Question about missing variable assignment

Hi all,

The following piece of code in drivers/net/wireless/mediatek/mt76/mt7603/mac.c is missing a variable assignment before line 1058. Notice that there is a potential execution path in which variable *i* is compared against magic number 15 at line 1075 without being initialized previously (this was reported by Coverity):

1055 out:
1056 final_rate_flags = info->status.rates[final_idx].flags;
1057
1058 switch (FIELD_GET(MT_TX_RATE_MODE, final_rate)) {
1059 case MT_PHY_TYPE_CCK:
1060 cck = true;
1061 /* fall through */
1062 case MT_PHY_TYPE_OFDM:
1063 if (dev->mt76.chandef.chan->band == NL80211_BAND_5GHZ)
1064 sband = &dev->mt76.sband_5g.sband;
1065 else
1066 sband = &dev->mt76.sband_2g.sband;

1067                 final_rate &= GENMASK(5, 0);
1068                 final_rate = mt7603_get_rate(dev, sband, final_rate, cck);
1069                 final_rate_flags = 0;
1070                 break;
1071         case MT_PHY_TYPE_HT_GF:
1072         case MT_PHY_TYPE_HT:
1073                 final_rate_flags |= IEEE80211_TX_RC_MCS;
1074                 final_rate &= GENMASK(5, 0);
1075                 if (i > 15)

1076 return false;
1077 break;
1078 default:
1079 return false;
1080 }

My guess is that such missing assignment should be something similar to the one at line 566:

	i = FIELD_GET(MT_RXV1_TX_RATE, rxdg0);

but I'm not sure what the proper arguments for macro FIELD_GET should be.

This code was introduced by commit c8846e1015022d2531ac4c895783e400b3e5babe

What do you think?

Quoted 43 lines · Gustavo A. R. Silva

Hi all,

The following piece of code in drivers/net/wireless/mediatek/mt76/mt7603/mac.c is missing a variable assignment before line 1058. Notice that there is a potential execution path in which variable *i* is compared against magic number 15 at line 1075 without being initialized previously (this was reported by Coverity):

1055 out:
1056 final_rate_flags = info->status.rates[final_idx].flags;
1057
1058 switch (FIELD_GET(MT_TX_RATE_MODE, final_rate)) {
1059 case MT_PHY_TYPE_CCK:
1060 cck = true;
1061 /* fall through */
1062 case MT_PHY_TYPE_OFDM:
1063 if (dev->mt76.chandef.chan->band == NL80211_BAND_5GHZ)
1064 sband = &dev->mt76.sband_5g.sband;
1065 else
1066 sband = &dev->mt76.sband_2g.sband;

1067                 final_rate &= GENMASK(5, 0);
1068                 final_rate = mt7603_get_rate(dev, sband, final_rate, cck);
1069                 final_rate_flags = 0;
1070                 break;
1071         case MT_PHY_TYPE_HT_GF:
1072         case MT_PHY_TYPE_HT:
1073                 final_rate_flags |= IEEE80211_TX_RC_MCS;
1074                 final_rate &= GENMASK(5, 0);
1075                 if (i > 15)

1076 return false;
1077 break;
1078 default:
1079 return false;
1080 }

My guess is that such missing assignment should be something similar to the one at line 566:

	i = FIELD_GET(MT_RXV1_TX_RATE, rxdg0);

but I'm not sure what the proper arguments for macro FIELD_GET should be.

Quoted 3 lines

This code was introduced by commit c8846e1015022d2531ac4c895783e400b3e5babe

What do you think?

Thanks for reporting this. The fix is simpler than that, the check should be: if (final_rate > 15)
I will send a fix.