From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail3-165.sinamail.sina.com.cn (mail3-165.sinamail.sina.com.cn [202.108.3.165]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 12FD61FE451 for ; Wed, 11 Feb 2026 00:38:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=202.108.3.165 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770770320; cv=none; b=dZuupeecfHeqsH5mT01qKVk07+kF91D32HZ69m9odiGV50HbkxMalBY5hnQtlQV+bR3zT5aVM/rXPoPBVrhROjMIoRCAtDzssjr4orBHwAl5U0uj94gw8gFSXaKNfKpdolK1C+iSbMebbbRL8rsYaQIQ4AZ2r4Ux2EDfachYJU0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770770320; c=relaxed/simple; bh=eBrqBwZVJGw7c6IuxeO/AFOhmFE4L9nYO13n//fOxfk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MOtd6qCXh6QUnS7/qxILhcsQVxNbnQxwTNELNXd7YQVQqT1n8dnCpYV0PE9DbUN318qGwAF3FaMGQs7PFNrO4jPk1E2KcIigMmnegtifkxZU/Vmd/koOaYj1fZzS64g07rxnFei1kzV4w6s8VUoul6Qmjmnc46erSyhO5NU72hY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com; spf=pass smtp.mailfrom=sina.com; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b=xTh0P2Ba; arc=none smtp.client-ip=202.108.3.165 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sina.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b="xTh0P2Ba" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sina.com; s=201208; t=1770770317; bh=QovdLr/lushu3Wkc+mSaIyo/kZgEaDdW0plRRWrdTnA=; h=From:Subject:Date:Message-ID; b=xTh0P2Bag1N4ta4Oas3vSqJCL7tNdnBwvJd1aV/vCaZrvglgBaInKP6r/2RAtfiZI Xp3wV5/QvYDKPfKxG+yK2Gc1LNCzXABbtABysFfJsV5viJHOPkr/kmeFJn4TVpg6sK kyMMCG6rgFLl07pOOQUbRr+lZAAyouVCTo8G9pU4= X-SMAIL-HELO: localhost.localdomain Received: from unknown (HELO localhost.localdomain)([114.249.62.144]) by sina.com (10.54.253.33) with ESMTP id 698BCF820000415D; Wed, 11 Feb 2026 08:38:28 +0800 (CST) X-Sender: hdanton@sina.com X-Auth-ID: hdanton@sina.com Authentication-Results: sina.com; spf=none smtp.mailfrom=hdanton@sina.com; dkim=none header.i=none; dmarc=none action=none header.from=hdanton@sina.com X-SMAIL-MID: 1897416685188 X-SMAIL-UIID: E85B052D4D464F06B5357D7326728DC5-20260211-083828-1 From: Hillf Danton To: syzbot Cc: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [kernel?] KASAN: slab-use-after-free Read in futex_unqueue Date: Wed, 11 Feb 2026 08:38:15 +0800 Message-ID: <20260211003816.2861-1-hdanton@sina.com> In-Reply-To: <698ba684.a70a0220.2c38d7.007c.GAE@google.com> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit > Date: Tue, 10 Feb 2026 13:43:32 -0800 [thread overview] > Hello, > > syzbot found the following issue on: > > HEAD commit: 72c395024dac Merge tag 'docs-7.0' of git://git.kernel.org/.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=137d9b22580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=bf83be18dae53c93 > dashboard link: https://syzkaller.appspot.com/bug?extid=6c1861115b4253e45969 > compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=169f8ae6580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17f657fa580000 #syz test --- x/kernel/futex/core.c +++ y/kernel/futex/core.c @@ -1735,8 +1735,7 @@ void futex_hash_free(struct mm_struct *m free_percpu(mm->futex_ref); kvfree(mm->futex_phash_new); fph = rcu_dereference_raw(mm->futex_phash); - if (fph) - kvfree(fph); + kvfree_rcu(fph, rcu); } static bool futex_pivot_pending(struct mm_struct *mm) --- x/kernel/fork.c +++ y/kernel/fork.c @@ -1192,6 +1192,7 @@ static inline void __mmput(struct mm_str void mmput(struct mm_struct *mm) { might_sleep(); + VM_BUG_ON(!atomic_read(&mm->mm_users)); if (atomic_dec_and_test(&mm->mm_users)) __mmput(mm); --