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| author | Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> | 2020-07-16 18:12:15 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-07-29 11:16:54 +0300 |
| commit | e1e622d0d979ac6da15ba929834263cd0190d0f3 (patch) | |
| tree | 7969e8a77041940a0849f14f7e1b20a856cda3b5 | |
| parent | 77c14a5e4db6d3b09ff665ebae85706317ff8af0 (diff) | |
| download | linux-e1e622d0d979ac6da15ba929834263cd0190d0f3.tar.xz | |
binder: Don't use mmput() from shrinker function.
commit f867c771f98891841c217fa8459244ed0dd28921 upstream.
syzbot is reporting that mmput() from shrinker function has a risk of
deadlock [1], for delayed_uprobe_add() from update_ref_ctr() calls
kzalloc(GFP_KERNEL) with delayed_uprobe_lock held, and
uprobe_clear_state() from __mmput() also holds delayed_uprobe_lock.
Commit a1b2289cef92ef0e ("android: binder: drop lru lock in isolate
callback") replaced mmput() with mmput_async() in order to avoid sleeping
with spinlock held. But this patch replaces mmput() with mmput_async() in
order not to start __mmput() from shrinker context.
[1] https://syzkaller.appspot.com/bug?id=bc9e7303f537c41b2b0cc2dfcea3fc42964c2d45
Reported-by: syzbot <syzbot+1068f09c44d151250c33@syzkaller.appspotmail.com>
Reported-by: syzbot <syzbot+e5344baa319c9a96edec@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Michal Hocko <mhocko@suse.com>
Acked-by: Todd Kjos <tkjos@google.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/4ba9adb2-43f5-2de0-22de-f6075c1fab50@i-love.sakura.ne.jp
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/android/binder_alloc.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c index 6e5e6fb7e4c9..3371b986e3b4 100644 --- a/drivers/android/binder_alloc.c +++ b/drivers/android/binder_alloc.c @@ -987,7 +987,7 @@ enum lru_status binder_alloc_free_page(struct list_head *item, trace_binder_unmap_user_end(alloc, index); } up_read(&mm->mmap_sem); - mmput(mm); + mmput_async(mm); trace_binder_unmap_kernel_start(alloc, index); |