[PATCH 4.4 79/86] thunderbolt: Fix double free of drom buffer

[Greg Kroah-Hartman]

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

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

From: Andreas Noever <andreas.noever@xxxxxxxxx>

commit 2ffa9a5d76a75abbc1f95c17959fced666095bdd upstream.

If tb_drom_read() fails, sw->drom is freed but not set to NULL.  sw->drom
is then freed again in the error path of tb_switch_alloc().

The bug can be triggered by unplugging a thunderbolt device shortly after
it is detected by the thunderbolt driver.

Clear sw->drom if tb_drom_read() fails.

[bhelgaas: add Fixes:, stable versions of interest]
Fixes: 343fcb8c70d7 ("thunderbolt: Fix nontrivial endpoint devices.")
Signed-off-by: Andreas Noever <andreas.noever@xxxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
CC: Lukas Wunner <lukas@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/thunderbolt/eeprom.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/thunderbolt/eeprom.c
+++ b/drivers/thunderbolt/eeprom.c
@@ -444,6 +444,7 @@ int tb_drom_read(struct tb_switch *sw)
 	return tb_drom_parse_entries(sw);
 err:
 	kfree(sw->drom);
+	sw->drom = NULL;
 	return -EIO;
 
 }