[Ocfs2-devel] + ocfs2-fix-use-after-free-when-unmounting-read-only-filesystem.patch added to mm-hotfixes-unstable branch

[Joseph Qi]

Hi Andrew,

There is an updated version v2, which describe more clearly about the
case:
https://lore.kernel.org/ocfs2-devel/e9fc4b2f-1fcc-7c31-f346-59eccff50f9b@linux.alibaba.com/T/#u

Thanks,
Joseph

On 5/26/23 4:55 AM, Andrew Morton wrote:
> The patch titled
>      Subject: ocfs2: fix use-after-free when unmounting read-only filesystem
> has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
>      ocfs2-fix-use-after-free-when-unmounting-read-only-filesystem.patch
> 
> This patch will shortly appear at
>      https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/ocfs2-fix-use-after-free-when-unmounting-read-only-filesystem.patch
> 
> This patch will later appear in the mm-hotfixes-unstable branch at
>     git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
> 
> Before you just go and hit "reply", please:
>    a) Consider who else should be cc'ed
>    b) Prefer to cc a suitable mailing list as well
>    c) Ideally: find the original patch on the mailing list and do a
>       reply-to-all to that, adding suitable additional cc's
> 
> *** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
> 
> The -mm tree is included into linux-next via the mm-everything
> branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
> and is updated there every 2-3 working days
> 
> ------------------------------------------------------
> From: Luís Henriques <ocfs2-devel at oss.oracle.com>
> Subject: ocfs2: fix use-after-free when unmounting read-only filesystem
> Date: Mon, 22 May 2023 11:21:12 +0100
> 
> It's trivial to trigger a use-after-free bug in the ocfs2 quotas code
> using fstest generic/452.  After mounting a filesystem as read-only,
> quotas are suspended and ocfs2_mem_dqinfo is freed through
> ->ocfs2_local_free_info().  When unmounting the filesystem, an UAF access
> to the oinfo will eventually cause a crash.
> 
> Link: https://lkml.kernel.org/r/20230522102112.9031-1-lhenriques@suse.de
> Signed-off-by: Luís Henriques <lhenriques at suse.de>
> Reviewed-by: Joseph Qi <joseph.qi at linux.alibaba.com>
> Tested-by: Joseph Qi <joseph.qi at linux.alibaba.com>
> Cc: Mark Fasheh <mark at fasheh.com>
> Cc: Joel Becker <jlbec at evilplan.org>
> Cc: Junxiao Bi <junxiao.bi at oracle.com>
> Cc: Changwei Ge <gechangwei at live.cn>
> Cc: Gang He <ghe at suse.com>
> Cc: Jun Piao <piaojun at huawei.com>
> Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
> ---
> 
>  fs/ocfs2/super.c |    6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> --- a/fs/ocfs2/super.c~ocfs2-fix-use-after-free-when-unmounting-read-only-filesystem
> +++ a/fs/ocfs2/super.c
> @@ -952,8 +952,10 @@ static void ocfs2_disable_quotas(struct
>  	for (type = 0; type < OCFS2_MAXQUOTAS; type++) {
>  		if (!sb_has_quota_loaded(sb, type))
>  			continue;
> -		oinfo = sb_dqinfo(sb, type)->dqi_priv;
> -		cancel_delayed_work_sync(&oinfo->dqi_sync_work);
> +		if (!sb_has_quota_suspended(sb, type)) {
> +			oinfo = sb_dqinfo(sb, type)->dqi_priv;
> +			cancel_delayed_work_sync(&oinfo->dqi_sync_work);
> +		}
>  		inode = igrab(sb->s_dquot.files[type]);
>  		/* Turn off quotas. This will remove all dquot structures from
>  		 * memory and so they will be automatically synced to global
> _
> 
> Patches currently in -mm which might be from ocfs2-devel at oss.oracle.com are
> 
> ocfs2-fix-use-after-free-when-unmounting-read-only-filesystem.patch