Commit a49145ac authored by George Kennedy's avatar George Kennedy Committed by Bartlomiej Zolnierkiewicz

fbmem: add margin check to fb_check_caps()

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: 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
parent 54d04ea8
...@@ -1006,6 +1006,10 @@ fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var) ...@@ -1006,6 +1006,10 @@ fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var)
return 0; 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); ret = info->fbops->fb_check_var(var, info);
if (ret) if (ret)
......
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