From: Pravas Kumar Panda <kumarpan@xxxxxxxxxxxxxx> [ Upstream commit fe0ebb51604f190b13b20a5f6c2821772c0cfc22 ] Before dumping tx_stats proper validation was not been taken care of. Due to which we were encountering null pointer dereference(kernel panic). This scenario will arise when a station is getting disconnected and we are changing the STA state by ath11k_mac_op_sta_state and assigning tx_stats as NULL and after this the mac80211 will destroy the debugfs entry from where we are trying to read the stats. If anyone tries to dump tx_stats for that STA in between setting tx_stats to NULL and debugfs file removal without checking the NULL value it will run into a NULL pointer exception. Proceeding with the analysis of "ARM Kernel Panic". The APSS crash happened due to OOPS on CPU 3. Crash Signature : Unable to handle kernel NULL pointer dereference at virtual address 00000360 During the crash, PC points to "ath11k_debug_htt_stats_init+0x16ac/0x1acc [ath11k]" LR points to "ath11k_debug_htt_stats_init+0x1688/0x1acc [ath11k]". The Backtrace obtained is as follows: [<ffffffbffcfd8590>] ath11k_debug_htt_stats_init+0x16ac/0x1acc [ath11k] [<ffffffc000156320>] do_loop_readv_writev+0x60/0xa4 [<ffffffc000156a5c>] do_readv_writev+0xd8/0x19c [<ffffffc000156b54>] vfs_readv+0x34/0x48 [<ffffffc00017d6f4>] default_file_splice_read+0x1a8/0x2e4 [<ffffffc00017c56c>] do_splice_to+0x78/0x98 [<ffffffc00017c63c>] splice_direct_to_actor+0xb0/0x1a4 [<ffffffc00017c7b4>] do_splice_direct+0x84/0xa8 [<ffffffc000156f40>] do_sendfile+0x160/0x2a4 [<ffffffc000157980>] SyS_sendfile64+0xb4/0xc8 Signed-off-by: Pravas Kumar Panda <kumarpan@xxxxxxxxxxxxxx> Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/net/wireless/ath/ath11k/debugfs_sta.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/net/wireless/ath/ath11k/debugfs_sta.c b/drivers/net/wireless/ath/ath11k/debugfs_sta.c index 743760c9bcae4..e52f3b079bacc 100644 --- a/drivers/net/wireless/ath/ath11k/debugfs_sta.c +++ b/drivers/net/wireless/ath/ath11k/debugfs_sta.c @@ -219,6 +219,9 @@ static ssize_t ath11k_dbg_sta_dump_tx_stats(struct file *file, const int size = 2 * 4096; char *buf; + if (!arsta->tx_stats) + return -ENOENT; + buf = kzalloc(size, GFP_KERNEL); if (!buf) return -ENOMEM; -- 2.20.1
