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 7D19A42376F; Fri, 4 Sep 2026 06:23:07 +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=1788502988; cv=none; b=lX5IUyaBdTmEaYipDBR3xiwTS2HOMpYaecsnXGP70D5dYakpUKX4ldZlULt1yN7vAOSFKPy7/zlKIPxtsLu2nyEwWxMok6gCvQPaji+Oe7dGZx5ev/M2yCygKjAeoJe92r7QlqzWHj/1sRQmAGmih3hLrExYIVUlAzj+8SQ3L7U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788502988; c=relaxed/simple; bh=DtBbvZMoDdGh/d/uERHglGJhQeA4ADQIVKP7yZP0j/0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=o2mVtbMoMuGJ+GVp/ecHVCXgLM9uSMX/bwdTiWolGSPVapA0AHrtiUCnjSAu4Ig4v6g53v0vvpRBjse2nM5IUReK5uNxLRu326WPKHVrKyCD8+OgNyyzso1XIX/m26S+hS6APNoILZwAVOwmh4QvLr5F7fCFxiNbJ+nXHS5HcTs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=h0acoD0D; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="h0acoD0D" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D53F61F00A3F; Fri, 4 Sep 2026 06:23:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788502987; bh=Jhad7k+FCR2t1O/77fE4nTJ2KWGRHEmvZrDUQ95pgXk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=h0acoD0DfMBFE9BxFoPBtPeHA/QUY6R5ExTpOMo+Xc/hZNvDCs5uDjSTnomYSbUD0 66+byzdbFdA5MuIchaaM0AwSNfYq5bQSLET49U209nAzBDRT0xcKhkGrokz3Xm5UFd YowHbH0OZlCnlPHgDs9/ylAZl42d47Z/F+59ZQrM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jann Horn , Casey Schaufler Subject: [PATCH 6.12 399/403] smack: fix cred UAF in smack_file_send_sigiotask() Date: Fri, 4 Sep 2026 07:03:22 +0200 Message-ID: <20260904045743.852626111@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260904045734.806166532@linuxfoundation.org> References: <20260904045734.806166532@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jann Horn commit fedc88e38ce979a720cd2de042578cb5df3dc8de upstream. When inspecting the credentials of another task, objective credentials (->real_cred, accessed with __task_cred()) must always be used. Accessing ->cred on a non-current task is forbidden unless that task is being created or destroyed; a task is allowed to change its own ->cred pointer with no synchronization, and changing ->cred should only affect the current syscall. smack_file_send_sigiotask() was accessing both sets of credentials: First tsk->cred, then __task_cred(tsk). Fix it, always access the objective credentials here. I have tested that this bug can lead to a KASAN-reported UAF of struct cred in smack_file_send_sigiotask(), and that this fix prevents the race. Cc: stable@vger.kernel.org Signed-off-by: Jann Horn Signed-off-by: Casey Schaufler Signed-off-by: Greg Kroah-Hartman --- security/smack/smack_lsm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -1988,7 +1988,7 @@ static int smack_file_send_sigiotask(str { struct smack_known **blob; struct smack_known *skp; - struct smack_known *tkp = smk_of_task(smack_cred(tsk->cred)); + struct smack_known *tkp = smk_of_task_struct_obj(tsk); const struct cred *tcred; struct file *file; int rc;