From fe0ebb51604f190b13b20a5f6c2821772c0cfc22 Mon Sep 17 00:00:00 2001 From: Pravas Kumar Panda Date: Tue, 17 Mar 2020 17:29:29 +0530 Subject: [PATCH] ath11k: Adding proper validation before accessing tx_stats 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: [] ath11k_debug_htt_stats_init+0x16ac/0x1acc [ath11k] [] do_loop_readv_writev+0x60/0xa4 [] do_readv_writev+0xd8/0x19c [] vfs_readv+0x34/0x48 [] default_file_splice_read+0x1a8/0x2e4 [] do_splice_to+0x78/0x98 [] splice_direct_to_actor+0xb0/0x1a4 [] do_splice_direct+0x84/0xa8 [] do_sendfile+0x160/0x2a4 [] SyS_sendfile64+0xb4/0xc8 Signed-off-by: Pravas Kumar Panda Signed-off-by: Kalle Valo --- 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 872f3ef4d2a8..389dac219238 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; -- 2.17.1