linux-kernel - [PATCH AUTOSEL 5.0 220/262] drm/vkms: Fix flush_work() without INIT

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Date:   Wed, 27 Mar 2019 14:01:15 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Sasha Levin <sashal@...nel.org>,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 5.0 220/262] drm/vkms: Fix flush_work() without INIT_WORK().

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

[ Upstream commit b30b61ff6b1dc37f276cf56a8328b80086a3ffca ]

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: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/vkms/vkms_crtc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
index a0bef7de9df7..1054f535178a 100644
--- a/drivers/gpu/drm/vkms/vkms_crtc.c
+++ b/drivers/gpu/drm/vkms/vkms_crtc.c
@@ -95,6 +95,7 @@ static void vkms_atomic_crtc_reset(struct drm_crtc *crtc)
 	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;
-- 
2.19.1