diff options
| author | Thomas Zimmermann <tzimmermann@suse.de> | 2025-06-17 17:09:34 +0300 |
|---|---|---|
| committer | Thomas Zimmermann <tzimmermann@suse.de> | 2025-06-27 17:00:49 +0300 |
| commit | 615cc4223fcbe1e0e6f68b8494b26bb6c08d917a (patch) | |
| tree | 6cb91ec4b106cb7c965573839f5b9c90f5bd7a8e | |
| parent | f6faebc11a8a6d9521e5ab00481bd22ed9c7c67d (diff) | |
| download | linux-615cc4223fcbe1e0e6f68b8494b26bb6c08d917a.tar.xz | |
drm/vesadrm: Avoid NULL-ptr deref in vesadrm_pmi_cmap_write()
Only set PMI fields if the screen_info's Vesa PM segment has been
set. Vesa PMI is the power-management interface. It also provides
means to set the color palette. The interface is optional, so not
all VESA graphics cards support it. Print vesafb's warning [1] if
the hardware palette cannot be set at all.
If unsupported the field PrimaryPalette in struct vesadrm.pmi is
NULL, which results in a segmentation fault. Happens with qemu's
Cirrus emulation.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: 814d270b31d2 ("drm/sysfb: vesadrm: Add gamma correction")
Link: https://elixir.bootlin.com/linux/v6.15/source/drivers/video/fbdev/vesafb.c#L375 # 1
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Acked-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://lore.kernel.org/r/20250617140944.142392-1-tzimmermann@suse.de
| -rw-r--r-- | drivers/gpu/drm/sysfb/vesadrm.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/drivers/gpu/drm/sysfb/vesadrm.c b/drivers/gpu/drm/sysfb/vesadrm.c index 4d62c78e7d1e..f7532db3831f 100644 --- a/drivers/gpu/drm/sysfb/vesadrm.c +++ b/drivers/gpu/drm/sysfb/vesadrm.c @@ -362,14 +362,19 @@ static struct vesadrm_device *vesadrm_device_create(struct drm_driver *drv, if (!__screen_info_vbe_mode_nonvga(si)) { vesa->cmap_write = vesadrm_vga_cmap_write; -#if defined(CONFIG_X86_32) } else { +#if defined(CONFIG_X86_32) phys_addr_t pmi_base = __screen_info_vesapm_info_base(si); - const u16 *pmi_addr = phys_to_virt(pmi_base); - vesa->pmi.PrimaryPalette = (u8 *)pmi_addr + pmi_addr[2]; - vesa->cmap_write = vesadrm_pmi_cmap_write; + if (pmi_base) { + const u16 *pmi_addr = phys_to_virt(pmi_base); + + vesa->pmi.PrimaryPalette = (u8 *)pmi_addr + pmi_addr[2]; + vesa->cmap_write = vesadrm_pmi_cmap_write; + } else #endif + if (format->is_color_indexed) + drm_warn(dev, "hardware palette is unchangeable, colors may be incorrect\n"); } #ifdef CONFIG_X86 |