[PATCH v2] mac80211: fix incorrect strlen of .write in debugfs
From: Shayne Chen <shayne.chen@mediatek.com>
Date: 2021-01-12 03:26:41
Also in:
linux-wireless
Subsystem:
mac80211, the rest · Maintainers:
Johannes Berg, Linus Torvalds
This fixes strlen mismatch problems happening in some .write callbacks of debugfs. When trying to configure airtime_flags in debugfs, an error appeared: 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 <redacted> Signed-off-by: Ryder Lee <ryder.lee@mediatek.com> Signed-off-by: Shayne Chen <shayne.chen@mediatek.com> --- v2: - fix r/w buffer OOB - put buf[count] = '\0' to an else --- net/mac80211/debugfs.c | 44 +++++++++++++++++++----------------------- 1 file changed, 20 insertions(+), 24 deletions(-)
diff --git a/net/mac80211/debugfs.c b/net/mac80211/debugfs.c
index 48f144f107d5..9e723d943421 100644
--- a/net/mac80211/debugfs.c
+++ b/net/mac80211/debugfs.c@@ -120,18 +120,17 @@ 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)) + if (count >= sizeof(buf)) return -EINVAL; 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'; + else + buf[count] = '\0'; if (sscanf(buf, "fq_limit %u", &local->fq.limit) == 1) return count;
@@ -177,18 +176,17 @@ 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)) + if (count >= sizeof(buf)) return -EINVAL; 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'; + else + buf[count] = '\0'; if (kstrtou16(buf, 0, &local->airtime_flags)) return -EINVAL;
@@ -237,20 +235,19 @@ 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; - if (count > sizeof(buf)) + if (count >= sizeof(buf)) return -EINVAL; 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'; + else + buf[count] = '\0'; if (sscanf(buf, "%u %u %u", &ac, &q_limit_low, &q_limit_high) != 3) return -EINVAL;
@@ -306,18 +303,17 @@ 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)) + if (count >= sizeof(buf)) return -EINVAL; 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'; + else + buf[count] = '\0'; if (buf[0] == '0' && buf[1] == '\0') local->force_tx_status = 0;
--
2.29.2
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