From: Linus Torvalds <torvalds@linux-foundation.org>
To: Aleksa Sarai <cyphar@cyphar.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Christian Brauner <christian@brauner.io>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Al Viro <viro@zeniv.linux.org.uk>,
GNU C Library <libc-alpha@sourceware.org>,
Linux API <linux-api@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1 1/4] lib: introduce copy_struct_from_user() helper
Date: Wed, 25 Sep 2019 10:10:37 -0700 [thread overview]
Message-ID: <CAHk-=wjFeNjhtUxQ8npmXORz5RLQU7B_3wD=45eug1+MXnuYvA@mail.gmail.com> (raw)
In-Reply-To: <20190925165915.8135-2-cyphar@cyphar.com>
On Wed, Sep 25, 2019 at 10:00 AM Aleksa Sarai <cyphar@cyphar.com> wrote:
>
> +int is_zeroed_user(const void __user *from, size_t size)
I like how you've done this, but it's buggy and only works on 64-bit.
All the "u64" and "8" cases need to be "unsigned long" and
"sizeof(unsigned long)".
Part of that requirement is:
> + unsafe_get_user(val, (u64 __user *) from, err_fault);
This part works fine - although 64-bit accesses migth be much more
expensive and the win of unrolling might not be sufficient - but:
> + if (align) {
> + /* @from is unaligned. */
> + val &= ~aligned_byte_mask(align);
> + align = 0;
> + }
This part fundamentally only works on 'unsigned long'.
Linus
next prev parent reply other threads:[~2019-09-25 17:11 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-25 16:59 [PATCH v1 0/4] lib: introduce copy_struct_from_user() helper Aleksa Sarai
2019-09-25 16:59 ` [PATCH v1 1/4] " Aleksa Sarai
2019-09-25 17:10 ` Linus Torvalds [this message]
2019-09-25 17:20 ` Aleksa Sarai
2019-09-25 17:48 ` Linus Torvalds
2019-09-25 18:04 ` Al Viro
2019-09-25 18:13 ` Linus Torvalds
2019-09-25 19:43 ` Al Viro
2019-09-25 20:23 ` Linus Torvalds
2019-09-25 17:18 ` Christian Brauner
2019-09-25 17:20 ` Christian Brauner
2019-09-25 19:16 ` kbuild test robot
2019-09-25 20:47 ` kbuild test robot
2019-09-25 16:59 ` [PATCH v1 2/4] clone3: switch to copy_struct_from_user() Aleksa Sarai
2019-09-25 17:22 ` Christian Brauner
2019-09-25 18:59 ` kbuild test robot
2019-09-25 19:08 ` kbuild test robot
2019-09-25 16:59 ` [PATCH v1 3/4] sched_setattr: " Aleksa Sarai
2019-09-25 16:59 ` [PATCH v1 4/4] perf_event_open: " Aleksa Sarai
2019-09-25 17:09 ` [PATCH v1 0/4] lib: introduce copy_struct_from_user() helper Christian Brauner
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