From: Jani Nikula jani.nikula@intel.com
[ Upstream commit 5bacecc3c56131c31f18b23d366f2184328fd9cf ]
Add a helper to get a pointer to struct displayid_header. To be pedantic, add buffer overflow checks to not touch the base if that itself would overflow.
Cc: Iaroslav Boliukin iam@lach.pw Cc: Dmitry Osipenko dmitry.osipenko@collabora.com Signed-off-by: Jani Nikula jani.nikula@intel.com Tested-by: Dmitry Osipenko dmitry.osipenko@collabora.com Reviewed-by: Dmitry Osipenko dmitry.osipenko@collabora.com Signed-off-by: Dmitry Osipenko dmitry.osipenko@collabora.com Link: https://patchwork.freedesktop.org/patch/msgid/4a03b3a5132642d3cdb6d4c2641422... Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/drm_displayid.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_displayid.c b/drivers/gpu/drm/drm_displayid.c index 32da557b960fd..82b7f0bb44097 100644 --- a/drivers/gpu/drm/drm_displayid.c +++ b/drivers/gpu/drm/drm_displayid.c @@ -7,13 +7,28 @@ #include <drm/drm_edid.h> #include <drm/drm_print.h>
+static const struct displayid_header * +displayid_get_header(const u8 *displayid, int length, int index) +{ + const struct displayid_header *base; + + if (sizeof(*base) > length - index) + return ERR_PTR(-EINVAL); + + base = (const struct displayid_header *)&displayid[index]; + + return base; +} + static int validate_displayid(const u8 *displayid, int length, int idx) { int i, dispid_length; u8 csum = 0; const struct displayid_header *base;
- base = (const struct displayid_header *)&displayid[idx]; + base = displayid_get_header(displayid, length, idx); + if (IS_ERR(base)) + return PTR_ERR(base);
DRM_DEBUG_KMS("base revision 0x%x, length %d, %d %d\n", base->rev, base->bytes, base->prod_id, base->ext_count);