From: George Kennedy george.kennedy@oracle.com
[ Upstream commit a49145acfb975d921464b84fe00279f99827d816 ]
A fb_ioctl() FBIOPUT_VSCREENINFO call with invalid xres setting or yres setting in struct fb_var_screeninfo will result in a KASAN: vmalloc-out-of-bounds failure in bitfill_aligned() as the margins are being cleared. The margins are cleared in chunks and if the xres setting or yres setting is a value of zero upto the chunk size, the failure will occur.
Add a margin check to validate xres and yres settings.
Signed-off-by: George Kennedy george.kennedy@oracle.com Reported-by: syzbot+e5fd3e65515b48c02a30@syzkaller.appspotmail.com Reviewed-by: Dan Carpenter dan.carpenter@oracle.com Cc: Dhaval Giani dhaval.giani@oracle.com Signed-off-by: Bartlomiej Zolnierkiewicz b.zolnierkie@samsung.com Link: https://patchwork.freedesktop.org/patch/msgid/1594149963-13801-1-git-send-em... Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/video/fbdev/core/fbmem.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index 6815bfb7f5724..e33bf1c386926 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -1006,6 +1006,10 @@ fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var) return 0; }
+ /* bitfill_aligned() assumes that it's at least 8x8 */ + if (var->xres < 8 || var->yres < 8) + return -EINVAL; + ret = info->fbops->fb_check_var(var, info);
if (ret)