lkml.org 
[lkml]   [2019]   [Dec]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 3/3] init: use do_mount() instead of ksys_mount()
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

\
 
 \ /
  Last update: 2019-12-16 16:54    [W:0.052 / U:2.536 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site