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 2EFE19446 for ; Sun, 13 Aug 2023 21:42:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AA56DC433C8; Sun, 13 Aug 2023 21:42:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1691962931; bh=5KgzM63Zrgw//2hLiYqcGjmF8S8om+CJgGSZ2PtFpSo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Pz8lR12JVj9GEuuVLzPehUmKkyui2CRLKIfpfeAWS/YZpUzpTaFja29QZSlJmsSHu EofiHsvM7qNzfadukMUbwegeCHCYqklGrke82MELci+eppAqqg5RfgnHa7yODZuoVS Z9DCW5cWoeIsXTHxn5JbxX6FOlEhuSfuDYS0mOgM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Christophe JAILLET , Alan Stern , syzbot+e7d46eb426883fb97efd@syzkaller.appspotmail.com Subject: [PATCH 5.10 22/68] usb-storage: alauda: Fix uninit-value in alauda_check_media() Date: Sun, 13 Aug 2023 23:19:23 +0200 Message-ID: <20230813211708.828534758@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230813211708.149630011@linuxfoundation.org> References: <20230813211708.149630011@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: Alan Stern commit a6ff6e7a9dd69364547751db0f626a10a6d628d2 upstream. Syzbot got KMSAN to complain about access to an uninitialized value in the alauda subdriver of usb-storage: BUG: KMSAN: uninit-value in alauda_transport+0x462/0x57f0 drivers/usb/storage/alauda.c:1137 CPU: 0 PID: 12279 Comm: usb-storage Not tainted 5.3.0-rc7+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x191/0x1f0 lib/dump_stack.c:113 kmsan_report+0x13a/0x2b0 mm/kmsan/kmsan_report.c:108 __msan_warning+0x73/0xe0 mm/kmsan/kmsan_instr.c:250 alauda_check_media+0x344/0x3310 drivers/usb/storage/alauda.c:460 The problem is that alauda_check_media() doesn't verify that its USB transfer succeeded before trying to use the received data. What should happen if the transfer fails isn't entirely clear, but a reasonably conservative approach is to pretend that no media is present. A similar problem exists in a usb_stor_dbg() call in alauda_get_media_status(). In this case, when an error occurs the call is redundant, because usb_stor_ctrl_transfer() already will print a debugging message. Finally, unrelated to the uninitialized memory access, is the fact that alauda_check_media() performs DMA to a buffer on the stack. Fortunately usb-storage provides a general purpose DMA-able buffer for uses like this. We'll use it instead. Reported-and-tested-by: syzbot+e7d46eb426883fb97efd@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/0000000000007d25ff059457342d@google.com/T/ Suggested-by: Christophe JAILLET Signed-off-by: Alan Stern Fixes: e80b0fade09e ("[PATCH] USB Storage: add alauda support") Cc: Link: https://lore.kernel.org/r/693d5d5e-f09b-42d0-8ed9-1f96cd30bcce@rowland.harvard.edu Signed-off-by: Greg Kroah-Hartman --- drivers/usb/storage/alauda.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) --- a/drivers/usb/storage/alauda.c +++ b/drivers/usb/storage/alauda.c @@ -318,7 +318,8 @@ static int alauda_get_media_status(struc rc = usb_stor_ctrl_transfer(us, us->recv_ctrl_pipe, command, 0xc0, 0, 1, data, 2); - usb_stor_dbg(us, "Media status %02X %02X\n", data[0], data[1]); + if (rc == USB_STOR_XFER_GOOD) + usb_stor_dbg(us, "Media status %02X %02X\n", data[0], data[1]); return rc; } @@ -454,9 +455,14 @@ static int alauda_init_media(struct us_d static int alauda_check_media(struct us_data *us) { struct alauda_info *info = (struct alauda_info *) us->extra; - unsigned char status[2]; + unsigned char *status = us->iobuf; + int rc; - alauda_get_media_status(us, status); + rc = alauda_get_media_status(us, status); + if (rc != USB_STOR_XFER_GOOD) { + status[0] = 0xF0; /* Pretend there's no media */ + status[1] = 0; + } /* Check for no media or door open */ if ((status[0] & 0x80) || ((status[0] & 0x1F) == 0x10)