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.

Cc: stable@vger.kernel.org Signed-off-by: Luís Henriques lhenriques@suse.de --- fs/ocfs2/super.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c index 0b0e6a132101..988d1c076861 100644 --- a/fs/ocfs2/super.c +++ b/fs/ocfs2/super.c @@ -952,8 +952,10 @@ static void ocfs2_disable_quotas(struct ocfs2_super *osb) 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