From patchwork Sun Oct 18 19:20:07 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sasha Levin X-Patchwork-Id: 293232 From: Sasha Levin Date: Sun, 18 Oct 2020 19:20:07 +0000 Subject: [PATCH AUTOSEL 5.8 082/101] fbmem: add margin check to fb_check_caps() Message-Id: <20201018192026.4053674-82-sashal@kernel.org> List-Id: References: <20201018192026.4053674-1-sashal@kernel.org> In-Reply-To: <20201018192026.4053674-1-sashal@kernel.org> MIME-Version: 1.0 To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: George Kennedy , syzbot+e5fd3e65515b48c02a30@syzkaller.appspotmail.com, Dan Carpenter , Dhaval Giani , Bartlomiej Zolnierkiewicz , Sasha Levin , linux-fbdev@vger.kernel.org From: George Kennedy [ 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 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: Sasha Levin --- 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 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)