From: Kees Cook <kees@kernel.org> stable inclusion from stable-v6.6.95 commit 519ba75728ee8cd561dce25fc52a2ec5c47171dc category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/ICK4O9 CVE: CVE-2025-38198 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit cedc1b63394a866bf8663a3e40f4546f1d28c8d8 ] 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+a7d4444e7b6e743572f7@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/679d0a8f.050a0220.163cdc.000c.GAE@google.com/ Signed-off-by: Kees Cook <kees@kernel.org> Signed-off-by: Helge Deller <deller@gmx.de> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Yifan Qiao <qiaoyifan4@huawei.com> --- drivers/video/fbdev/core/fbcon.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c index 405d587450ef..b46719b95a8a 100644 --- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c @@ -115,9 +115,14 @@ static signed char con2fb_map_boot[MAX_NR_CONSOLES]; static struct fb_info *fbcon_info_from_console(int console) { + signed char fb; WARN_CONSOLE_UNLOCKED(); - return fbcon_registered_fb[con2fb_map[console]]; + fb = con2fb_map[console]; + if (fb < 0 || fb >= ARRAY_SIZE(fbcon_registered_fb)) + return NULL; + + return fbcon_registered_fb[fb]; } static int logo_lines; -- 2.39.2