Linux : Security Vulnerabilities, CVEs, Published In July 2019

In the Linux kernel before 5.2.3, drivers/block/floppy.c allows a denial of service by setup_format_params division-by-zero. Two consecutive ioctls can trigger the bug: the first one should set the drive geometry with .sect and .rate values that make F_SECT_PER_TRACK be zero. Next, the floppy format operation should be called. It can be triggered by an unprivileged local user even when a floppy disk has not been inserted. NOTE: QEMU creates the floppy device by default.

In the Linux kernel before 5.2.3, set_geometry in drivers/block/floppy.c does not validate the sect and head fields, as demonstrated by an integer overflow and out-of-bounds read. It can be triggered by an unprivileged local user when a floppy disk has been inserted. NOTE: QEMU creates the floppy device by default.

In the Linux kernel through 5.2.1 on the powerpc platform, when hardware transactional memory is disabled, a local user can cause a denial of service (TM Bad Thing exception and system crash) via a sigreturn() system call that sends a crafted signal frame. This affects arch/powerpc/kernel/signal_32.c and arch/powerpc/kernel/signal_64.c.

In parse_hid_report_descriptor in drivers/input/tablet/gtco.c in the Linux kernel through 5.2.1, a malicious USB device can send an HID report that triggers an out-of-bounds write during generation of debugging messages.

In the Linux kernel before 5.1.17, ptrace_link in kernel/ptrace.c mishandles the recording of the credentials of a process that wants to create a ptrace relationship, which allows local users to obtain root access by leveraging certain scenarios with a parent-child process relationship, where a parent drops privileges and calls execve (potentially allowing control by an attacker). One contributing factor is an object lifetime issue (which can also cause a panic). Another contributing factor is incorrect marking of a ptrace relationship as privileged, which is exploitable through (for example) Polkit's pkexec helper with PTRACE_TRACEME. NOTE: SELinux deny_ptrace might be a usable workaround in some environments.

In arch/x86/lib/insn-eval.c in the Linux kernel before 5.1.9, there is a use-after-free for access to an LDT entry because of a race condition between modify_ldt() and a #BR exception for an MPX bounds violation.

The Linux kernel 4.x (starting from 4.1) and 5.x before 5.0.8 allows Information Exposure (partial kernel address disclosure), leading to a KASLR bypass. Specifically, it is possible to extract the KASLR kernel image offset using the IP ID values the kernel produces for connection-less protocols (e.g., UDP and ICMP). When such traffic is sent to multiple destination IP addresses, it is possible to obtain hash collisions (of indices to the counter array) and thereby obtain the hashing key (via enumeration). This key contains enough bits from a kernel address (of a static variable) so when the key is extracted (via enumeration), the offset of the kernel image is exposed. This attack can be carried out remotely, by the attacker forcing the target device to send UDP or ICMP (or certain other) traffic to attacker-controlled IP addresses. Forcing a server to send UDP traffic is trivial if the server is a DNS server. ICMP traffic is trivial if the server answers ICMP Echo requests (ping). For client targets, if the target visits the attacker's web page, then WebRTC or gQUIC can be used to force UDP traffic to attacker-controlled IP addresses. NOTE: this attack against KASLR became viable in 4.1 because IP ID generation was changed to have a dependency on an address associated with a network namespace.

In the Linux kernel before 5.1.7, a device can be tracked by an attacker using the IP ID values the kernel produces for connection-less protocols (e.g., UDP and ICMP). When such traffic is sent to multiple destination IP addresses, it is possible to obtain hash collisions (of indices to the counter array) and thereby obtain the hashing key (via enumeration). An attack may be conducted by hosting a crafted web page that uses WebRTC or gQUIC to force UDP traffic to attacker-controlled IP addresses.

A flaw was found in the Linux kernel's freescale hypervisor manager implementation, kernel versions 5.0.x up to, excluding 5.0.17. A parameter passed to an ioctl was incorrectly validated and used in size calculations for the page size calculation. An attacker can use this flaw to crash the system, corrupt memory, or create other adverse security affects.

An issue was discovered in the Linux kernel before 4.18.7. In block/blk-core.c, there is an __blk_drain_queue() use-after-free because a certain error case is mishandled.

An issue was discovered in the Linux kernel before 4.18.7. In create_qp_common in drivers/infiniband/hw/mlx5/qp.c, mlx5_ib_create_qp_resp was never initialized, resulting in a leak of stack memory to userspace.

An issue was discovered in the Linux kernel before 4.20. drivers/phy/mscc/phy-ocelot-serdes.c has an off-by-one error with a resultant ctrl->phys out-of-bounds read.

A flaw was found in the Linux kernel's NFS implementation, all versions 3.x and all versions 4.x up to 4.20. An attacker, who is able to mount an exported NFS filesystem, is able to trigger a null pointer dereference by using an invalid NFS sequence. This can panic the machine and deny access to the NFS server. Any outstanding disk writes to the NFS server will be lost.

In the Linux kernel before 4.14, an out of boundary access happened in drivers/nvme/target/fc.c.

In the Linux kernel before 4.9.6, there is an off by one in the drivers/mtd/spi-nor/cadence-quadspi.c cqspi_setup_flash() function. There are CQSPI_MAX_CHIPSELECT elements in the ->f_pdata array so the ">" should be ">=" instead.

In the Linux kernel before 4.1.4, a buffer overflow occurs when checking userspace params in drivers/media/dvb-frontends/cx24116.c. The maximum size for a DiSEqC command is 6, according to the userspace API. However, the code allows larger values such as 23.

In the Linux kernel before 3.4, a buffer overflow occurs in drivers/net/wireless/iwlwifi/iwl-agn-sta.c, which will cause at least memory corruption.

In the Linux kernel before 3.1, an off by one in the drivers/target/loopback/tcm_loop.c tcm_loop_make_naa_tpg() function could result in at least memory corruption.

In the Linux kernel before 2.6.37, an out of bounds array access happened in drivers/net/mlx4/port.c. When searching for a free entry in either mlx4_register_vlan() or mlx4_register_mac(), and there is no free entry, the loop terminates without updating the local variable free thus causing out of array bounds access.

In the Linux kernel before 2.6.34, a range check issue in drivers/gpu/drm/radeon/atombios.c could cause an off by one (buffer overflow) problem. NOTE: At least one Linux maintainer believes that this CVE is incorrectly assigned and should be rejected because the value is hard coded and are not user-controllable where it is used

In the Linux kernel before 2.6.20, there is an off-by-one bug in net/netlabel/netlabel_cipso_v4.c where it is possible to overflow the doi_def->tags[] array.