On 5/9/25 22:06, Kees Cook wrote:
It looks like attempting to write to the "store_modes" sysfs node will run afoul of unregistered consoles:UBSAN: array-index-out-of-bounds in drivers/video/fbdev/core/fbcon.c:122:28 index -1 is out of range for type 'fb_info *[32]' ... fbcon_info_from_console+0x192/0x1a0 drivers/video/fbdev/core/fbcon.c:122 fbcon_new_modelist+0xbf/0x2d0 drivers/video/fbdev/core/fbcon.c:3048 fb_new_modelist+0x328/0x440 drivers/video/fbdev/core/fbmem.c:673 store_modes+0x1c9/0x3e0 drivers/video/fbdev/core/fbsysfs.c:113 dev_attr_store+0x55/0x80 drivers/base/core.c:2439 static struct fb_info *fbcon_registered_fb[FB_MAX]; ... static signed char con2fb_map[MAX_NR_CONSOLES]; ... static struct fb_info *fbcon_info_from_console(int console) ... return fbcon_registered_fb[con2fb_map[console]]; If con2fb_map contains a -1 things go wrong here. Instead, return NULL, as callers of fbcon_info_from_console() are trying to compare against existing "info" pointers, so error handling should kick in correctly. Reported-by: syzbot+a7d4444e7b6e74357...@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/679d0a8f.050a0220.163cdc.000c....@google.com/ Signed-off-by: Kees Cook <k...@kernel.org> --- drivers/video/fbdev/core/fbcon.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
applied to fbdev for-next git tree. Thanks! Helge
