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Donenfeld" To: David Laight Cc: "linux-kernel@vger.kernel.org" , Kalle Valo , "linux-wireless@vger.kernel.org" Subject: Re: [PATCH] wifi: cisco: do not assign -1 to unsigned char Message-ID: References: <20221024162843.535921-1-Jason@zx2c4.com> <6a1652ab408d4c5d8ba754f35680e792@AcuMS.aculab.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <6a1652ab408d4c5d8ba754f35680e792@AcuMS.aculab.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > > Cc: linux-wireless@vger.kernel.org > > Signed-off-by: Jason A. Donenfeld > > --- > > 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