This fixes strlen mismatch problems happening in some .write callbacks of debugfs. When trying to configure airtime_flags in debugfs, an error appeared: # echo 0 > /sys/kernel/debug/ieee80211/phy0/airtime_flags ash: write error: Invalid argument The error is returned from kstrtou16() since a wrong length makes it miss the real end of input string. To fix this, use count as the string length, and set proper end of string for a char buffer. The debug print is shown - airtime_flags_write: count = 2, len = 8, where the actual length is 2, but "len = strlen(buf)" gets 8. Also cleanup the other similar cases for the sake of consistency. Signed-off-by: Sujuan Chen <sujuan.chen@xxxxxxxxxxxx> Signed-off-by: Ryder Lee <ryder.lee@xxxxxxxxxxxx> Signed-off-by: Shayne Chen <shayne.chen@xxxxxxxxxxxx> --- This patch is based on the discussion from https://patchwork.kernel.org/project/linux-wireless/list/?series=409693 --- net/mac80211/debugfs.c | 36 ++++++++++++++++-------------------- 1 file changed, 16 insertions(+), 20 deletions(-) diff --git a/net/mac80211/debugfs.c b/net/mac80211/debugfs.c index 9135b6f..9991a6a 100644 --- a/net/mac80211/debugfs.c +++ b/net/mac80211/debugfs.c @@ -120,7 +120,6 @@ static ssize_t aqm_write(struct file *file, { struct ieee80211_local *local = file->private_data; char buf[100]; - size_t len; if (count > sizeof(buf)) return -EINVAL; @@ -128,10 +127,10 @@ static ssize_t aqm_write(struct file *file, if (copy_from_user(buf, user_buf, count)) return -EFAULT; - buf[sizeof(buf) - 1] = '\0'; - len = strlen(buf); - if (len > 0 && buf[len-1] == '\n') - buf[len-1] = 0; + if (count && buf[count - 1] == '\n') + buf[count - 1] = '\0'; + + buf[count] = '\0'; if (sscanf(buf, "fq_limit %u", &local->fq.limit) == 1) return count; @@ -177,7 +176,6 @@ static ssize_t airtime_flags_write(struct file *file, { struct ieee80211_local *local = file->private_data; char buf[16]; - size_t len; if (count > sizeof(buf)) return -EINVAL; @@ -185,10 +183,10 @@ static ssize_t airtime_flags_write(struct file *file, if (copy_from_user(buf, user_buf, count)) return -EFAULT; - buf[sizeof(buf) - 1] = 0; - len = strlen(buf); - if (len > 0 && buf[len - 1] == '\n') - buf[len - 1] = 0; + if (count && buf[count - 1] == '\n') + buf[count - 1] = '\0'; + + buf[count] = '\0'; if (kstrtou16(buf, 0, &local->airtime_flags)) return -EINVAL; @@ -237,7 +235,6 @@ static ssize_t aql_txq_limit_write(struct file *file, { struct ieee80211_local *local = file->private_data; char buf[100]; - size_t len; u32 ac, q_limit_low, q_limit_high, q_limit_low_old, q_limit_high_old; struct sta_info *sta; @@ -247,10 +244,10 @@ static ssize_t aql_txq_limit_write(struct file *file, if (copy_from_user(buf, user_buf, count)) return -EFAULT; - buf[sizeof(buf) - 1] = 0; - len = strlen(buf); - if (len > 0 && buf[len - 1] == '\n') - buf[len - 1] = 0; + if (count && buf[count - 1] == '\n') + buf[count - 1] = '\0'; + + buf[count] = '\0'; if (sscanf(buf, "%u %u %u", &ac, &q_limit_low, &q_limit_high) != 3) return -EINVAL; @@ -306,7 +303,6 @@ static ssize_t force_tx_status_write(struct file *file, { struct ieee80211_local *local = file->private_data; char buf[3]; - size_t len; if (count > sizeof(buf)) return -EINVAL; @@ -314,10 +310,10 @@ static ssize_t force_tx_status_write(struct file *file, if (copy_from_user(buf, user_buf, count)) return -EFAULT; - buf[sizeof(buf) - 1] = '\0'; - len = strlen(buf); - if (len > 0 && buf[len - 1] == '\n') - buf[len - 1] = 0; + if (count && buf[count - 1] == '\n') + buf[count - 1] = '\0'; + + buf[count] = '\0'; if (buf[0] == '0' && buf[1] == '\0') local->force_tx_status = 0; -- 2.29.2
