linux-hardening - [PATCH v2 1/2] media: staging/intel-ipu3: css: Fix wrong size comparison

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Message-ID: <184d96f95d6261b1a91704eb68adbd0a2e1c2cc2.1627646101.git.gustavoars@kernel.org>
Date:   Fri, 30 Jul 2021 07:08:13 -0500
From:   "Gustavo A. R. Silva" <gustavoars@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     Yong Zhi <yong.zhi@...el.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Bingbu Cao <bingbu.cao@...el.com>,
        Tianshu Qiu <tian.shu.qiu@...el.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-media@...r.kernel.org, linux-staging@...ts.linux.dev,
        linux-hardening@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: [PATCH v2 1/2] media: staging/intel-ipu3: css: Fix wrong size
 comparison

There is a wrong comparison of the total size of the loaded firmware
css->fw->size with the size of a pointer to struct imgu_fw_header.

Fix this by using the right operand 'struct imgu_fw_header' for
sizeof, instead of 'struct imgu_fw_header *' and turn binary_header
into a flexible-array member. Also, adjust the relational operator
to be '<=' instead of '<', as it seems that the intention of the
comparison is to determine if the loaded firmware contains any
'struct imgu_fw_info' items in the binary_header[] array than merely
the file_header (struct imgu_fw_bi_file_h).

The replacement of the one-element array with a flexible-array member
also help with the ongoing efforts to globally enable -Warray-bounds
and get us closer to being able to tighten the FORTIFY_SOURCE routines
on memcpy().

Link: https://github.com/KSPP/linux/issues/79
Link: https://github.com/KSPP/linux/issues/109
Fixes: 09d290f0ba21 ("media: staging/intel-ipu3: css: Add support for firmware management")
Cc: stable@...r.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
---

It'd be just great if someone that knows this code better can confirm
these changes are correct. In particular the adjustment of the
relational operator. Thanks!

Changes in v2:
 - Use flexible array and adjust relational operator, accordingly.
 - Update changelog text.

 drivers/staging/media/ipu3/ipu3-css-fw.c | 2 +-
 drivers/staging/media/ipu3/ipu3-css-fw.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/media/ipu3/ipu3-css-fw.c b/drivers/staging/media/ipu3/ipu3-css-fw.c
index 45aff76198e2..630cb5186b48 100644
--- a/drivers/staging/media/ipu3/ipu3-css-fw.c
+++ b/drivers/staging/media/ipu3/ipu3-css-fw.c
@@ -124,7 +124,7 @@ int imgu_css_fw_init(struct imgu_css *css)
 	/* Check and display fw header info */
 
 	css->fwp = (struct imgu_fw_header *)css->fw->data;
-	if (css->fw->size < sizeof(struct imgu_fw_header *) ||
+	if (css->fw->size <= sizeof(struct imgu_fw_header) ||
 	    css->fwp->file_header.h_size != sizeof(struct imgu_fw_bi_file_h))
 		goto bad_fw;
 	if (sizeof(struct imgu_fw_bi_file_h) +
diff --git a/drivers/staging/media/ipu3/ipu3-css-fw.h b/drivers/staging/media/ipu3/ipu3-css-fw.h
index 3c078f15a295..c0bc57fd678a 100644
--- a/drivers/staging/media/ipu3/ipu3-css-fw.h
+++ b/drivers/staging/media/ipu3/ipu3-css-fw.h
@@ -171,7 +171,7 @@ struct imgu_fw_bi_file_h {
 
 struct imgu_fw_header {
 	struct imgu_fw_bi_file_h file_header;
-	struct imgu_fw_info binary_header[1];	/* binary_nr items */
+	struct imgu_fw_info binary_header[];	/* binary_nr items */
 };
 
 /******************* Firmware functions *******************/
-- 
2.27.0