6.6-stable review patch. If anyone has any objections, please let me know.
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From: Kees Cook keescook@chromium.org
[ Upstream commit 1ee60356c2dca938362528404af95b8ef3e49b6a ]
The randstruct GCC plugin tried to discover "fake" flexible arrays to issue warnings about them in randomized structs. In the future LSM overhead reduction series, it would be legal to have a randomized struct with a 1-element array, and this should _not_ be treated as a flexible array, especially since commit df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3"). Disable the 0-sized and 1-element array discovery logic in the plugin, but keep the "true" flexible array check.
Cc: KP Singh kpsingh@kernel.org Cc: linux-hardening@vger.kernel.org Reported-by: kernel test robot lkp@intel.com Closes: https://lore.kernel.org/oe-kbuild-all/202311021532.iBwuZUZ0-lkp@intel.com/ Fixes: df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3") Reviewed-by: Bill Wendling morbo@google.com Acked-by: "Gustavo A. R. Silva" gustavoars@kernel.org Link: https://lore.kernel.org/r/20231104204334.work.160-kees@kernel.org Signed-off-by: Kees Cook keescook@chromium.org Signed-off-by: Sasha Levin sashal@kernel.org --- scripts/gcc-plugins/randomize_layout_plugin.c | 10 ---------- 1 file changed, 10 deletions(-)
diff --git a/scripts/gcc-plugins/randomize_layout_plugin.c b/scripts/gcc-plugins/randomize_layout_plugin.c index 951b74ba1b242..5e5744b65f8a9 100644 --- a/scripts/gcc-plugins/randomize_layout_plugin.c +++ b/scripts/gcc-plugins/randomize_layout_plugin.c @@ -273,8 +273,6 @@ static bool is_flexible_array(const_tree field) { const_tree fieldtype; const_tree typesize; - const_tree elemtype; - const_tree elemsize;
fieldtype = TREE_TYPE(field); typesize = TYPE_SIZE(fieldtype); @@ -282,20 +280,12 @@ static bool is_flexible_array(const_tree field) if (TREE_CODE(fieldtype) != ARRAY_TYPE) return false;
- elemtype = TREE_TYPE(fieldtype); - elemsize = TYPE_SIZE(elemtype); - /* size of type is represented in bits */
if (typesize == NULL_TREE && TYPE_DOMAIN(fieldtype) != NULL_TREE && TYPE_MAX_VALUE(TYPE_DOMAIN(fieldtype)) == NULL_TREE) return true;
- if (typesize != NULL_TREE && - (TREE_CONSTANT(typesize) && (!tree_to_uhwi(typesize) || - tree_to_uhwi(typesize) == tree_to_uhwi(elemsize)))) - return true; - return false; }