From: Kees Cook <keescook@chromium.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Josef Bacik <josef@toxicpanda.com>, Jens Axboe <axboe@kernel.dk>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Nick Desaulniers <ndesaulniers@google.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Sasha Levin <sashal@kernel.org>,
llvm@lists.linux.dev, stable <stable@vger.kernel.org>,
Arnd Bergmann <arnd@kernel.org>,
Naresh Kamboju <naresh.kamboju@linaro.org>,
Nathan Chancellor <nathan@kernel.org>,
Stephen Rothwell <sfr@canb.auug.org.au>,
Pavel Machek <pavel@ucw.cz>
Subject: Re: [PATCH 5.10] overflow.h: use new generic division helpers to avoid / operator
Date: Tue, 14 Sep 2021 11:47:58 -0700 [thread overview]
Message-ID: <202109141144.1AE2DDB@keescook> (raw)
In-Reply-To: <CAHk-=whiQBofgis_rkniz8GBP9wZtSZdcDEffgSLO62BUGV3gg@mail.gmail.com>
On Tue, Sep 14, 2021 at 11:30:03AM -0700, Linus Torvalds wrote:
> case NBD_SET_SIZE_BLOCKS:
> - if (check_mul_overflow((loff_t)arg, config->blksize, &bytesize))
> + bytesize = arg << config->blksize_bits;
> + if (bytesize >> config->blksize_bits != arg)
> return -EINVAL;
FWIW, it's probably better to avoid open-coding the check. There are
helpers for shift-left too. :)
+ if (check_shl_overflow(arg, config->blksize_bits, &bytesize))
--
Kees Cook
next prev parent reply other threads:[~2021-09-14 18:48 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-13 20:32 [PATCH 5.10] overflow.h: use new generic division helpers to avoid / operator Nick Desaulniers
2021-09-13 21:05 ` Rasmus Villemoes
2021-09-14 0:23 ` [PATCH v2] " Nick Desaulniers
2021-09-14 17:22 ` Greg Kroah-Hartman
2021-09-14 18:07 ` Nick Desaulniers
2021-09-14 18:12 ` Greg Kroah-Hartman
2021-09-14 17:32 ` [PATCH 5.10] " Kees Cook
2021-09-14 18:14 ` Linus Torvalds
2021-09-14 18:30 ` Linus Torvalds
2021-09-14 18:44 ` Nick Desaulniers
2021-09-14 18:48 ` Linus Torvalds
2021-09-14 18:56 ` Linus Torvalds
2021-09-14 19:10 ` Nick Desaulniers
2021-09-14 19:45 ` Linus Torvalds
2021-09-14 19:50 ` Nick Desaulniers
2021-09-14 19:57 ` Linus Torvalds
2021-09-14 18:47 ` Kees Cook [this message]
2021-09-14 18:54 ` Linus Torvalds
2021-09-14 19:12 ` Nick Desaulniers
2021-09-14 19:52 ` Linus Torvalds
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