Messages in this thread | | | Subject | Re: [PATCH] mm/uaccess: Use 'unsigned long' to placate UBSAN warnings, again | From | Randy Dunlap <> | Date | Tue, 22 Dec 2020 23:18:56 -0800 |
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On 12/22/20 9:04 PM, 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") > > Reported-by: Randy Dunlap <rdunlap@infradead.org> > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
All good. Thanks.
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
> --- > lib/iov_iter.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/lib/iov_iter.c b/lib/iov_iter.c > index 1635111c5bd2..2e6a42f5d1df 100644 > --- a/lib/iov_iter.c > +++ b/lib/iov_iter.c > @@ -1656,7 +1656,8 @@ static int copy_compat_iovec_from_user(struct iovec *iov, > { > const struct compat_iovec __user *uiov = > (const struct compat_iovec __user *)uvec; > - int ret = -EFAULT, i; > + int ret = -EFAULT; > + unsigned long i; > > if (!user_access_begin(uvec, nr_segs * sizeof(*uvec))) > return -EFAULT; >
-- ~Randy
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