From: George Kennedy Date: Tue, 7 Jul 2020 19:26:03 +0000 (-0400) Subject: fbmem: add margin check to fb_check_caps() X-Git-Tag: v4.4.283~2 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=15af9988ab754f7221281d6c9022e0193006c2aa;p=thirdparty%2Fkernel%2Fstable.git 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: George Kennedy Reported-by: syzbot+e5fd3e65515b48c02a30@syzkaller.appspotmail.com Reviewed-by: Dan Carpenter Cc: Dhaval Giani Signed-off-by: Bartlomiej Zolnierkiewicz Link: https://patchwork.freedesktop.org/patch/msgid/1594149963-13801-1-git-send-email-george.kennedy@oracle.com Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index 348be7368f490..afb84c27110d8 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -1001,6 +1001,10 @@ 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)