linux-kernel - [PATCH] kconfig: check for a NULL pointer before access

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Message-ID: <CAGG=3QU5Yi2AfHS_poi8SgmatedRg-X8Ct74FOCJUc9iJNPnhg@mail.gmail.com>
Date: Thu, 22 May 2025 17:07:30 -0700
From: Bill Wendling <morbo@...gle.com>
To: Masahiro Yamada <masahiroy@...nel.org>, 
	Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] kconfig: check for a NULL pointer before access

The call to 'prop_get_symbol' may return NULL in some cases. The if-then
statement accesses the returned value without checking if it's
non-NULL. After inlining, the compiler may treat the conditional as
'undefined behavior', which the compiler may take the opportunity to do
whatever it wants with the UB path. This patch simply adds a check to
ensure that 'def_sym' is non-NULL to avoid this behavior.

Signed-off-by: Bill Wendling <morbo@...gle.com>
---
Cc: Masahiro Yamada <masahiroy@...nel.org>
Cc: linux-kbuild@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
---
 scripts/kconfig/symbol.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/kconfig/symbol.c b/scripts/kconfig/symbol.c
index d57f8cbba291..9c5068225328 100644
--- a/scripts/kconfig/symbol.c
+++ b/scripts/kconfig/symbol.c
@@ -272,7 +272,7 @@ struct symbol *sym_choice_default(struct menu *choice)
  if (prop->visible.tri == no)
  continue;
  def_sym = prop_get_symbol(prop);
- if (def_sym->visible != no)
+ if (def_sym && def_sym->visible != no)
  return def_sym;
  }

-- 
2.49.0.1164.gab81da1b16-goog