Avoid buffer overflow in value_x_unop
authorTom Tromey <tom@tromey.com>
Wed, 28 Nov 2018 17:34:15 +0000 (10:34 -0700)
committerTom Tromey <tom@tromey.com>
Thu, 29 Nov 2018 17:49:38 +0000 (10:49 -0700)
commit3d5500e9580ec0f3cffeb1f1373834cbc1d2101d
tree2837b482e2aa5d2460995233132b01a3b4b85ff8
parentd105de22fc385da878e8db44c9503a7f30419322
Avoid buffer overflow in value_x_unop

Commit 6b1747cd1 ("invoke_xmethod & array_view") contains this change:

-  argvec = (struct value **) alloca (sizeof (struct value *) * 4);
+  value *argvec_storage[3];
+  gdb::array_view<value *> argvec = argvec_storage;

However, value_x_unop still does:

      argvec[2] = value_from_longest (builtin_type (gdbarch)->builtin_int, 0);
      argvec[3] = 0;

This triggers an error with -fsanitize=address from userdef.exp:

ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffdcf185068 at pc 0x000000e4f912 bp 0x7ffdcf184d80 sp 0x7ffdcf184d70
WRITE of size 8 at 0x7ffdcf185068 thread T0
    #0 0xe4f911 in value_x_unop(value*, exp_opcode, noside) ../../binutils-gdb/gdb/valarith.c:557
[...]

I think the two assignments to argvec[3] should just be removed, and
that this was intended in the earlier patch but just missed.

This passes userdef.exp with -fsanitize=address.

gdb/ChangeLog
2018-11-29  Tom Tromey  <tom@tromey.com>

* valarith.c (value_x_unop): Don't set argvec[3].
gdb/ChangeLog
gdb/valarith.c