[PATCH] wifi: cisco: do not assign -1 to unsigned char

[PATCH] wifi: cisco: do not assign -1 to unsigned char

[Jason A. Donenfeld]

With char becoming unsigned by default, and with `char` alone being
ambiguous and based on architecture, we get a warning when assigning the
unchecked output of hex_to_bin() to that unsigned char. Mark `key` as a
`u8`, which matches the struct's type, and then check each call to
hex_to_bin() before casting.

Cc: Kalle Valo <kvalo@kernel.org>
Cc: linux-wireless@vger.kernel.org
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 drivers/net/wireless/cisco/airo.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/cisco/airo.c b/drivers/net/wireless/cisco/airo.c
index 10daef81c355..fb2c35bd73bb 100644
--- a/drivers/net/wireless/cisco/airo.c
+++ b/drivers/net/wireless/cisco/airo.c
@@ -5232,7 +5232,7 @@ static int get_wep_tx_idx(struct airo_info *ai)
 	return -1;
 }
 
-static int set_wep_key(struct airo_info *ai, u16 index, const char *key,
+static int set_wep_key(struct airo_info *ai, u16 index, const u8 *key,
 		       u16 keylen, int perm, int lock)
 {
 	static const unsigned char macaddr[ETH_ALEN] = { 0x01, 0, 0, 0, 0, 0 };
@@ -5283,7 +5283,7 @@ static void proc_wepkey_on_close(struct inode *inode, struct file *file)
 	struct net_device *dev = pde_data(inode);
 	struct airo_info *ai = dev->ml_priv;
 	int i, rc;
-	char key[16];
+	u8 key[16];
 	u16 index = 0;
 	int j = 0;
 
@@ -5311,12 +5311,22 @@ static void proc_wepkey_on_close(struct inode *inode, struct file *file)
 	}
 
 	for (i = 0; i < 16*3 && data->wbuffer[i+j]; i++) {
+		int val;
+
+		if (i % 3 == 2)
+			continue;
+
+		val = hex_to_bin(data->wbuffer[i+j]);
+		if (val < 0) {
+			airo_print_err(ai->dev->name, "WebKey passed invalid key hex");
+			return;
+		}
 		switch(i%3) {
 		case 0:
-			key[i/3] = hex_to_bin(data->wbuffer[i+j])<<4;
+			key[i/3] = (u8)val << 4;
 			break;
 		case 1:
-			key[i/3] |= hex_to_bin(data->wbuffer[i+j]);
+			key[i/3] |= (u8)val;
 			break;
 		}
 	}
-- 
2.38.1

RE: [PATCH] wifi: cisco: do not assign -1 to unsigned char

[David Laight]

From: Jason A. Donenfeld
> Sent: 24 October 2022 17:29
> 
> With char becoming unsigned by default, and with `char` alone being
> ambiguous and based on architecture, we get a warning when assigning the
> unchecked output of hex_to_bin() to that unsigned char. Mark `key` as a
> `u8`, which matches the struct's type, and then check each call to
> hex_to_bin() before casting.
> 
> Cc: Kalle Valo <kvalo@kernel.org>
> Cc: linux-wireless@vger.kernel.org
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> ---
>  drivers/net/wireless/cisco/airo.c | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/wireless/cisco/airo.c b/drivers/net/wireless/cisco/airo.c
> index 10daef81c355..fb2c35bd73bb 100644
> --- a/drivers/net/wireless/cisco/airo.c
> +++ b/drivers/net/wireless/cisco/airo.c
> @@ -5232,7 +5232,7 @@ static int get_wep_tx_idx(struct airo_info *ai)
>  	return -1;
>  }
> 
> -static int set_wep_key(struct airo_info *ai, u16 index, const char *key,
> +static int set_wep_key(struct airo_info *ai, u16 index, const u8 *key,
>  		       u16 keylen, int perm, int lock)
>  {
>  	static const unsigned char macaddr[ETH_ALEN] = { 0x01, 0, 0, 0, 0, 0 };
> @@ -5283,7 +5283,7 @@ static void proc_wepkey_on_close(struct inode *inode, struct file *file)
>  	struct net_device *dev = pde_data(inode);
>  	struct airo_info *ai = dev->ml_priv;
>  	int i, rc;
> -	char key[16];
> +	u8 key[16];
>  	u16 index = 0;
>  	int j = 0;
> 
> @@ -5311,12 +5311,22 @@ static void proc_wepkey_on_close(struct inode *inode, struct file *file)
>  	}
> 
>  	for (i = 0; i < 16*3 && data->wbuffer[i+j]; i++) {
> +		int val;
> +
> +		if (i % 3 == 2)
> +			continue;
> +
> +		val = hex_to_bin(data->wbuffer[i+j]);
> +		if (val < 0) {
> +			airo_print_err(ai->dev->name, "WebKey passed invalid key hex");
> +			return;
> +		}
>  		switch(i%3) {
>  		case 0:
> -			key[i/3] = hex_to_bin(data->wbuffer[i+j])<<4;
> +			key[i/3] = (u8)val << 4;
>  			break;
>  		case 1:
> -			key[i/3] |= hex_to_bin(data->wbuffer[i+j]);
> +			key[i/3] |= (u8)val;
>  			break;
>  		}
>  	}

That is about the crappiest loop I've seen.
I was just going to point out that the (u8) casts aren't needed.
Something like:
	for (i = 0, buf = data->wbuffer + j; i < 16; i++, buf += 3) {
		int val;
		if (!buf[0] || !buf[1])
			break;
		val = hex_to_bin(buf[0]) | hex_to_bin(buf[1]) << 8;
		if (val < 0) {
			airo_print_err(ai->dev->name, "WebKey passed invalid key hex");
			return;
		}
		key[i] = val;
		if (!buf[2])
			break;
	}

Although there should be a check for buf[2] being valid.
Any I worry about exactly what happens if there aren't 16 full bytes.

	David

		

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

Re: [PATCH] wifi: cisco: do not assign -1 to unsigned char

[Jason A. Donenfeld]

On Tue, Oct 25, 2022 at 10:11:44AM +0000, David Laight wrote:
> From: Jason A. Donenfeld
> > Sent: 24 October 2022 17:29
> > 
> > With char becoming unsigned by default, and with `char` alone being
> > ambiguous and based on architecture, we get a warning when assigning the
> > unchecked output of hex_to_bin() to that unsigned char. Mark `key` as a
> > `u8`, which matches the struct's type, and then check each call to
> > hex_to_bin() before casting.
> > 
> > Cc: Kalle Valo <kvalo@kernel.org>
> > Cc: linux-wireless@vger.kernel.org
> > Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> > ---
> >  drivers/net/wireless/cisco/airo.c | 18 ++++++++++++++----
> >  1 file changed, 14 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/net/wireless/cisco/airo.c b/drivers/net/wireless/cisco/airo.c
> > index 10daef81c355..fb2c35bd73bb 100644
> > --- a/drivers/net/wireless/cisco/airo.c
> > +++ b/drivers/net/wireless/cisco/airo.c
> > @@ -5232,7 +5232,7 @@ static int get_wep_tx_idx(struct airo_info *ai)
> >  	return -1;
> >  }
> > 
> > -static int set_wep_key(struct airo_info *ai, u16 index, const char *key,
> > +static int set_wep_key(struct airo_info *ai, u16 index, const u8 *key,
> >  		       u16 keylen, int perm, int lock)
> >  {
> >  	static const unsigned char macaddr[ETH_ALEN] = { 0x01, 0, 0, 0, 0, 0 };
> > @@ -5283,7 +5283,7 @@ static void proc_wepkey_on_close(struct inode *inode, struct file *file)
> >  	struct net_device *dev = pde_data(inode);
> >  	struct airo_info *ai = dev->ml_priv;
> >  	int i, rc;
> > -	char key[16];
> > +	u8 key[16];
> >  	u16 index = 0;
> >  	int j = 0;
> > 
> > @@ -5311,12 +5311,22 @@ static void proc_wepkey_on_close(struct inode *inode, struct file *file)
> >  	}
> > 
> >  	for (i = 0; i < 16*3 && data->wbuffer[i+j]; i++) {
> > +		int val;
> > +
> > +		if (i % 3 == 2)
> > +			continue;
> > +
> > +		val = hex_to_bin(data->wbuffer[i+j]);
> > +		if (val < 0) {
> > +			airo_print_err(ai->dev->name, "WebKey passed invalid key hex");
> > +			return;
> > +		}
> >  		switch(i%3) {
> >  		case 0:
> > -			key[i/3] = hex_to_bin(data->wbuffer[i+j])<<4;
> > +			key[i/3] = (u8)val << 4;
> >  			break;
> >  		case 1:
> > -			key[i/3] |= hex_to_bin(data->wbuffer[i+j]);
> > +			key[i/3] |= (u8)val;
> >  			break;
> >  		}
> >  	}
> 
> That is about the crappiest loop I've seen.
> I was just going to point out that the (u8) casts aren't needed.
> Something like:
> 	for (i = 0, buf = data->wbuffer + j; i < 16; i++, buf += 3) {
> 		int val;
> 		if (!buf[0] || !buf[1])
> 			break;
> 		val = hex_to_bin(buf[0]) | hex_to_bin(buf[1]) << 8;
> 		if (val < 0) {
> 			airo_print_err(ai->dev->name, "WebKey passed invalid key hex");
> 			return;
> 		}
> 		key[i] = val;
> 		if (!buf[2])
> 			break;
> 	}
> 
> Although there should be a check for buf[2] being valid.
> Any I worry about exactly what happens if there aren't 16 full bytes.

buf[2] isn't checked. Presumably it's a space or something. Your <<8
also isn't right; this is a hex char. Anyway, I think I'd rather
minimize this delta and leave this patch as-is.

Jason

Re: wifi: airo: do not assign -1 to unsigned char

[Kalle Valo]

"Jason A. Donenfeld" <Jason@zx2c4.com> wrote:

> With char becoming unsigned by default, and with `char` alone being
> ambiguous and based on architecture, we get a warning when assigning the
> unchecked output of hex_to_bin() to that unsigned char. Mark `key` as a
> `u8`, which matches the struct's type, and then check each call to
> hex_to_bin() before casting.
> 
> Cc: Kalle Valo <kvalo@kernel.org>
> Cc: linux-wireless@vger.kernel.org
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

Patch applied to wireless.git, thanks.

e6cb8769452e wifi: airo: do not assign -1 to unsigned char

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20221024162843.535921-1-Jason@zx2c4.com/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches