[PATCH 7.1 389/744] drm/sysfb: Return errno code from drm_sysfb_get_visible_size()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

7.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Zimmermann <tzimmermann@suse.de>

commit 7bab0f09d753f098977bbba3955d694c2e2c25da upstream.

Change the return type of drm_sysfb_get_visible_size() to s64 so
that it returns a possible errno code from _get_validated_size0().
Fix callers to handle the errno code.

The currently returned unsigned type converts an errno code to a
very large size value, which drivers interpret as visible size of
the system framebuffer. Later efforts to reserve the framebuffer
resource fail.

The bug has been present since efidrm and vesadrm got merged. It
was then part of each driver.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: 32ae90c66fb6 ("drm/sysfb: Add efidrm for EFI displays")
Fixes: a84eb6abe2b6 ("drm/sysfb: Add vesadrm for VESA displays")
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v6.16+
Link: https://patch.msgid.link/20260618084327.46567-4-tzimmermann@suse.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/gpu/drm/sysfb/drm_sysfb_helper.h      |    2 +-
 drivers/gpu/drm/sysfb/drm_sysfb_screen_info.c |    2 +-
 drivers/gpu/drm/sysfb/efidrm.c                |    7 ++++---
 drivers/gpu/drm/sysfb/vesadrm.c               |    6 +++---
 4 files changed, 9 insertions(+), 8 deletions(-)

--- a/drivers/gpu/drm/sysfb/drm_sysfb_helper.h
+++ b/drivers/gpu/drm/sysfb/drm_sysfb_helper.h
@@ -50,7 +50,7 @@ struct resource *drm_sysfb_get_memory_si
 int drm_sysfb_get_stride_si(struct drm_device *dev, const struct screen_info *si,
 			    const struct drm_format_info *format,
 			    unsigned int width, unsigned int height, u64 size);
-u64 drm_sysfb_get_visible_size_si(struct drm_device *dev, const struct screen_info *si,
+s64 drm_sysfb_get_visible_size_si(struct drm_device *dev, const struct screen_info *si,
 				  unsigned int height, unsigned int stride, u64 size);
 #endif
 
--- a/drivers/gpu/drm/sysfb/drm_sysfb_screen_info.c
+++ b/drivers/gpu/drm/sysfb/drm_sysfb_screen_info.c
@@ -71,7 +71,7 @@ int drm_sysfb_get_stride_si(struct drm_d
 }
 EXPORT_SYMBOL(drm_sysfb_get_stride_si);
 
-u64 drm_sysfb_get_visible_size_si(struct drm_device *dev, const struct screen_info *si,
+s64 drm_sysfb_get_visible_size_si(struct drm_device *dev, const struct screen_info *si,
 				  unsigned int height, unsigned int stride, u64 size)
 {
 	u64 vsize = mul_u32_u32(height, stride);
--- a/drivers/gpu/drm/sysfb/efidrm.c
+++ b/drivers/gpu/drm/sysfb/efidrm.c
@@ -150,7 +150,8 @@ static struct efidrm_device *efidrm_devi
 	const struct screen_info *si;
 	const struct drm_format_info *format;
 	int width, height, stride;
-	u64 vsize, mem_flags;
+	s64 vsize;
+	u64 mem_flags;
 	struct resource resbuf;
 	struct resource *res;
 	struct efidrm_device *efi;
@@ -204,8 +205,8 @@ static struct efidrm_device *efidrm_devi
 	if (stride < 0)
 		return ERR_PTR(stride);
 	vsize = drm_sysfb_get_visible_size_si(dev, si, height, stride, resource_size(res));
-	if (!vsize)
-		return ERR_PTR(-EINVAL);
+	if (vsize < 0)
+		return ERR_PTR(vsize);
 
 	drm_dbg(dev, "framebuffer format=%p4cc, size=%dx%d, stride=%d bytes\n",
 		&format->format, width, height, stride);
--- a/drivers/gpu/drm/sysfb/vesadrm.c
+++ b/drivers/gpu/drm/sysfb/vesadrm.c
@@ -400,7 +400,7 @@ static struct vesadrm_device *vesadrm_de
 	const struct screen_info *si;
 	const struct drm_format_info *format;
 	int width, height, stride;
-	u64 vsize;
+	s64 vsize;
 	struct resource resbuf;
 	struct resource *res;
 	struct vesadrm_device *vesa;
@@ -455,8 +455,8 @@ static struct vesadrm_device *vesadrm_de
 	if (stride < 0)
 		return ERR_PTR(stride);
 	vsize = drm_sysfb_get_visible_size_si(dev, si, height, stride, resource_size(res));
-	if (!vsize)
-		return ERR_PTR(-EINVAL);
+	if (vsize < 0)
+		return ERR_PTR(vsize);
 
 	drm_dbg(dev, "framebuffer format=%p4cc, size=%dx%d, stride=%d bytes\n",
 		&format->format, width, height, stride);