This is a note to let you know that I've just added the patch titled fbmem: add margin check to fb_check_caps() to the 5.8-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: fbmem-add-margin-check-to-fb_check_caps.patch and it can be found in the queue-5.8 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 76ef00cb6bfdd6e4f1219ba5fe2979275a5de90d Author: George Kennedy <george.kennedy@xxxxxxxxxx> Date: Tue Jul 7 15:26:03 2020 -0400 fbmem: add margin check to fb_check_caps() [ 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@xxxxxxxxxx> Reported-by: syzbot+e5fd3e65515b48c02a30@xxxxxxxxxxxxxxxxxxxxxxxxx Reviewed-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Cc: Dhaval Giani <dhaval.giani@xxxxxxxxxx> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx> Link: https://patchwork.freedesktop.org/patch/msgid/1594149963-13801-1-git-send-email-george.kennedy@xxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index da7c88ffaa6a8..1136b569ccb7c 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)