On 2/21/22 13:22, Dan Carpenter wrote:
On Sun, Feb 20, 2022 at 05:30:08PM +0100, Michael Straube wrote:
On 2/20/22 17:20, Pavel Skripkin wrote:
Hi Michael,
On 2/20/22 18:48, Michael Straube wrote:
-static int ch_freq_map_num = ARRAY_SIZE(ch_freq_map);
-
u32 rtw_ch2freq(u32 channel)
{
- u8 i;
- u32 freq = 0;
-
- for (i = 0; i < ch_freq_map_num; i++) {
- if (channel == ch_freq_map[i].channel) {
- freq = ch_freq_map[i].frequency;
- break;
- }
- }
- if (i == ch_freq_map_num)
- freq = 2412;
-
- return freq;
+ return ch_freq_map[channel - 1];
}
What if channel has wrong value? The old code returned some default
value, but with new one we will hit OOB.
Hi Pavel,
thanks for reviewing. Yeah, I thought about adding a check for channel
value between 1 and 14. But I did not add it because I think if this
function will ever be called with channel < 1 or channel > 14, then the
calling code must be wrong.
Would be nice to see what others think about this.
I'm glad that Pavel noticed this change. This is a risky thing and
should have been noted in the commit message.
Just from a review stand point it would be best to leave the original
behavior.
Do you mean to leave the whole original code including the 5 GHz
frequencies? Or returning a default value if we have a channel value < 1
or > 14?
I'm a bit confused now, because Greg asked how we know that the driver
is only for 2.4 GHz chips.
I have audited this change and I do not think it is safe. It seems to
me that one way this can be controlled is via
module_param(rtw_channel, int, 0644); in
drivers/staging/r8188eu/os_dep/os_intfs.c. I don't see any checking on
that.
Thank you Dan!
I missed that and blindly assumed the function will never be called
with channel values OOB. That was not good, sorry.
regards,
Michael
