[PATCH 5.4 16/17] media: staging/intel-ipu3: css: Fix wrong size comparison imgu_css_fw_init

From: Greg Kroah-Hartman
Date: Wed Nov 10 2021 - 13:51:13 EST


From: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>

commit a44f9d6f9dc1fb314a3f1ed2dcd4fbbcc3d9f892 upstream.

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.

Turn binary_header into a flexible-array member[1][2], use the
struct_size() helper and fix the wrong size comparison. Notice
that the loaded firmware needs to contain at least one 'struct
imgu_fw_info' item in the binary_header[] array.

It's also worth mentioning that

"css->fw->size < struct_size(css->fwp, binary_header, 1)"

with binary_header declared as a flexible-array member is equivalent
to

"css->fw->size < sizeof(struct imgu_fw_header)"

with binary_header declared as a one-element array (as in the original
code).

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

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.10/process/deprecated.html#zero-length-and-one-element-arrays

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@xxxxxxxxxxxxxxx
Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/staging/media/ipu3/ipu3-css-fw.c | 7 +++----
drivers/staging/media/ipu3/ipu3-css-fw.h | 2 +-
2 files changed, 4 insertions(+), 5 deletions(-)

--- a/drivers/staging/media/ipu3/ipu3-css-fw.c
+++ b/drivers/staging/media/ipu3/ipu3-css-fw.c
@@ -124,12 +124,11 @@ int imgu_css_fw_init(struct imgu_css *cs
/* 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 < struct_size(css->fwp, binary_header, 1) ||
css->fwp->file_header.h_size != sizeof(struct imgu_fw_bi_file_h))
goto bad_fw;
- if (sizeof(struct imgu_fw_bi_file_h) +
- css->fwp->file_header.binary_nr * sizeof(struct imgu_fw_info) >
- css->fw->size)
+ if (struct_size(css->fwp, binary_header,
+ css->fwp->file_header.binary_nr) > css->fw->size)
goto bad_fw;

dev_info(dev, "loaded firmware version %.64s, %u binaries, %zu bytes\n",
--- a/drivers/staging/media/ipu3/ipu3-css-fw.h
+++ b/drivers/staging/media/ipu3/ipu3-css-fw.h
@@ -170,7 +170,7 @@ 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 *******************/