From 230f6fa2c1db6a3f3e668cfe95995ac8e6eee212 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 9 Feb 2022 16:40:41 -0800 Subject: overflow: Provide constant expression struct_size There have been cases where struct_size() (or flex_array_size()) needs to be calculated for an initializer, which requires it be a constant expression. This is possible when the "count" argument is a constant expression, so provide this ability for the helpers. Cc: Gustavo A. R. Silva Cc: Nathan Chancellor Cc: Nick Desaulniers Cc: Rasmus Villemoes Signed-off-by: Kees Cook Reviewed-by: Gustavo A. R. Silva Tested-by: Gustavo A. R. Silva Link: https://lore.kernel.org/lkml/20220210010407.GA701603@embeddedor --- lib/test_overflow.c | 26 +++++++++++++++++--------- 1 file changed, 17 insertions(+), 9 deletions(-) (limited to 'lib/test_overflow.c') diff --git a/lib/test_overflow.c b/lib/test_overflow.c index 712fb2351c27..f6530fce799d 100644 --- a/lib/test_overflow.c +++ b/lib/test_overflow.c @@ -602,10 +602,18 @@ struct __test_flex_array { static int __init test_overflow_size_helpers(void) { + /* Make sure struct_size() can be used in a constant expression. */ + u8 ce_array[struct_size((struct __test_flex_array *)0, data, 55)]; struct __test_flex_array *obj; int count = 0; int err = 0; int var; + volatile int unconst = 0; + + /* Verify constant expression against runtime version. */ + var = 55; + OPTIMIZER_HIDE_VAR(var); + err |= sizeof(ce_array) != struct_size(obj, data, var); #define check_one_size_helper(expected, func, args...) ({ \ bool __failure = false; \ @@ -663,28 +671,28 @@ static int __init test_overflow_size_helpers(void) flex_array_size, obj, data, var++); err |= check_one_size_helper(5 * sizeof(*obj->data), flex_array_size, obj, data, var++); - err |= check_one_size_helper(0, flex_array_size, obj, data, 0); + err |= check_one_size_helper(0, flex_array_size, obj, data, 0 + unconst); err |= check_one_size_helper(sizeof(*obj->data), - flex_array_size, obj, data, 1); + flex_array_size, obj, data, 1 + unconst); err |= check_one_size_helper(7 * sizeof(*obj->data), - flex_array_size, obj, data, 7); + flex_array_size, obj, data, 7 + unconst); err |= check_one_size_helper(SIZE_MAX, - flex_array_size, obj, data, -1); + flex_array_size, obj, data, -1 + unconst); err |= check_one_size_helper(SIZE_MAX, - flex_array_size, obj, data, SIZE_MAX - 4); + flex_array_size, obj, data, SIZE_MAX - 4 + unconst); var = 4; err |= check_one_size_helper(sizeof(*obj) + (4 * sizeof(*obj->data)), struct_size, obj, data, var++); err |= check_one_size_helper(sizeof(*obj) + (5 * sizeof(*obj->data)), struct_size, obj, data, var++); - err |= check_one_size_helper(sizeof(*obj), struct_size, obj, data, 0); + err |= check_one_size_helper(sizeof(*obj), struct_size, obj, data, 0 + unconst); err |= check_one_size_helper(sizeof(*obj) + sizeof(*obj->data), - struct_size, obj, data, 1); + struct_size, obj, data, 1 + unconst); err |= check_one_size_helper(SIZE_MAX, - struct_size, obj, data, -3); + struct_size, obj, data, -3 + unconst); err |= check_one_size_helper(SIZE_MAX, - struct_size, obj, data, SIZE_MAX - 3); + struct_size, obj, data, SIZE_MAX - 3 + unconst); pr_info("%d overflow size helper tests finished\n", count); -- cgit