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 DBB09142E94; Fri, 29 Mar 2024 12:35:26 +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=1711715726; cv=none; b=bFRqAAIyyMHpBZzc/mVGJSA7g2YbGOTULFiWvmemVaiXYtaeDuVpKEx1nCMT7EPyz2yerpiFvWEuDKYjP3RPa09FjUf9uMRAln6sFp4BMvMhf/CL2A4iC+cNomEdbcIxyd5mDcwmoR9uAbi395Y0NzkylF+a01Q8DyeiaFxB4pM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711715726; c=relaxed/simple; bh=eDX8oDgda9OYKH8SbjNNZLEdT2O+EKxz+JxtXv63BIk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=AvM8zJoajxHXR1sVL+2mW4MeWFaOxuOcOlq6zUhEBYONAa8ZfyHw2F7md/CWiJPNoteaHVa6sMarehVJ/yrhtmhIkzVMcG30zuRoJqRGOJ8n2EmKAv2r2V1jgw5FPzQJdNiekJxVbyI28nO219ahTZ4O1ahrq7oG95W5q40kZFo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=iPOVTpSi; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="iPOVTpSi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3610BC433F1; Fri, 29 Mar 2024 12:35:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1711715726; bh=eDX8oDgda9OYKH8SbjNNZLEdT2O+EKxz+JxtXv63BIk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iPOVTpSik2o5EjG75JMs9F3ulVQq1Hl4TCwcAqNMm7r4yy4wgl/HGrtyS/Dfu/399 Ao0uM7qrzBv87JldqUzxU72Fy+PQkYNSZoVMy+4K7cq6QkxBw6Wfue5zgfLse+8kSe U7sL6nKAIVtfAoNP5c0nX7/2LBlbZwqYmE+PDm0x0YYv44w57YyEY1ef0mzdfaepep JTF4TjlFnJviZD1YtbrWVzVcQGPNgBtJv//VALasmTldNnRfnuiXxIeLxjuU0jTevg OMkznUqFrHlUY6r9Va3s6xENJBkCXFxyUVi67Y3vfp8Opkfxb1Zi8QYBKkm5F/nzJw wXqoCl5gHH/aw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Harshit Mogalapalli , syzkaller , Vegard Nossum , "Gustavo A . R . Silva" , Kees Cook , Dan Carpenter , Sasha Levin , bryantan@vmware.com, vdasa@vmware.com, gregkh@linuxfoundation.org Subject: [PATCH AUTOSEL 4.19 03/11] VMCI: Fix memcpy() run-time warning in dg_dispatch_as_host() Date: Fri, 29 Mar 2024 08:35:09 -0400 Message-ID: <20240329123522.3086878-3-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240329123522.3086878-1-sashal@kernel.org> References: <20240329123522.3086878-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 4.19.311 Content-Transfer-Encoding: 8bit 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 8a4b6bbe1beed..275542e8b2ad9 100644 --- a/drivers/misc/vmw_vmci/vmci_datagram.c +++ b/drivers/misc/vmw_vmci/vmci_datagram.c @@ -242,7 +242,8 @@ 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