linux-ext4 - Re: [PATCH] ext2/super: Fix a possible sleep-in-atomic bug in parse

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CA+55aFw9UB1ZKMk-JgLm=xBRST-9JaWv4unFtE3fsygjeVxEjg@mail.gmail.com>
Date:   Fri, 6 Oct 2017 18:37:11 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Jia-Ju Bai <baijiaju1990@....com>
Cc:     Al Viro <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.com>,
        Sagi Grimberg <sagi@...mberg.me>, james.smart@...adcom.com,
        "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ext2/super: Fix a possible sleep-in-atomic bug in parse_options

On Fri, Oct 6, 2017 at 6:20 PM, Jia-Ju Bai <baijiaju1990@....com> wrote:
>
> To fix it, GFP_KERNEL is replaced with GFP_ATOMIC.
> This bug is found by my static analysis tool and my code review.

I'm not saying your patch is wrong, but it's a shame that we do that
extra allocation in match_number() and match_u64int(), and that we
don't have anything that is just size-limited.

And there really isn't anything saying that we shouldn't do the same
silly thing to match_u64int(). Maybe we don't have any actual users
that need it for now, but still..

Oh well.

I do wonder if we shouldn't just use something like

 "skip leading zeroes, copy to size-limited stack location instead"

because the input length really *is* limited once you skip leading
zeroes (and whatever base marker we have). We might have at most a
64-bit value in octal, so 22 bytes max.

But I guess just changing the two GFP_KERNEL's to GFP_ATOMIC is much simpler.

               Linus