diff options
| author | Antonino A. Daplas <adaplas@gmail.com> | 2007-05-08 11:40:06 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-05-08 22:15:33 +0400 |
| commit | 2ae854777592856ad8ce4d4cdb6114804e2e28f6 (patch) | |
| tree | 49192562a7cbe6216442c6b3f3bee644f9a7091f /drivers/video | |
| parent | 32dd38030b3b4ca0aa18a5402059de27bf69ed6b (diff) | |
| download | linux-2ae854777592856ad8ce4d4cdb6114804e2e28f6.tar.xz | |
vgacon: disallow console operations when in KD_GRAPHICS mode
Reported by James Pearson as:
boot to run level 3
if not root, then make sure /dev/console is writeable
login and type:
setterm -blank 0
start X
type into an xterm:
while true; do echo "" > /dev/console; usleep 100000; done
while the above loop is running switch to the text console and back
again (Ctrl-Alt-F1 then Ctrl-Alt-F7)
... and the screen will be shifting (and wrapping) to the left.
This problem stems from continuously writing text to the system console (which
is in KD_TEXT mode) while the foreground console is in KD_GRAPHICS
mode. Somewhere along the way, console printing got confused and omitted the
KD_GRAPHICS/KD_TEXT test. Thus, vgacon attempted to scroll the screen of X,
which causes X to shift.
Fix by disallowing vgacon to touch the hardware when the vc is in KD_GRAPHICS
mode. A definitive fix entails a full audit of the console code.
Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/video')
| -rw-r--r-- | drivers/video/console/vgacon.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c index d0d2733ef479..2460b82a1d93 100644 --- a/drivers/video/console/vgacon.c +++ b/drivers/video/console/vgacon.c @@ -660,6 +660,9 @@ static void vgacon_set_cursor_size(int xpos, int from, int to) static void vgacon_cursor(struct vc_data *c, int mode) { + if (c->vc_mode != KD_TEXT) + return; + vgacon_restore_screen(c); switch (mode) { @@ -1318,7 +1321,7 @@ static int vgacon_scroll(struct vc_data *c, int t, int b, int dir, unsigned long oldo; unsigned int delta; - if (t || b != c->vc_rows || vga_is_gfx) + if (t || b != c->vc_rows || vga_is_gfx || c->vc_mode != KD_TEXT) return 0; if (!vga_hardscroll_enabled || lines >= c->vc_rows / 2) |