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Commit 6be10fb6 authored by George Kennedy's avatar George Kennedy Committed by Greg Kroah-Hartman
Browse files

fbmem: add margin check to fb_check_caps() 



commit a49145acfb975d921464b84fe00279f99827d816 upstream.

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: default avatarGeorge Kennedy <george.kennedy@oracle.com>
Reported-by: default avatar <syzbot+e5fd3e65515b48c02a30@syzkaller.appspotmail.com>
Reviewed-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Cc: Dhaval Giani <dhaval.giani@oracle.com>
Signed-off-by: default avatarBartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1594149963-13801-1-git-send-email-george.kennedy@oracle.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0776c1a2

drivers/video/fbdev/core/fbmem.c

+4 −0
Original line number Diff line number Diff line
@@ -991,6 +991,10 @@ fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var) 
			goto done;

		}



		/* 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)