[PATCH] scripts: kconfig: fix deref after null in menu.c

[ant . v . moryakov]

From: Anton Moryakov <ant.v.morya...@gmail.com>

Static analyzer detected a potential NULL pointer dereference when 'sym'
pointer is passed to for_all_prompts() and other functions after being
checked for NULL earlier in the function.

The issue could occur when called from gstr get_relations_str() with
NULL symbol pointer.

Changes made:
1. Added early return if sym is NULL or has no name
2. Added NULL checks before all sym pointer dereferences
3. Maintained existing functionality for valid symbols

Signed-off-by: Anton Moryakov <ant.v.morya...@gmail.com>
---
 scripts/kconfig/menu.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
index 0fe7f3255af..2907f0ebfbf 100644
--- a/scripts/kconfig/menu.c
+++ b/scripts/kconfig/menu.c
@@ -796,6 +796,9 @@ static void get_symbol_str(struct gstr *r, struct symbol 
*sym,
 {
        struct property *prop;
 
+       if (!sym || !sym->name)
+               return;
+
        if (sym && sym->name) {
                str_printf(r, "Symbol: %s [=%s]\n", sym->name,
                           sym_get_string_value(sym));
@@ -809,7 +812,8 @@ static void get_symbol_str(struct gstr *r, struct symbol 
*sym,
                        }
                }
        }
-       for_all_prompts(sym, prop)
+       if(sym)
+               for_all_prompts(sym, prop)
                get_prompt_str(r, prop, head);
 
        prop = get_symbol_prop(sym);
@@ -823,14 +827,16 @@ static void get_symbol_str(struct gstr *r, struct symbol 
*sym,
                }
        }
 
-       get_symbol_props_str(r, sym, P_SELECT, "  Selects: ");
+       if(sym)
+               get_symbol_props_str(r, sym, P_SELECT, "  Selects: ");
        if (sym->rev_dep.expr) {
                expr_gstr_print_revdep(sym->rev_dep.expr, r, yes, "  Selected 
by [y]:\n");
                expr_gstr_print_revdep(sym->rev_dep.expr, r, mod, "  Selected 
by [m]:\n");
                expr_gstr_print_revdep(sym->rev_dep.expr, r, no, "  Selected by 
[n]:\n");
        }
 
-       get_symbol_props_str(r, sym, P_IMPLY, "  Implies: ");
+       if (sym)
+               get_symbol_props_str(r, sym, P_IMPLY, "  Implies: ");
        if (sym->implied.expr) {
                expr_gstr_print_revdep(sym->implied.expr, r, yes, "  Implied by 
[y]:\n");
                expr_gstr_print_revdep(sym->implied.expr, r, mod, "  Implied by 
[m]:\n");
-- 
2.30.2