iwlwifi: iwl-dbg: Use del_timer_sync() before freeing

[ Upstream commit 7635a1ad8d92dcc8247b53f949e37795154b5b6f ]

In Chrome OS, a large number of crashes is observed due to corrupted timer
lists. Steven Rostedt pointed out that this usually happens when a timer
is freed while still active, and that the problem is often triggered
by code calling del_timer() instead of del_timer_sync() just before
freeing.

Steven also identified the iwlwifi driver as one of the possible culprits
since it does exactly that.

Reported-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Johannes Berg <johannes.berg@intel.com>
Cc: Gregory Greenman <gregory.greenman@intel.com>
Fixes: 60e8abd9d3e91 ("iwlwifi: dbg_ini: add periodic trigger new API support")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Gregory Greenman <gregory.greenman@intel.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # Linux v5.17.3-rc1 and Debian LLVM-14
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220411154210.1870008-1-linux@roeck-us.net
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c b/drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c
index 125479b..fc4197b 100644 (file)
--- a/drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c
+++ b/drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c
@@ -322,7 +322,7 @@ void iwl_dbg_tlv_del_timers(struct iwl_trans *trans)
        struct iwl_dbg_tlv_timer_node *node, *tmp;
 
        list_for_each_entry_safe(node, tmp, timer_list, list) {
-               del_timer(&node->timer);
+               del_timer_sync(&node->timer);
                list_del(&node->list);
                kfree(node);
        }