06e53..baf58a3612c0 100644 > --- a/kernel/trace/trace_probe.c > +++ b/kernel/trace/trace_probe.c > @@ -986,6 +986,12 @@ int trace_probe_init(struct trace_probe *tp, const char *event, > if (!tp->event) > return -ENOMEM; > > + INIT_LIST_HEAD(&tp->event->files); > + INIT_LIST_HEAD(&tp->event->class.fields); > + INIT_LIST_HEAD(&tp->event->probes); > + INIT_LIST_HEAD(&tp->list); > + list_add(&tp->event->probes, &tp->list); > + > call = trace_probe_event_call(tp); > call->class = &tp->event->class; > call->name = kstrdup(event, GFP_KERNEL); > @@ -999,11 +1005,6 @@ int trace_probe_init(struct trace_probe *tp, const char *event, > ret = -ENOMEM; > goto error; > } > - INIT_LIST_HEAD(&tp->event->files); > - INIT_LIST_HEAD(&tp->event->class.fields); > - INIT_LIST_HEAD(&tp->event->probes); > - INIT_LIST_HEAD(&tp->list); > - list_add(&tp->event->probes, &tp->list); > > return 0; >
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