Currently the __uprobe_register will return 0 (success) when called with
negative offset. The reason is that the call to register_for_each_vma and
then build_map_info won't return error for negative offset. They just won't
do anything - no matching vma is found so there's no registered breakpoint
for the uprobe.
I don't think we can change the behaviour of __uprobe_register and fail
for negative uprobe offset, because apps might depend on that already.
But I think we can still make the change and check for it on bpf multi
link syscall level.
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---
kernel/trace/bpf_trace.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 774cf476a892..0dbf8d9b3ace 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -3397,6 +3397,11 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
goto error_free;
}
+ if (uprobes[i].offset < 0) {
+ err = -EINVAL;
+ goto error_free;
+ }
+
uprobes[i].link = link;
if (flags & BPF_F_UPROBE_MULTI_RETURN)
--
2.43.0
