When the eFuse block covering MT7976C_EFUSE_OFFSET is invalid,
mt7996_mcu_get_eeprom() returns -EINVAL without writing buf, but
mt7996_variant_fem_init() tolerates -EINVAL and keeps running, so
buf[idx] == 0xc reads uninitialized stack memory. A stale 0x0c byte
misclassifies a 0x7976 aDie as 7976C, selects MT7996_FEM_INT and the
wrong default EEPROM, overriding valid calibration data. Only consult
the eFuse byte when the read succeeded; with an invalid eFuse, fall
back to the three explicit aDie version checks.
Fixes: e8cb33ad54 ("wifi: mt76: mt7996: add support for more variants")
Cc: stable@vger.kernel.org
Signed-off-by: Lu Huang <huanglu@kylinos.cn>
Link: https://patch.msgid.link/20260930085435.1424493-1-huanglu@kylinos.cn
Signed-off-by: Felix Fietkau <nbd@nbd.name>
52f6a065e0