linux-kernel - [PATCH 5.0 41/52] drm/vkms: Fix flush_work() without INIT

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Message-Id: <20190326042703.158950790@linuxfoundation.org>
Date:   Tue, 26 Mar 2019 15:30:28 +0900
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        Shayenne Moura <shayenneluzmoura@...il.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        syzbot <syzbot+12f1b031b6da017e34f8@...kaller.appspotmail.com>
Subject: [PATCH 5.0 41/52] drm/vkms: Fix flush_work() without INIT_WORK().

5.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>

commit b30b61ff6b1dc37f276cf56a8328b80086a3ffca upstream.

syzbot is hitting a lockdep warning [1] because flush_work() is called
without INIT_WORK() after kzalloc() at vkms_atomic_crtc_reset().

Commit 6c234fe37c57627a ("drm/vkms: Implement CRC debugfs API") added
INIT_WORK() to only vkms_atomic_crtc_duplicate_state() side. Assuming
that lifecycle of crc_work is appropriately managed, fix this problem
by adding INIT_WORK() to vkms_atomic_crtc_reset() side.

[1] https://syzkaller.appspot.com/bug?id=a5954455fcfa51c29ca2ab55b203076337e1c770

Reported-and-tested-by: syzbot <syzbot+12f1b031b6da017e34f8@...kaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Reviewed-by: Shayenne Moura <shayenneluzmoura@...il.com>
Signed-off-by: Daniel Vetter <daniel.vetter@...ll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/1547829823-9877-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/vkms/vkms_crtc.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/gpu/drm/vkms/vkms_crtc.c
+++ b/drivers/gpu/drm/vkms/vkms_crtc.c
@@ -98,6 +98,7 @@ static void vkms_atomic_crtc_reset(struc
 	vkms_state = kzalloc(sizeof(*vkms_state), GFP_KERNEL);
 	if (!vkms_state)
 		return;
+	INIT_WORK(&vkms_state->crc_work, vkms_crc_work_handle);
 
 	crtc->state = &vkms_state->base;
 	crtc->state->crtc = crtc;