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 783FD410D36; Fri, 4 Sep 2026 06:03:43 +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=1788501824; cv=none; b=BcGCknARwP5a/dT7B8q52d8TFTCIBCUqSwmSGiaYMLM+10zLz6kTZJmWenyR+dA/tETCAhLSC4HC7H3G5B8rugdvYYZOuY39xy09zxAT2/GuHk5laTAj05Efks+vSSxaZSE6gHSzWvNBOM2O2yXpd0yMh0hPRgxHADopt9eaU4w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788501824; c=relaxed/simple; bh=s8So7b+RohfWSbSvBo/YsoenvV6/ZbXxx65ESzLkmlg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Xgdc6shUdXO8GpcIHuEk0XXCROeLUCL7TSk5P0CRD7GUYYWRY4DTr9YWx1KQoSXVBwv0vx15m7pw+LN153JdWbP+uWJA1+62Zqpq02azzsRV6IeFVrJwtO6LduIgcwVYUBijOH+KoNUvwoiJr2JSYgwA21b/luP+5i9eeCLs9AU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=lK3AKwpO; 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="lK3AKwpO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C61A81F00A3D; Fri, 4 Sep 2026 06:03:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788501823; bh=RVQ1TgPLz5SMrTyZfU1EskEoVqU6tO6JDv6zcLTZWss=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=lK3AKwpOXB49CSbPXCGNHnIN22miUFmGAJiu19VZb4sbnfmmioBgev3OWtJA3uRTx X5SnR3QGB6wXupmQQEBof2r1kkGJq/TpDyKHiryRpwWXJ3wqGrERdFqNfcRnz0y3/a k0CS8SVVa7ydw3ClbJW+aiDuVKtHGE05a+HjIQSc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jann Horn , Casey Schaufler Subject: [PATCH 6.18 546/552] smack: fix cred UAF in smack_file_send_sigiotask() Date: Fri, 4 Sep 2026 07:01:43 +0200 Message-ID: <20260904045802.980359515@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260904045747.813364717@linuxfoundation.org> References: <20260904045747.813364717@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 6.18-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 @@ -1969,7 +1969,7 @@ 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;