From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 CFC8A1C31 for ; Wed, 23 Nov 2022 09:58:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 363E2C433D7; Wed, 23 Nov 2022 09:58:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1669197529; bh=RPG5qSX8gxOwT9HLzoJMVEcJ0jf9kOO4VChFLrKV11o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=G7eTVjAPJUbng/MzAKMUFTTWQ6u6ngUcVUnDMkg0aO+x20lPuJqrfgqRSdgfTQ/+f kS+KOeVVtvl8hbtTm918G1KIvVD/uSAEtlQ5y7RzaLa/Iz1AjLpOBh6er9xJCRxk17 5RwCAJ6vQv6tkd/IXjzvCWMFj03hSZM+p8GjyRw0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mark Rutland , Mathieu Desnoyers , "Peter Zijlstra (Intel)" , "Paul E. McKenney" Subject: [PATCH 6.0 308/314] rseq: Use pr_warn_once() when deprecated/unknown ABI flags are encountered Date: Wed, 23 Nov 2022 09:52:33 +0100 Message-Id: <20221123084639.525039336@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221123084625.457073469@linuxfoundation.org> References: <20221123084625.457073469@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Mathieu Desnoyers commit 448dca8c88755b768552e19bd1618be34ef6d1ff upstream. These commits use WARN_ON_ONCE() and kill the offending processes when deprecated and unknown flags are encountered: commit c17a6ff93213 ("rseq: Kill process when unknown flags are encountered in ABI structures") commit 0190e4198e47 ("rseq: Deprecate RSEQ_CS_FLAG_NO_RESTART_ON_* flags") The WARN_ON_ONCE() triggered by userspace input prevents use of Syzkaller to fuzz the rseq system call. Replace this WARN_ON_ONCE() by pr_warn_once() messages which contain actually useful information. Reported-by: Mark Rutland Signed-off-by: Mathieu Desnoyers Signed-off-by: Peter Zijlstra (Intel) Acked-by: Mark Rutland Acked-by: Paul E. McKenney Link: https://lkml.kernel.org/r/20221102130635.7379-1-mathieu.desnoyers@efficios.com Signed-off-by: Greg Kroah-Hartman --- kernel/rseq.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) --- a/kernel/rseq.c +++ b/kernel/rseq.c @@ -171,12 +171,27 @@ static int rseq_get_rseq_cs(struct task_ return 0; } +static bool rseq_warn_flags(const char *str, u32 flags) +{ + u32 test_flags; + + if (!flags) + return false; + test_flags = flags & RSEQ_CS_NO_RESTART_FLAGS; + if (test_flags) + pr_warn_once("Deprecated flags (%u) in %s ABI structure", test_flags, str); + test_flags = flags & ~RSEQ_CS_NO_RESTART_FLAGS; + if (test_flags) + pr_warn_once("Unknown flags (%u) in %s ABI structure", test_flags, str); + return true; +} + static int rseq_need_restart(struct task_struct *t, u32 cs_flags) { u32 flags, event_mask; int ret; - if (WARN_ON_ONCE(cs_flags & RSEQ_CS_NO_RESTART_FLAGS) || cs_flags) + if (rseq_warn_flags("rseq_cs", cs_flags)) return -EINVAL; /* Get thread flags. */ @@ -184,7 +199,7 @@ static int rseq_need_restart(struct task if (ret) return ret; - if (WARN_ON_ONCE(flags & RSEQ_CS_NO_RESTART_FLAGS) || flags) + if (rseq_warn_flags("rseq", flags)) return -EINVAL; /*