With a simple test-case:
...
$ cat test.c
char *p = "a";
int main (void) {
return strlen (p);
}
$ gcc -g test.c
...
we run into this segfault:
...
$ gdb -q -batch a.out -ex start -ex "p strlen (p)"
Temporary breakpoint 1 at 0x1151: file test.c, line 4.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Temporary breakpoint 1, main () at test.c:4
4 return strlen (p);
Fatal signal: Segmentation fault
...
The strlen is an ifunc, and consequently during the call to
call_function_by_hand_dummy for "p strlen (p)" another call
to call_function_by_hand_dummy is used to resolve the ifunc.
This invalidates the get_current_frame () result in the outer call.
Fix this by using prepare_reinflate and reinflate.
Note that this series (
https://inbox.sourceware.org/gdb-patches/
20221214033441.499512-1-simon.marchi@polymtl.ca/ )
should address this problem, but this patch is a simpler fix which is easy to
backport.
Tested on x86_64-linux.
Co-Authored-By: Tom de Vries <tdevries@suse.de>
PR gdb/29941
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29941
bool stack_temporaries = thread_stack_temporaries_enabled_p (call_thread.get ());
frame = get_current_frame ();
+ frame.prepare_reinflate ();
gdbarch = get_frame_arch (frame);
if (!gdbarch_push_dummy_call_p (gdbarch))
"target calling convention."),
get_function_name (funaddr, name_buf, sizeof (name_buf)));
+ frame.reinflate ();
+
if (values_type == NULL || values_type->is_stub ())
values_type = default_return_type;
if (values_type == NULL)
# Test GDB will automatically indirect the call.
if {!$resolver_debug && !$final_debug} {
+ # Do the test that is supposed to succeed first, to make sure
+ # elf_gnu_ifunc_record_cache is empty. This excercises PR28224.
+ gdb_test "p (int) gnu_ifunc (3)" " = 4"
+
gdb_test "p gnu_ifunc()" \
"'${dot}final' has unknown return type; cast the call to its declared return type"
gdb_test "p gnu_ifunc (3)" \
"'${dot}final' has unknown return type; cast the call to its declared return type"
- gdb_test "p (int) gnu_ifunc (3)" " = 4"
} else {
- gdb_test "p gnu_ifunc()" "Too few arguments in function call\\."
+ # Do the test that is supposed to succeed first, see above.
gdb_test "p gnu_ifunc (3)" " = 4"
+
+ gdb_test "p gnu_ifunc()" "Too few arguments in function call\\."
}
# Test that the resolver received its argument.