[binutils-gdb] gdb: care for dynamic objfiles in build_id_bfd_get ()

[Jan Vrany <jv@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=722e0dd9e4f03d66666c5b62e162da31cafe6d9f

commit 722e0dd9e4f03d66666c5b62e162da31cafe6d9f
Author: Jan Vrany <jan.vrany@labware.com>
Date:   Wed Jan 18 11:34:37 2023 +0000

    gdb: care for dynamic objfiles in build_id_bfd_get ()
    
    Accessing gdb.Objfile.build_id caused GDB to crash when objfile is
    dynamic, that is created by JIT reader API.
    
    The issue was NULL-pointer dereferencing in build_id_bfd_get () because
    dynamic objfiles have no underlaying BFD structure. This commit fixes
    the problem by a NULL-check in build_id_bfd_get ().

Diff:
---
 gdb/build-id.c                        | 6 ++++++
 gdb/testsuite/gdb.base/jit-reader.exp | 4 ++++
 2 files changed, 10 insertions(+)

diff --git a/gdb/build-id.c b/gdb/build-id.c
index c82f96402c8..801eb004ad7 100644
--- a/gdb/build-id.c
+++ b/gdb/build-id.c
@@ -32,6 +32,12 @@
 const struct bfd_build_id *
 build_id_bfd_get (bfd *abfd)
 {
+  /* Dynamic objfiles such as ones created by JIT reader API
+     have no underlaying bfd structure (that is, objfile->obfd
+     is NULL).  */
+  if (abfd == nullptr)
+    return nullptr;
+
   if (!bfd_check_format (abfd, bfd_object)
       && !bfd_check_format (abfd, bfd_core))
     return NULL;
diff --git a/gdb/testsuite/gdb.base/jit-reader.exp b/gdb/testsuite/gdb.base/jit-reader.exp
index fd0c5f56d6e..399cb67dcce 100644
--- a/gdb/testsuite/gdb.base/jit-reader.exp
+++ b/gdb/testsuite/gdb.base/jit-reader.exp
@@ -227,6 +227,10 @@ proc jit_reader_test {} {
 		gdb_test "python print(list(map(lambda objf : objf.filename, gdb.objfiles())))" \
 		    "$any'<< JIT compiled code at $hex >>'$any" \
 		    "python gdb.Objfile.filename"
+
+		gdb_test "python print( \[o for o in gdb.objfiles() if o.filename.startswith('<< JIT compiled code')\]\[0\].build_id )" \
+		    "None" \
+		    "python gdb.Objfile.build_id"
 	    }
 	}
     }