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Subject[PATCH 5.10 32/57] mac80211: fix incorrect strlen of .write in debugfs
Date
From: Shayne Chen <shayne.chen@mediatek.com>

[ Upstream commit 6020d534fa012b80c6d13811dc4d2dfedca2e403 ]

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 <sujuan.chen@mediatek.com>
Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
Link: https://lore.kernel.org/r/20210112032028.7482-1-shayne.chen@mediatek.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 90470392fdaa7..de5cd3818690c 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;
--
2.27.0


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