[PATCH v2 0/2] Aarch64: Fix segfault when casting dummy calls

Alan Hayward
2018-10-01T15:53:08Z

This is a reworking of a patch I posted in March.
V1 had a long discussion which was then paused to wait for
Pedro's IFUNC rewrite.

Prevent the int cast in the following causing a segfault on aarch64:
(gdb) b foo if (int)strcmp(name,"abc") == 0
(gdb) run

This is because to aarch64_push_dummy_call determines the return type
of the function and then does not check for null pointer.

A null pointer for the return type means either 1) the call has a
cast or 2) an error has occured.
You can see this in infcall.c:call_function_by_hand_dummy():

CORE_ADDR funaddr = find_function_addr (function, &values_type, &ftype);

if (values_type == NULL)
values_type = default_return_type;
if (values_type == NULL)
{
const char *name = get_function_name (funaddr,
name_buf, sizeof (name_buf));
error (_("'%s' has unknown return type; "
"cast the call to its declared return type"),
name);
}

In aarch64_push_dummy_call we do not have default_return_type, so cannot
determine between the two cases.

(In addition, aarch64_push_dummy_call incorrectly resolves the return
type for IFUNC).

However, aarch64_push_dummy_call only requires the return value in order
to calculate lang_struct_return ... which has previously been calculated
in the caller:

This is slightly awkward, ideally the flag "lang_struct_return"
would be passed to the targets implementation of push_dummy_call.
Rather that change the target interface we call the language code
directly ourselves.

The fix is simple:
Patch 1: Update gdbarch interface to pass lang_struct_return.
Patch 2: Remove incorrect code and use the passed in lang_struct_return.

Built on x86 target all build and tested on aarch64.

Alan Hayward (2):
Add lang_struct_return to _push_dummy_call
Aarch64: Fix segfault when casting dummy calls

gdb/aarch64-tdep.c | 29 +-----
gdb/alpha-tdep.c | 3 +-
gdb/amd64-tdep.c | 3 +-
gdb/amd64-windows-tdep.c | 3 +-
gdb/arc-tdep.c | 2 +-
gdb/arm-tdep.c | 2 +-
gdb/avr-tdep.c | 3 +-
gdb/bfin-tdep.c | 1 +
gdb/cris-tdep.c | 3 +-
gdb/csky-tdep.c | 3 +-
gdb/frv-tdep.c | 3 +-
gdb/gdbarch.c | 4 +-
gdb/gdbarch.h | 4 +-
gdb/gdbarch.sh | 2 +-
gdb/h8300-tdep.c | 3 +-
gdb/hppa-tdep.c | 6 +-
gdb/i386-darwin-tdep.c | 3 +-
gdb/i386-tdep.c | 2 +-
gdb/ia64-tdep.c | 3 +-
gdb/infcall.c | 3 +-
gdb/iq2000-tdep.c | 3 +-
gdb/lm32-tdep.c | 3 +-
gdb/m32c-tdep.c | 2 +-
gdb/m32r-tdep.c | 2 +-
gdb/m68hc11-tdep.c | 3 +-
gdb/m68k-tdep.c | 2 +-
gdb/mep-tdep.c | 2 +-
gdb/mips-tdep.c | 15 +--
gdb/mn10300-tdep.c | 1 +
gdb/msp430-tdep.c | 3 +-
gdb/nds32-tdep.c | 3 +-
gdb/nios2-tdep.c | 3 +-
gdb/or1k-tdep.c | 3 +-
gdb/ppc-sysv-tdep.c | 6 +-
gdb/ppc-tdep.h | 2 +
gdb/riscv-tdep.c | 1 +
gdb/rl78-tdep.c | 3 +-
gdb/rs6000-aix-tdep.c | 3 +-
gdb/rs6000-lynx178-tdep.c | 3 +-
gdb/rx-tdep.c | 2 +-
gdb/s390-tdep.c | 3 +-
gdb/score-tdep.c | 3 +-
gdb/sh-tdep.c | 2 +
gdb/sparc-tdep.c | 3 +-
gdb/sparc64-tdep.c | 3 +-
gdb/spu-tdep.c | 3 +-
gdb/testsuite/gdb.base/condbreak-solib-lib.cc | 21 +++++
.../gdb.base/condbreak-solib-main.cc | 33 +++++++
gdb/testsuite/gdb.base/condbreak-solib.exp | 93 +++++++++++++++++++
gdb/tic6x-tdep.c | 3 +-
gdb/tilegx-tdep.c | 1 +
gdb/v850-tdep.c | 1 +
gdb/vax-tdep.c | 2 +-
gdb/xstormy16-tdep.c | 1 +
gdb/xtensa-tdep.c | 1 +
55 files changed, 246 insertions(+), 77 deletions(-)
create mode 100644 gdb/testsuite/gdb.base/condbreak-solib-lib.cc
create mode 100644 gdb/testsuite/gdb.base/condbreak-solib-main.cc
create mode 100644 gdb/testsuite/gdb.base/condbreak-solib.exp

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2.17.1 (Apple Git-112)