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 B1E1D1F5FA; Thu, 11 Apr 2024 10:09:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712830172; cv=none; b=fLfXjxRCaJ5w25yjtbLGUqxGvADLqSygC7wzb6spmhdfJDJiHKC0w0hSNoOgefkoxK5BBcawqyv1i7RyG8pgz+lWGMPHYEXJHi8FJcG21ymKQs47KTOcloH1igS+y/kYB5V8kQdFu8l93Igdtz5yg2anHG0Gfw4RPA2uriWnVqk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712830172; c=relaxed/simple; bh=jkAcQj2Xzf9uAAck7DojzTNaYxL0MHHUi6mA1xg72Ls=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BrM8FS02fdxIpCgdv4fQ9ICkz4c9gQa6a+ZHHjGzuxz0eJr4TSUzvIalyQuA3j3lnBtVVcUvIyecuA83Mh6StXwp73vhR2aIB3UFrW0lFLcZsxa34xa6TMZuZz6uwQx7uFk2ODu4iJ4e+h4+yZLhBEHqBRrwrujF5Tmw4FNlFHg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=JD2o91ed; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="JD2o91ed" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 36A84C43390; Thu, 11 Apr 2024 10:09:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1712830172; bh=jkAcQj2Xzf9uAAck7DojzTNaYxL0MHHUi6mA1xg72Ls=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JD2o91edXNe86rvw1wqIBY0/sFjnhKlT/f2WKJ+5XLTBrV/HoZNyQCeAoTlOknSwR pFkpeysK6XpYGdnuKwX9W4jPRlxr1C1iZdS+nZvJ4yt4CcWZKTSGF3MSQ7/DAeUgyz CqBCZqt1N3Loczw/izUJivO0aF6AElAvsOCwdRds= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzkaller , Vegard Nossum , "Gustavo A. R. Silva" , Harshit Mogalapalli , Kees Cook , Dan Carpenter , Sasha Levin Subject: [PATCH 6.8 010/143] VMCI: Fix memcpy() run-time warning in dg_dispatch_as_host() Date: Thu, 11 Apr 2024 11:54:38 +0200 Message-ID: <20240411095421.219713436@linuxfoundation.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240411095420.903937140@linuxfoundation.org> References: <20240411095420.903937140@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: Harshit Mogalapalli [ Upstream commit 19b070fefd0d024af3daa7329cbc0d00de5302ec ] Syzkaller hit 'WARNING in dg_dispatch_as_host' bug. memcpy: detected field-spanning write (size 56) of single field "&dg_info->msg" at drivers/misc/vmw_vmci/vmci_datagram.c:237 (size 24) WARNING: CPU: 0 PID: 1555 at drivers/misc/vmw_vmci/vmci_datagram.c:237 dg_dispatch_as_host+0x88e/0xa60 drivers/misc/vmw_vmci/vmci_datagram.c:237 Some code commentry, based on my understanding: 544 #define VMCI_DG_SIZE(_dg) (VMCI_DG_HEADERSIZE + (size_t)(_dg)->payload_size) /// This is 24 + payload_size memcpy(&dg_info->msg, dg, dg_size); Destination = dg_info->msg ---> this is a 24 byte structure(struct vmci_datagram) Source = dg --> this is a 24 byte structure (struct vmci_datagram) Size = dg_size = 24 + payload_size {payload_size = 56-24 =32} -- Syzkaller managed to set payload_size to 32. 35 struct delayed_datagram_info { 36 struct datagram_entry *entry; 37 struct work_struct work; 38 bool in_dg_host_queue; 39 /* msg and msg_payload must be together. */ 40 struct vmci_datagram msg; 41 u8 msg_payload[]; 42 }; So those extra bytes of payload are copied into msg_payload[], a run time warning is seen while fuzzing with Syzkaller. One possible way to fix the warning is to split the memcpy() into two parts -- one -- direct assignment of msg and second taking care of payload. Gustavo quoted: "Under FORTIFY_SOURCE we should not copy data across multiple members in a structure." Reported-by: syzkaller Suggested-by: Vegard Nossum Suggested-by: Gustavo A. R. Silva Signed-off-by: Harshit Mogalapalli Reviewed-by: Gustavo A. R. Silva Reviewed-by: Kees Cook Reviewed-by: Dan Carpenter Link: https://lore.kernel.org/r/20240105164001.2129796-2-harshit.m.mogalapalli@oracle.com Signed-off-by: Kees Cook Signed-off-by: Sasha Levin --- drivers/misc/vmw_vmci/vmci_datagram.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/misc/vmw_vmci/vmci_datagram.c b/drivers/misc/vmw_vmci/vmci_datagram.c index f50d22882476f..d1d8224c8800c 100644 --- a/drivers/misc/vmw_vmci/vmci_datagram.c +++ b/drivers/misc/vmw_vmci/vmci_datagram.c @@ -234,7 +234,8 @@ static int dg_dispatch_as_host(u32 context_id, struct vmci_datagram *dg) dg_info->in_dg_host_queue = true; dg_info->entry = dst_entry; - memcpy(&dg_info->msg, dg, dg_size); + dg_info->msg = *dg; + memcpy(&dg_info->msg_payload, dg + 1, dg->payload_size); INIT_WORK(&dg_info->work, dg_delayed_dispatch); schedule_work(&dg_info->work); -- 2.43.0