[PATCH PR gdb/22736] [aarch64] gdb crashes on a conditional breakpoint with cast return type

Alan Hayward
2018-03-01T17:03:52Z

On aarch64, the (int) casting in the following causes a gdb segfault:
$ ./gdb ./gdb
(gdb) b dwarf2_physname if (int)strcmp (name, "another_thread_local") == 0
(gdb) run a.out // use any a.out

This is due to getting a null pointer from TYPE_TARGET_TYPE, and then
using it for language_pass_by_reference().

Fixed by adding a null check, similar to other occurrences in gdb.

Tested on aarch64 with make check using unix, native_gdbserver.

Alan.

2018-03-01 Alan Hayward <alan.hayward@arm.com>

* aarch64-tdep.c (aarch64_push_dummy_call): Check for null
return_type.

diff --git a/gdb/aarch64-tdep.c b/gdb/aarch64-tdep.c
index f08945ea07101e1cd7906ca640c023ac7d189dd9..ef982c78fe64ceef3c7c378fd22d76604bf81c31 100644
--- a/gdb/aarch64-tdep.c
+++ b/gdb/aarch64-tdep.c
@@ -1382,7 +1382,7 @@ aarch64_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
struct aarch64_call_info info;
struct type *func_type;
struct type *return_type;
- int lang_struct_return;
+ int lang_struct_return = 0;

memset (&info, 0, sizeof (info));

@@ -1424,7 +1424,8 @@ aarch64_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
given an additional initial argument, a hidden pointer to the
return slot in memory. */
return_type = TYPE_TARGET_TYPE (func_type);
- lang_struct_return = language_pass_by_reference (return_type);
+ if (return_type != nullptr)
+ lang_struct_return = language_pass_by_reference (return_type);

/* Set the return address. For the AArch64, the return breakpoint
is always at BP_ADDR. */