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| author | Kees Cook <kees@kernel.org> | 2025-05-09 23:06:47 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-06-27 13:08:57 +0300 |
| commit | 519ba75728ee8cd561dce25fc52a2ec5c47171dc (patch) | |
| tree | f343218f7f95ba9cef00d6f4e69aed11846bc5ed /drivers/video/fbdev | |
| parent | 8df53ee74cac0cd1ed8357df6e84538a54b87bd6 (diff) | |
| download | linux-519ba75728ee8cd561dce25fc52a2ec5c47171dc.tar.xz | |
fbcon: Make sure modelist not set on unregistered console
[ 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>
Diffstat (limited to 'drivers/video/fbdev')
| -rw-r--r-- | drivers/video/fbdev/core/fbcon.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c index 7a6f9a3cb3ba..75996ef9992e 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; |