thunderbolt: Fix NULL dereference in tb_remove_work()grafted

There is a slight race between tb_remove_work() and tb_domain_remove()
which leads to dereferencing a NULL tb->root_switch pointer inside
tb_free_unplugged_xdomains():

        Thread A                            Thread B

  tb_remove_work()
                                    tb_domain_remove()
                                      mutex_lock(&tb->lock)
                                      tb_stop()
                                        /* doesn't cancel a running callback */
                                        cancel_delayed_work(&tcm->remove_work)
                                        ...
                                        tb_switch_remove(tb->root_switch)
                                        tb->root_switch = NULL
                                      mutex_unlock(&tb->lock)
    mutex_lock(&tb->lock)
    ...
    /* without checking ->root_switch */
    tb_free_unplugged_xdomains(tb->root_switch)
    mutex_unlock(&tb->lock)

Commit a8937f35cf39 ("thunderbolt: Remove XDomain from the bus without
holding tb->lock") doesn't seem right to move tb_free_unplugged_xdomains()
out of the &tb->lock section and the check for tb->root_switch, in
particular.  It states:

  For this reason separate removing the XDomain from the topology data
  structures (where we need the lock) from unregistering the device from
  the bus (where remove callbacks of the drivers are being called).

tb_free_unplugged_xdomains() belongs to the former group of functions
requiring the lock.  And it also calls tb_xdomain_remove() which should
only be called with &tb->lock held.

Found by Linux Verification Center (linuxtesting.org) with Svace static
analysis tool.

Fixes: a8937f35cf39 ("thunderbolt: Remove XDomain from the bus without holding tb->lock")
Cc: stable@vger.kernel.org
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/include/media/jpeg.h b/include/media/jpeg.h
new file mode 100644
index 000000000..a01e142e9
--- /dev/null
+++ b/include/media/jpeg.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef _MEDIA_JPEG_H_
+#define _MEDIA_JPEG_H_
+
+/* JPEG markers */
+#define JPEG_MARKER_TEM		0x01
+#define JPEG_MARKER_SOF0	0xc0
+#define JPEG_MARKER_DHT		0xc4
+#define JPEG_MARKER_RST		0xd0
+#define JPEG_MARKER_SOI		0xd8
+#define JPEG_MARKER_EOI		0xd9
+#define JPEG_MARKER_SOS		0xda
+#define JPEG_MARKER_DQT		0xdb
+#define JPEG_MARKER_DRI		0xdd
+#define JPEG_MARKER_DHP		0xde
+#define JPEG_MARKER_APP0	0xe0
+#define JPEG_MARKER_COM		0xfe
+
+#endif /* _MEDIA_JPEG_H_ */