[v5,0/4] fbcon: Fixes for screen resolution changes

Message

Helge Deller June 26, 2022, 8:56 a.m. UTC

This series fixes possible out-of-bound memory accesses when users trigger
screen resolutions changes with invalid input parameters, e.g. reconfigures
screen which is smaller than the current font size, or if the virtual screen
size is smaller than the physical screen size.

Major change in this version v5 is that since we can't easily push
commit 409d6c95f9c6 ("fbcon: Introduce wrapper for console->fb_info lookup")
downwards, a new patch #4 to clean up the old usage of "registered_fb[con2fb_map[i]]"
afterwards has been added.

v5:
- swapped patch #2 and #3
- modified patch #3 to use registered_fb[con2fb_map[i]] instead of
  fbcon_info_from_console(). This is necessary that the patch can
  be cleanly pushed back to v5.4
- added cleanup patch #4 to fix up patch #3 again to use fbcon_info_from_console()
  for v5.19+

v4:
- merged former patch #2 and #3
- added more Reviewed-by
- new patch #2 needs more testing. Note added to comit message that
  another patch needs to be backport as well.

Helge Deller (4):
  fbcon: Disallow setting font bigger than screen size
  fbmem: Prevent invalid virtual screen sizes
  fbcon: Prevent that screen size is smaller than font size
  fbcon: Use fbcon_info_from_console() in fbcon_modechange_possible()

 drivers/video/fbdev/core/fbcon.c | 32 ++++++++++++++++++++++++++++++++
 drivers/video/fbdev/core/fbmem.c | 10 +++++++++-
 include/linux/fbcon.h            |  4 ++++
 3 files changed, 45 insertions(+), 1 deletion(-)

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2.35.3