cdrom: fix improper type cast, which can leat to information leak (CVE-2018-18710)

debian/changelog

@@ -443,6 +443,8 @@ linux (4.18.14-1) UNRELEASED; urgency=medium
   * [x86] swiotlb: Enable swiotlb for > 4GiG RAM on 32-bit kernels
     (Closes: #908924)
   * mremap: properly flush TLB before releasing the page (CVE-2018-18281)
+  * cdrom: fix improper type cast, which can leat to information leak
+    (CVE-2018-18710)
 
  -- Ben Hutchings <ben@decadent.org.uk>  Mon, 08 Oct 2018 19:02:53 +0100
 

debian/patches/bugfix/all/cdrom-fix-improper-type-cast-which-can-leat-to-infor.patch

@@ -0,0 +1,34 @@
+From: Young_X <YangX92@hotmail.com>
+Date: Wed, 3 Oct 2018 12:54:29 +0000
+Subject: cdrom: fix improper type cast, which can leat to information leak.
+Origin: https://git.kernel.org/linus/e4f3aa2e1e67bb48dfbaaf1cad59013d5a5bc276
+Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2018-18710
+
+There is another cast from unsigned long to int which causes
+a bounds check to fail with specially crafted input. The value is
+then used as an index in the slot array in cdrom_slot_status().
+
+This issue is similar to CVE-2018-16658 and CVE-2018-10940.
+
+Signed-off-by: Young_X <YangX92@hotmail.com>
+Signed-off-by: Jens Axboe <axboe@kernel.dk>
+---
+ drivers/cdrom/cdrom.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
+index a5d5a96479bf..10802d1fc554 100644
+--- a/drivers/cdrom/cdrom.c
++++ b/drivers/cdrom/cdrom.c
+@@ -2445,7 +2445,7 @@ static int cdrom_ioctl_select_disc(struct cdrom_device_info *cdi,
+ 		return -ENOSYS;
+ 
+ 	if (arg != CDSL_CURRENT && arg != CDSL_NONE) {
+-		if ((int)arg >= cdi->capacity)
++		if (arg >= cdi->capacity)
+ 			return -EINVAL;
+ 	}
+ 
+-- 
+2.11.0
+

debian/patches/series

@@ -146,6 +146,7 @@ features/all/lockdown/arm64-add-kernel-config-option-to-lock-down-when.patch
 debian/i386-686-pae-pci-set-pci-nobios-by-default.patch
 bugfix/all/Revert-net-increase-fragment-memory-usage-limits.patch
 bugfix/all/mremap-properly-flush-TLB-before-releasing-the-page.patch
+bugfix/all/cdrom-fix-improper-type-cast-which-can-leat-to-infor.patch
 
 # Fix exported symbol versions
 bugfix/all/module-disable-matching-missing-version-crc.patch