fbdevhw: Refuse to touch PCI devices on the fallback probe path

Fixes: xorg/driver/xf86-video-fbdev#9


Signed-off-by: Adam Jackson <ajax@redhat.com>
(cherry picked from commit fc78bcca)

hw/xfree86/fbdevhw/fbdevhw.c

@@ -329,6 +329,22 @@ fbdev_open(int scrnIndex, const char *dev, char **namep)
         return -1;
     }
 
+    /* only touch non-PCI devices on this path */
+    {
+        char buf[PATH_MAX];
+        char *sysfs_path = NULL;
+        char *node = strrchr(dev, '/') + 1;
+
+        if (asprintf(&sysfs_path, "/sys/class/graphics/%s", node) < 0 ||
+            readlink(sysfs_path, buf, sizeof(buf) < 0) ||
+            strstr(buf, "devices/pci")) {
+            free(sysfs_path);
+            close(fd);
+            return -1;
+        }
+        free(sysfs_path);
+    }
+
     if (namep) {
         if (-1 == ioctl(fd, FBIOGET_FSCREENINFO, (void *) (&fix))) {
             *namep = NULL;

[Christian Schaubschläger]

Hello, this commit breaks things for me for some reason:

(II) FBDEV: driver for framebuffer: fbdev
(II) Loading sub module "fbdevhw"
(II) LoadModule: "fbdevhw"
(II) Loading /usr/X11/lib/xorg/modules/libfbdevhw.so
(II) Module fbdevhw: vendor="X.Org Foundation"
        compiled for 1.20.2, module version = 0.0.2
        ABI class: X.Org Video Driver, version 24.0
(EE) Unable to find a valid framebuffer device

On my system I don't have any /sys/bus/pci/devices/*/graphics* entries, but I do have a /dev/fb0:

-bash-4.4# ls /sys/bus/pci/devices/*/graphics*
ls: cannot access '/sys/bus/pci/devices/*/graphics*': No such file or directory

-bash-4.4# ls -l /dev/fb0                     
crw-rw---- 1 root video 29, 0 Oct 19 09:22 /dev/fb0

-bash-4.4# ls -l /sys/class/graphics/         
total 0
lrwxrwxrwx 1 root root 0 Oct 19 09:22 fb0 -> ../../devices/platform/vesa-framebuffer.0/graphics/fb0
lrwxrwxrwx 1 root root 0 Oct 19 09:22 fbcon -> ../../devices/virtual/graphics/fbcon

-bash-4.4# ls -l /sys/class/graphics/fb0/     
total 0
-rw-r--r-- 1 root root 4096 Oct 19 09:25 bits_per_pixel
-rw-r--r-- 1 root root 4096 Oct 19 09:25 bl_curve
-rw-r--r-- 1 root root 4096 Oct 19 09:25 blank
-rw-r--r-- 1 root root 4096 Oct 19 09:25 console
-rw-r--r-- 1 root root 4096 Oct 19 09:25 cursor
-r--r--r-- 1 root root 4096 Oct 19 09:25 dev
lrwxrwxrwx 1 root root    0 Oct 19 09:25 device -> ../../../vesa-framebuffer.0
-rw-r--r-- 1 root root 4096 Oct 19 09:25 mode
-rw-r--r-- 1 root root 4096 Oct 19 09:25 modes
-r--r--r-- 1 root root 4096 Oct 19 09:25 name
-rw-r--r-- 1 root root 4096 Oct 19 09:25 pan
-rw-r--r-- 1 root root 4096 Oct 19 09:25 rotate
-rw-r--r-- 1 root root 4096 Oct 19 09:25 state
-r--r--r-- 1 root root 4096 Oct 19 09:25 stride
lrwxrwxrwx 1 root root    0 Oct 19 09:25 subsystem -> ../../../../../class/graphics
-rw-r--r-- 1 root root 4096 Oct 19 09:22 uevent
-rw-r--r-- 1 root root 4096 Oct 19 09:25 virtual_size

If you need more information just let me know!

Regards Christian

[Adam Jackson]

I don't understand why this patch would have that effect? We're not looking in /sys/bus/pci, we're looking in /sys/class/graphics.