From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 9844C3B27DB for ; Mon, 27 Jul 2026 15:41:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785166861; cv=none; b=Vfm8R4MHVSMfGmeUI9p1CSY96PMUFwT9zZP9cd+sROFT7xbgaZtrUkHbX/i8NJwz0//LcheK2kLBgzp1UvPjc5aqJoS5n6qOkUX7UUr8W1SgmrJKrA2AoS0+hPc5VjNYeIB9Balb/LEFVdlUA4oFqEBLcQzPzJJZKPHzQsBCkN8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785166861; c=relaxed/simple; bh=MPcCYvOyCvmfxut9ONfVjbfMDO3nZDdz59TURvak+xM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rY3EeIbwkjEEF2PD2DbV+koySuGkZlOfD3mXIN+Sp+Rwyt9Sq06RTzr0hAS8RQqzho1XaSegonHnVKcu26JDlw/xnaxndzFFQLkFALtYU9C73vWHwcNGmyvU1jV76NUGGy6Cl0NPxsIRuChGHh/cqxM1IEBX8XFQRmwRX4iIPqI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=OsxIS2Qt; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="OsxIS2Qt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 976A21F000E9; Mon, 27 Jul 2026 15:40:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785166860; bh=qDkvyFXWfKEUDg3VgDtMD1URPtVpw/j64q9JjMED1fQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=OsxIS2QtV5914jGtl25XMRezeaHSM5Fqe52KFgXrRQJCP2hLf2BJ3YxVSAdUr4avu sseXuxSy8OEEKL8jzasc3tv7Z3ZATHOGd9XZbPaK9yylAHYdL8FQsa3xHNM8/JC54C k7M22HC/NO6naXAqV3+JVVuTPdUx9pnx9ALy3CcuM2g1/KBBacByJH/07GIJdhbzSI JEYqIYXR7fDnxXwiZRyG1xERukdNmKjnMRntMCj4yXzQobNd2gRcwPYqKDS03f36rh n1kpIFzM6cvdE4agi3nuzy+Fh3avGuFzanQtlcZqg+wyGf93zsTI0rWkbkwZ1MajEt +7tu25huMy/GQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Jann Horn , stable@kernel.org, Andrii Nakryiko , Sasha Levin Subject: [PATCH 6.1.y] bpf,fork: wipe ->bpf_storage before bailouts that access it Date: Mon, 27 Jul 2026 11:40:58 -0400 Message-ID: <20260727154058.1514238-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026072029-cringing-silent-7b1b@gregkh> References: <2026072029-cringing-silent-7b1b@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jann Horn [ Upstream commit 9b51a6155d14389876916726430da30eabb1d4ed ] Currently, copy_process() can bail out to free_task() before p->bpf_storage has been initialized, with this call graph (shown here for the !CONFIG_MEMCG case): copy_process dup_task_struct arch_dup_task_struct [copies the entire task_struct, including ->bpf_storage member] [RLIMIT_NPROC check fails] delayed_free_task free_task bpf_task_storage_free rcu_dereference(task->bpf_storage) bpf_local_storage_destroy In this case, the nascent task's ->bpf_storage member that bpf_local_storage_destroy() operates on is a plain copy of the parent's ->bpf_storage pointer, not a real initialized pointer. This leads to badness (kernel hangs, UAF). This is reachable as long as the process calling fork() has been inserted into a task storage map. Cc: stable@kernel.org Fixes: a10787e6d58c ("bpf: Enable task local storage for tracing programs") Signed-off-by: Jann Horn Signed-off-by: Andrii Nakryiko Signed-off-by: Sasha Levin --- kernel/fork.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/fork.c b/kernel/fork.c index db2a9016f636f4..69b62740adc3b5 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1068,6 +1068,10 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node) tsk->reported_split_lock = 0; #endif +#ifdef CONFIG_BPF_SYSCALL + RCU_INIT_POINTER(tsk->bpf_storage, NULL); + tsk->bpf_ctx = NULL; +#endif return tsk; free_stack: @@ -2318,10 +2322,6 @@ static __latent_entropy struct task_struct *copy_process( p->sequential_io = 0; p->sequential_io_avg = 0; #endif -#ifdef CONFIG_BPF_SYSCALL - RCU_INIT_POINTER(p->bpf_storage, NULL); - p->bpf_ctx = NULL; -#endif /* Perform scheduler related setup. Assign this task to a CPU. */ retval = sched_fork(clone_flags, p); -- 2.53.0