From 6aaa31aeb9cf260e1b7155cc11ec864f052db5ec Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Thu, 25 Feb 2021 17:22:42 -0800 Subject: ubsan: remove overflow checks Since GCC 8.0 -fsanitize=signed-integer-overflow doesn't work with -fwrapv. -fwrapv makes signed overflows defines and GCC essentially disables ubsan checks. On GCC < 8.0 -fwrapv doesn't have influence on -fsanitize=signed-integer-overflow setting, so it kinda works but generates false-positves and violates uaccess rules: lib/iov_iter.o: warning: objtool: iovec_from_user()+0x22d: call to __ubsan_handle_add_overflow() with UACCESS enabled Disable signed overflow checks to avoid these problems. Remove unsigned overflow checks as well. Unsigned overflow appeared as side effect of commit cdf8a76fda4a ("ubsan: move cc-option tests into Kconfig"), but it never worked (kernel doesn't boot). And unsigned overflows are allowed by C standard, so it just pointless. Link: https://lkml.kernel.org/r/20210209232348.20510-1-ryabinin.a.a@gmail.com Signed-off-by: Andrey Ryabinin Acked-by: Peter Zijlstra (Intel) Cc: Josh Poimboeuf Cc: Randy Dunlap Cc: Stephen Rothwell Cc: Dmitry Vyukov Cc: Kees Cook Cc: Alexander Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/ubsan.c | 68 ------------------------------------------------------------- 1 file changed, 68 deletions(-) (limited to 'lib/ubsan.c') diff --git a/lib/ubsan.c b/lib/ubsan.c index bec38c64d6a6..26229973049d 100644 --- a/lib/ubsan.c +++ b/lib/ubsan.c @@ -163,74 +163,6 @@ static void ubsan_epilogue(void) } } -static void handle_overflow(struct overflow_data *data, void *lhs, - void *rhs, char op) -{ - - struct type_descriptor *type = data->type; - char lhs_val_str[VALUE_LENGTH]; - char rhs_val_str[VALUE_LENGTH]; - - if (suppress_report(&data->location)) - return; - - ubsan_prologue(&data->location, type_is_signed(type) ? - "signed-integer-overflow" : - "unsigned-integer-overflow"); - - val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs); - val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs); - pr_err("%s %c %s cannot be represented in type %s\n", - lhs_val_str, - op, - rhs_val_str, - type->type_name); - - ubsan_epilogue(); -} - -void __ubsan_handle_add_overflow(void *data, - void *lhs, void *rhs) -{ - - handle_overflow(data, lhs, rhs, '+'); -} -EXPORT_SYMBOL(__ubsan_handle_add_overflow); - -void __ubsan_handle_sub_overflow(void *data, - void *lhs, void *rhs) -{ - handle_overflow(data, lhs, rhs, '-'); -} -EXPORT_SYMBOL(__ubsan_handle_sub_overflow); - -void __ubsan_handle_mul_overflow(void *data, - void *lhs, void *rhs) -{ - handle_overflow(data, lhs, rhs, '*'); -} -EXPORT_SYMBOL(__ubsan_handle_mul_overflow); - -void __ubsan_handle_negate_overflow(void *_data, void *old_val) -{ - struct overflow_data *data = _data; - char old_val_str[VALUE_LENGTH]; - - if (suppress_report(&data->location)) - return; - - ubsan_prologue(&data->location, "negation-overflow"); - - val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val); - - pr_err("negation of %s cannot be represented in type %s:\n", - old_val_str, data->type->type_name); - - ubsan_epilogue(); -} -EXPORT_SYMBOL(__ubsan_handle_negate_overflow); - - void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs) { struct overflow_data *data = _data; -- cgit