Hi
Am 02.04.25 um 15:16 schrieb Patrik Jakobsson:
On Tue, Apr 1, 2025 at 6:23 PM Thomas Zimmermann <tzimmerm...@suse.de> wrote:
There need to be least 5 bytes in the vendor descriptor. Return
an error otherwise. Also change the branching to early-out on
the error. Adjust indention of the rest of the parser function.
Signed-off-by: Thomas Zimmermann <tzimmerm...@suse.de>
---
drivers/gpu/drm/udl/udl_main.c | 72 +++++++++++++++++-----------------
1 file changed, 36 insertions(+), 36 deletions(-)
diff --git a/drivers/gpu/drm/udl/udl_main.c b/drivers/gpu/drm/udl/udl_main.c
index 4291ddb7158c4..58d6065589d3a 100644
--- a/drivers/gpu/drm/udl/udl_main.c
+++ b/drivers/gpu/drm/udl/udl_main.c
@@ -45,43 +45,43 @@ static int udl_parse_vendor_descriptor(struct udl_device
*udl)
goto unrecognized;
len = ret;
- if (len > 5) {
- DRM_INFO("vendor descriptor length: %u data:%11ph\n",
- len, desc);
-
- if ((desc[0] != len) || /* descriptor length */
- (desc[1] != 0x5f) || /* vendor descriptor type */
- (desc[2] != 0x01) || /* version (2 bytes) */
- (desc[3] != 0x00) ||
- (desc[4] != len - 2)) /* length after type */
- goto unrecognized;
-
- desc_end = desc + len;
- desc += 5; /* the fixed header we've already parsed */
-
- while (desc < desc_end) {
- u8 length;
- u16 key;
-
- key = le16_to_cpu(*((u16 *) desc));
- desc += sizeof(u16);
- length = *desc;
- desc++;
-
- switch (key) {
- case 0x0200: { /* max_area */
- u32 max_area;
- max_area = le32_to_cpu(*((u32 *)desc));
- DRM_DEBUG("DL chip limited to %d pixel modes\n",
- max_area);
- udl->sku_pixel_limit = max_area;
- break;
- }
- default:
- break;
- }
- desc += length;
+ if (len < 5)
Hi Thomas,
Shouldn't this be if (len <= 5)? The old code only parsed if the
descriptor returned at least 6 bytes.
Right, I also noticed that. But I though it was a mistake. The header is
5 bytes and if there are no key-value pairs it's still a valid
descriptor AFAICT. Patch 9 of the series sets a default for the pixel
limit and the adapter would be usable. I rather not change the new
logic, but add an explanation to the commit description. Ok?
Best regards
Thomas
-Patrik
+ goto unrecognized;
+
+ DRM_INFO("vendor descriptor length: %u data:%11ph\n", len, desc);
+
+ if ((desc[0] != len) || /* descriptor length */
+ (desc[1] != 0x5f) || /* vendor descriptor type */
+ (desc[2] != 0x01) || /* version (2 bytes) */
+ (desc[3] != 0x00) ||
+ (desc[4] != len - 2)) /* length after type */
+ goto unrecognized;
+
+ desc_end = desc + len;
+ desc += 5; /* the fixed header we've already parsed */
+
+ while (desc < desc_end) {
+ u8 length;
+ u16 key;
+
+ key = le16_to_cpu(*((u16 *)desc));
+ desc += sizeof(u16);
+ length = *desc;
+ desc++;
+
+ switch (key) {
+ case 0x0200: { /* max_area */
+ u32 max_area = le32_to_cpu(*((u32 *)desc));
+
+ DRM_DEBUG("DL chip limited to %d pixel modes\n",
+ max_area);
+ udl->sku_pixel_limit = max_area;
+ break;
+ }
+ default:
+ break;
}
+ desc += length;
}
goto success;
--
2.49.0
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
