From: "Guido Günther" <agx@sigxcpu.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J . Wysocki" <rafael@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/3] init: use do_mount() instead of ksys_mount()
Date: Mon, 16 Dec 2019 16:53:32 +0100 [thread overview]
Message-ID: <20191216155332.GA29065@bogon.m.sigxcpu.org> (raw)
In-Reply-To: <CAHk-=wh8VLe3AEKhz=1bzSO=1fv4EM71EhufxuC=Gp=+bLhXoA@mail.gmail.com>
Hi,
On Sun, Dec 15, 2019 at 07:50:23PM -0800, Linus Torvalds wrote:
> On Sun, Dec 15, 2019 at 5:35 PM Ondřej Jirman <megi@xff.cz> wrote:
> >
> > Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
>
> Duh. So much for the trivial obvious conversion.
>
> It didn't take "data might be NULL" into account.
>
> A patch like this, perhaps? Untested..
>
> Linus
> init/do_mounts.c | 23 +++++++++++++----------
> 1 file changed, 13 insertions(+), 10 deletions(-)
>
> diff --git a/init/do_mounts.c b/init/do_mounts.c
> index f55cbd9cb818..d204f605dbce 100644
> --- a/init/do_mounts.c
> +++ b/init/do_mounts.c
> @@ -391,17 +391,19 @@ static int __init do_mount_root(const char *name, const char *fs,
> const int flags, const void *data)
> {
> struct super_block *s;
> - char *data_page;
> - struct page *p;
> + struct page *p = NULL;
> + char *data_page = NULL;
n> int ret;
>
> - /* do_mount() requires a full page as fifth argument */
> - p = alloc_page(GFP_KERNEL);
> - if (!p)
> - return -ENOMEM;
> -
> - data_page = page_address(p);
> - strncpy(data_page, data, PAGE_SIZE - 1);
> + if (data) {
> + /* do_mount() requires a full page as fifth argument */
> + p = alloc_page(GFP_KERNEL);
> + if (!p)
> + return -ENOMEM;
> + data_page = page_address(p);
> + strncpy(data_page, data, PAGE_SIZE - 1);
> + data_page[PAGE_SIZE - 1] = '\0';
> + }
>
> ret = do_mount(name, "/root", fs, flags, data_page);
> if (ret)
> @@ -417,7 +419,8 @@ static int __init do_mount_root(const char *name, const char *fs,
> MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
>
> out:
> - put_page(p);
> + if (p)
> + put_page(p);
> return ret;
> }
>
This unbroke tftpboot on arm64 on next-20191216 for me as well:
Tested-by: Guido Günther <agx@sigxcpu.org>
Cheers,
-- Guido
next prev parent reply other threads:[~2019-12-16 15:53 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-12 13:57 [PATCH 0/3] use do_mount() instead of ksys_mount() Dominik Brodowski
2019-12-12 13:57 ` [PATCH 1/3] devtmpfs: " Dominik Brodowski
2019-12-12 13:57 ` [PATCH 2/3] initrd: " Dominik Brodowski
2019-12-12 13:57 ` [PATCH 3/3] init: " Dominik Brodowski
2019-12-16 1:35 ` Ondřej Jirman
2019-12-16 1:36 ` Ondřej Jirman
2019-12-16 3:50 ` Linus Torvalds
2019-12-16 5:13 ` Eric Biggers
2019-12-16 13:21 ` Geert Uytterhoeven
2019-12-16 15:04 ` Guenter Roeck
2019-12-16 15:53 ` Guido Günther [this message]
2019-12-16 21:12 ` Nick Desaulniers
2019-12-17 6:38 ` Dominik Brodowski
2019-12-17 18:04 ` Nick Desaulniers
2019-12-12 17:11 ` [PATCH 0/3] " Linus Torvalds
2019-12-12 18:37 ` Al Viro
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191216155332.GA29065@bogon.m.sigxcpu.org \
--to=agx@sigxcpu.org \
--cc=akpm@linux-foundation.org \
--cc=gregkh@linuxfoundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@dominikbrodowski.net \
--cc=mingo@kernel.org \
--cc=rafael@kernel.org \
--cc=torvalds@linux-foundation.org \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).