Re: [PATCH net 1/2] bpf: set maximum number of attached progs to 64 for a single perf tp

[Yonghong Song]

On 11/30/17 6:07 PM, Daniel Borkmann wrote:

On 11/30/2017 10:47 PM, Yonghong Song wrote:

cgropu+bpf prog array has a maximum number of 64 programs.
Let us apply the same limit here.

Signed-off-by: Yonghong Song 


Both applied to bpf tree, thanks! Please add a proper Fixes tags in the
future; took care of it this time.


Will try to remember next time :-).
Thanks for taking care of this!

Re: [PATCH net 1/2] bpf: set maximum number of attached progs to 64 for a single perf tp

[Daniel Borkmann]

On 11/30/2017 10:47 PM, Yonghong Song wrote:
> cgropu+bpf prog array has a maximum number of 64 programs.
> Let us apply the same limit here.
> 
> Signed-off-by: Yonghong Song 

Both applied to bpf tree, thanks! Please add a proper Fixes tags in the
future; took care of it this time.

[PATCH net 1/2] bpf: set maximum number of attached progs to 64 for a single perf tp

[Yonghong Song]

cgropu+bpf prog array has a maximum number of 64 programs.
Let us apply the same limit here.

Signed-off-by: Yonghong Song 
---
 kernel/bpf/core.c| 3 ++-
 kernel/trace/bpf_trace.c | 8 
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index b9f8686..86b50aa 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1447,7 +1447,8 @@ int bpf_prog_array_length(struct bpf_prog_array __rcu 
*progs)
rcu_read_lock();
prog = rcu_dereference(progs)->progs;
for (; *prog; prog++)
-   cnt++;
+   if (*prog != _bpf_prog.prog)
+   cnt++;
rcu_read_unlock();
return cnt;
 }
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 27d1f4f..0ce99c3 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -759,6 +759,8 @@ const struct bpf_prog_ops perf_event_prog_ops = {
 
 static DEFINE_MUTEX(bpf_event_mutex);
 
+#define BPF_TRACE_MAX_PROGS 64
+
 int perf_event_attach_bpf_prog(struct perf_event *event,
   struct bpf_prog *prog)
 {
@@ -772,6 +774,12 @@ int perf_event_attach_bpf_prog(struct perf_event *event,
goto unlock;
 
old_array = event->tp_event->prog_array;
+   if (old_array &&
+   bpf_prog_array_length(old_array) >= BPF_TRACE_MAX_PROGS) {
+   ret = -E2BIG;
+   goto unlock;
+   }
+
ret = bpf_prog_array_copy(old_array, NULL, prog, _array);
if (ret < 0)
goto unlock;
-- 
2.9.5