9.3 - DSA-4497

Several vulnerabilities have been discovered in the Linux kernel that may lead to a privilege escalation, denial of service or information leaks.

CVE-2015-8553

Jan Beulich discovered that CVE-2015-2150 was not completely addressed. If a PCI physical function is passed through to a Xen guest, the guest is able to access its memory and I/O regions before enabling decoding of those regions. This could result in a denial-of-service (unexpected NMI) on the host.

The fix for this is incompatible with qemu versions before 2.5.

(CVE ID not yet assigned)

Denis Andzakovic reported a missing type check in the IPv4 multicast routing implementation. A user with the CAP_NET_ADMIN capability (in any user namespace) could use this for denial-of-service (memory corruption or crash) or possibly for privilege escalation.

CVE-2018-5995

ADLab of VenusTech discovered that the kernel logged the virtual addresses assigned to per-CPU data, which could make it easier to exploit other vulnerabilities.

CVE-2018-20836

chenxiang reported a race condition in libsas, the kernel subsystem supporting Serial Attached SCSI (SAS) devices, which could lead to a use-after-free. It is not clear how this might be exploited.

CVE-2018-20856

Xiao Jin reported a potential double-free in the block subsystem, in case an error occurs while initialising the I/O scheduler for a block device. It is not clear how this might be exploited.

CVE-2019-1125

It was discovered that most x86 processors could speculatively skip a conditional SWAPGS instruction used when entering the kernel from user mode, and/or could speculatively execute it when it should be skipped. This is a subtype of Spectre variant 1, which could allow local users to obtain sensitive information from the kernel or other processes. It has been mitigated by using memory barriers to limit speculative execution. Systems using an i386 kernel are not affected as the kernel does not use SWAPGS.

CVE-2019-3882

It was found that the vfio implementation did not limit the number of DMA mappings to device memory. A local user granted ownership of a vfio device could use this to cause a denial of service (out-of-memory condition).

CVE-2019-3900

It was discovered that vhost drivers did not properly control the amount of work done to service requests from guest VMs. A malicious guest could use this to cause a denial-of-service (unbounded CPU usage) on the host.

CVE-2019-10207

The syzkaller tool found a potential null dereference in various drivers for UART-attached Bluetooth adapters. A local user with access to a pty device or other suitable tty device could use this for denial-of-service (BUG/oops).

CVE-2019-10638

Amit Klein and Benny Pinkas discovered that the generation of IP packet IDs used a weak hash function, "jhash". This could enable tracking individual computers as they communicate with different remote servers and from different networks. The "siphash" function is now used instead.

CVE-2019-10639

Amit Klein and Benny Pinkas discovered that the generation of IP packet IDs used a weak hash function that incorporated a kernel virtual address. This hash function is no longer used for IP IDs, although it is still used for other purposes in the network stack.

CVE-2019-13631

It was discovered that the gtco driver for USB input tablets could overrun a stack buffer with constant data while parsing the device's descriptor. A physically present user with a specially constructed USB device could use this to cause a denial-of-service (BUG/oops), or possibly for privilege escalation.

CVE-2019-13648

Praveen Pandey reported that on PowerPC (ppc64el) systems without Transactional Memory (TM), the kernel would still attempt to restore TM state passed to the sigreturn() system call. A local user could use this for denial-of-service (oops).

CVE-2019-14283

The syzkaller tool found a missing bounds check in the floppy disk driver. A local user with access to a floppy disk device, with a disk present, could use this to read kernel memory beyond the I/O buffer, possibly obtaining sensitive information.

CVE-2019-14284

The syzkaller tool found a potential division-by-zero in the floppy disk driver. A local user with access to a floppy disk device could use this for denial-of-service (oops).

(CVE ID not yet assigned)

Denis Andzakovic reported a possible use-after-free in the TCP sockets implementation. A local user could use this for denial-of-service (memory corruption or crash) or possibly for privilege escalation.

(CVE ID not yet assigned)

The netfilter conntrack subsystem used kernel addresses as user-visible IDs, which could make it easier to exploit other security vulnerabilities.

XSA-300

Julien Grall reported that Linux does not limit the amount of memory which a domain will attempt to baloon out, nor limits the amount of "foreign / grant map" memory which any individual guest can consume, leading to denial of service conditions (for host or guests).

For the oldstable distribution (stretch), these problems have been fixed in version 4.9.168-1+deb9u5.

For the stable distribution (buster), these problems were mostly fixed in version 4.19.37-5+deb10u2 or earlier.

We recommend that you upgrade your linux packages.

For the detailed security status of linux please refer to its security tracker page at: https://security-tracker.debian.org/tracker/linux