From: Minchan Kim <minchan@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
linux-api@vger.kernel.org, oleksandr@redhat.com,
Suren Baghdasaryan <surenb@google.com>,
Tim Murray <timmurray@google.com>,
Daniel Colascione <dancol@google.com>,
Sandeep Patil <sspatil@google.com>,
Sonny Rao <sonnyrao@google.com>,
Brian Geffon <bgeffon@google.com>, Michal Hocko <mhocko@suse.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Shakeel Butt <shakeelb@google.com>,
John Dias <joaodias@google.com>,
Joel Fernandes <joel@joelfernandes.org>,
Alexander Duyck <alexander.h.duyck@linux.intel.com>,
Minchan Kim <minchan@kernel.org>, Oleg Nesterov <oleg@redhat.com>
Subject: [PATCH v4 3/8] mm: validate mm in do_madvise
Date: Wed, 12 Feb 2020 15:39:41 -0800 [thread overview]
Message-ID: <20200212233946.246210-4-minchan@kernel.org> (raw)
In-Reply-To: <20200212233946.246210-1-minchan@kernel.org>
Oleg pointed out mm could be nulllified right after mm_access succeeds.
This patch validates it before the using.
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
mm/madvise.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/mm/madvise.c b/mm/madvise.c
index 8611f1d39289..bb04c7897eb9 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -1073,7 +1073,11 @@ int do_madvise(struct task_struct *task, unsigned long start,
int write;
size_t len;
struct blk_plug plug;
- struct mm_struct *mm = task->mm;
+ struct mm_struct *mm = READ_ONCE(task->mm);
+
+ /* task can exit and nullify its ->mm right after mm_access() */
+ if (!mm)
+ return -ESRCH;
start = untagged_addr(start);
--
2.25.0.225.g125e21ebc7-goog
next prev parent reply other threads:[~2020-02-12 23:40 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-12 23:39 [PATCH v4 0/8] introduce memory hinting API for external process Minchan Kim
2020-02-12 23:39 ` Minchan Kim
2020-02-12 23:39 ` [PATCH v4 1/8] mm: pass task to do_madvise Minchan Kim
2020-02-12 23:39 ` Minchan Kim
2020-02-13 0:21 ` Alexander Duyck
2020-02-13 0:21 ` Alexander Duyck
2020-02-13 0:21 ` Alexander Duyck
2020-02-13 17:02 ` Minchan Kim
2020-02-13 17:35 ` Jann Horn
2020-02-13 17:35 ` Jann Horn
2020-02-12 23:39 ` [PATCH v4 2/8] mm: introduce external memory hinting API Minchan Kim
2020-02-13 14:08 ` Jann Horn
2020-02-13 14:08 ` Jann Horn
2020-02-13 16:10 ` Minchan Kim
2020-02-12 23:39 ` Minchan Kim [this message]
2020-02-12 23:39 ` [PATCH v4 4/8] mm: check fatal signal pending of target process Minchan Kim
2020-02-12 23:39 ` Minchan Kim
2020-02-12 23:39 ` [PATCH v4 5/8] mm/madvise: employ mmget_still_valid for write lock Minchan Kim
2020-02-12 23:39 ` [PATCH v4 6/8] mm/madvise: allow KSM hints for remote API Minchan Kim
2020-02-12 23:39 ` [PATCH v4 7/8] pid: export pidfd_get_pid Minchan Kim
2020-02-12 23:39 ` Minchan Kim
2020-02-13 0:25 ` Alexander Duyck
2020-02-13 0:25 ` Alexander Duyck
2020-02-13 0:25 ` Alexander Duyck
2020-02-13 17:08 ` Minchan Kim
2020-02-12 23:39 ` [PATCH v4 8/8] mm: support both pid and pidfd for process_madvise Minchan Kim
2020-02-13 0:28 ` Alexander Duyck
2020-02-13 0:28 ` Alexander Duyck
2020-02-13 0:28 ` Alexander Duyck
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