Properly zero initialize uprobe opts sz member

This change fixes the sz member initialization of bpf_uprobe_opts
objects that we use in the uprobe attach code. The previously incorrect
size could lead to libbpf failing the attachment on optimized builds,
where the size of Program objects was different to dev ones.

Fixes: #447
Signed-off-by: Daniel Müller <[email protected]>

Author: d-e-s-o

libbpf-rs/CHANGELOG.md

@@ -6,6 +6,8 @@ Unreleased
   capabilities
 - Fixed issue where instances of `Map` created or opened without going through
   `Object` would leak file descriptors
+- Fixed potential Uprobe attachment failures on optimized builds caused by
+  improper `libbpf_sys::bpf_object_open_opts` object initialization
 - Adjusted various methods to work with `BorrowedFd` instead of raw file
   descriptors
 - Made `RingBufferBuilder::add` enforce that `self` cannot outlive the maps

libbpf-rs/src/program.rs

@@ -5,8 +5,8 @@ use std::os::unix::io::AsFd;
 use std::os::unix::io::AsRawFd;
 use std::os::unix::io::BorrowedFd;
 use std::path::Path;
+use std::ptr;
 use std::ptr::NonNull;
-use std::ptr::{self};
 
 use libbpf_sys::bpf_func_id;
 use num_enum::TryFromPrimitive;
@@ -545,7 +545,7 @@ impl Program {
 
         let func_name = util::str_to_cstring(&func_name)?;
         let opts = libbpf_sys::bpf_uprobe_opts {
-            sz: mem::size_of::<Self>() as u64,
+            sz: mem::size_of::<libbpf_sys::bpf_uprobe_opts>() as _,
             ref_ctr_offset: ref_ctr_offset as libbpf_sys::size_t,
             bpf_cookie: cookie,
             retprobe,

libbpf-rs/src/util.rs

@@ -80,7 +80,7 @@ pub fn create_bpf_entity_checked<B: 'static, F: FnOnce() -> *mut B>(f: F) -> Res
                                            //
                                            // One way to fix the bug might be to change to calling
                                            // create_bpf_entity_checked_opt and handling Ok(None)
-                                           // as a meaningfull value.
+                                           // as a meaningful value.
             ))
         })
     })