From: David Faust <david.faust@oracle.com>
Date: Thu, 7 Nov 2024 17:27:07 +0000 (-0800)
Subject: bpf: avoid possible null deref in btf_ext_output [PR target/117447]
X-Git-Tag: basepoints/gcc-16~4527
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0e1382034246a594f1da8dbaee97c4a06743f31a;p=thirdparty%2Fgcc.git

bpf: avoid possible null deref in btf_ext_output [PR target/117447]

The BPF-specific .BTF.ext section is always generated for BPF programs
if -gbtf is specified, and generating it requires BTF information and
assumes that the BTF info has already been generated.

Compiling non-C languages to BPF is not supported, nor is generating
CTF/BTF for non-C.  But, compiling another language like C++ to BPF
with -gbtf specified meant that we would try to generate the .BTF.ext
section anyway, and then ICE because no BTF information was available.

Add a check to bail out of btf_ext_output if the TU CTFC does not exist,
meaning no BTF info is available.

gcc/
	PR target/117447
	* config/bpf/btfext-out.cc (btf_ext_output): Bail if TU CTFC is null.
---

diff --git a/gcc/config/bpf/btfext-out.cc b/gcc/config/bpf/btfext-out.cc
index ca6241aa52ee..760b2b59ff6a 100644
--- a/gcc/config/bpf/btfext-out.cc
+++ b/gcc/config/bpf/btfext-out.cc
@@ -611,6 +611,9 @@ btf_ext_init (void)
 void
 btf_ext_output (void)
 {
+  if (!ctf_get_tu_ctfc ())
+    return;
+
   output_btfext_header ();
   output_btfext_func_info (btf_ext);
   if (TARGET_BPF_CORE)