Hassan bin Atiyyah (may Allah have mercy on him) narrates from Sayyiduna Abu Waqid al-Laythi (may Allah be pleased with him) that we said to the Messenger of Allah (peace and blessings be upon him): If hunger afflicts us in some land, when is eating carrion lawful? He said: "When you find neither morning nor evening food, nor vegetables, then eating carrion is permissible for you."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19637