menuconfig: fix NULL pointer dereference when searching a symbol

Searching for PPC_EFIKA results in a segmentation fault, and it's
because get_symbol_prop() returns NULL.

In this case CONFIG_PPC_EFIKA is defined in arch/powerpc/platforms/
52xx/Kconfig, so it won't be parsed if ARCH!=PPC, but menuconfig knows
this symbol when it parses sound/soc/fsl/Kconfig:

    config SND_MPC52xx_SOC_EFIKA
        tristate "SoC AC97 Audio support for bbplan Efika and STAC9766"
        depends on PPC_EFIKA

This bug was introduced by commit bcdedcc1afd6 ("menuconfig: print more
info for symbol without prompts").

Reported-and-tested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Li Zefan <lizefan@huawei.com>
Tested-by: Libo Chen <libo.chen@huawei.com>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Michal Marek <mmarek@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
index 826da66..b5c7d90 100644 (file)
--- a/scripts/kconfig/menu.c
+++ b/scripts/kconfig/menu.c
@@ -600,14 +600,18 @@ void get_symbol_str(struct gstr *r, struct symbol *sym,
        }
        for_all_prompts(sym, prop)
                get_prompt_str(r, prop, head);
+
        prop = get_symbol_prop(sym);
-       str_printf(r, _("  Defined at %s:%d\n"), prop->menu->file->name,
-               prop->menu->lineno);
-       if (!expr_is_yes(prop->visible.expr)) {
-               str_append(r, _("  Depends on: "));
-               expr_gstr_print(prop->visible.expr, r);
-               str_append(r, "\n");
+       if (prop) {
+               str_printf(r, _("  Defined at %s:%d\n"), prop->menu->file->name,
+                       prop->menu->lineno);
+               if (!expr_is_yes(prop->visible.expr)) {
+                       str_append(r, _("  Depends on: "));
+                       expr_gstr_print(prop->visible.expr, r);
+                       str_append(r, "\n");
+               }
        }
+
        hit = false;
        for_all_properties(sym, prop, P_SELECT) {
                if (!hit) {