From: Serhei Makarov <smakarov@redhat.com>
Date: Mon, 14 Dec 2020 17:39:51 +0000 (-0500)
Subject: stapbpf (for PR27030): bugfix error messages in bpf assembly
X-Git-Tag: release-4.5~123
X-Git-Url: https://sourceware.org/git/?a=commitdiff_plain;h=b71d20af;p=systemtap.git

stapbpf (for PR27030): bugfix error messages in bpf assembly

Need to retain the asm_stmts vector so that bpf assembly tokens
are not deallocated on exception throw.

Otherwise, printing semantic errors from bpf assembly causes segfault.

* bpf-translate.cxx (struct bpf_unparser): retain asm_stmts vector.
(bpf_unparser::visit_embeddedcode): reuse retained asm_stmts vector.
---

diff --git a/bpf-translate.cxx b/bpf-translate.cxx
index f61a088a0..b463cc818 100644
--- a/bpf-translate.cxx
+++ b/bpf-translate.cxx
@@ -173,6 +173,7 @@ struct bpf_unparser : public throwing_visitor
 
   // Used to track errors.
   value *error_status;
+  std::vector<asm_stmt> asm_stmts;
 
   // Used to switch execution of program to catch blocks.
   std::vector<block *> catch_jump;
@@ -1477,7 +1478,9 @@ bpf_unparser::visit_embeddedcode (embeddedcode *s)
 #ifdef DEBUG_CODEGEN
   this_ins.notes.push("asm");
 #endif
-  std::vector<asm_stmt> statements;
+  // XXX retain asm_stmts to avoid deallocating tok on throw
+  std::vector<asm_stmt> &statements = this->asm_stmts;
+  statements.clear();
   asm_stmt stmt;
 
   // PR24528: The /* userspace */ annotation is used to mark