From mboxrd@z Thu Jan 1 00:00:00 1970 From: George Kennedy Date: Tue, 07 Jul 2020 19:26:03 +0000 Subject: [PATCH 1/1] fbmem: add margin check to fb_check_caps() Message-Id: <1594149963-13801-1-git-send-email-george.kennedy@oracle.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-fbdev@vger.kernel.org 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 Suggested-by: Dan Carpenter Reported-by: syzbot+e5fd3e65515b48c02a30@syzkaller.appspotmail.com --- 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 30e73ec..cd50302 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -1007,6 +1007,10 @@ static int fb_check_caps(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) -- 1.8.3.1