Messages in this thread | | | Date | Mon, 4 Jan 2021 16:13:17 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH] mm/uaccess: Use 'unsigned long' to placate UBSAN warnings, again |
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On Tue, Dec 22, 2020 at 11:04:54PM -0600, Josh Poimboeuf wrote: > GCC 7 has a known bug where UBSAN ignores '-fwrapv' and generates false > signed-overflow-UB warnings. The type mismatch between 'i' and > 'nr_segs' in copy_compat_iovec_from_user() is causing such a warning, > which also happens to violate uaccess rules: > > lib/iov_iter.o: warning: objtool: iovec_from_user()+0x22d: call to __ubsan_handle_add_overflow() with UACCESS enabled > > Fix it by making the variable types match. > > This is similar to a previous commit: > > 29da93fea3ea ("mm/uaccess: Use 'unsigned long' to placate UBSAN warnings on older GCC versions")
Maybe it's time we make UBSAN builds depend on GCC-8+ ?
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