An issue was discovered in the Linux kernel before 5.11.8. kernel/bpf/verifier.c performs undesirable out-of-bounds speculation on pointer arithmetic, leading to side-channel attacks that defeat Spectre mitigations and obtain sensitive information from kernel memory, aka CID-f232326f6966. This affects pointer types that do not define a ptr_limit.

Affected: Ubuntu:18.04:LTS: linux-aws-5.4, Ubuntu:18.04:LTS: linux-azure-5.4, Ubuntu:18.04:LTS: linux-gcp-5.4, Ubuntu:18.04:LTS: linux-gke-5.3, Ubuntu:18.04:LTS: linux-gke-5.4, Ubuntu:18.04:LTS: linux-gkeop-5.4, Ubuntu:18.04:LTS: linux-hwe, Ubuntu:18.04:LTS: linux-hwe-5.4, Ubuntu:18.04:LTS: linux-oracle-5.4, Ubuntu:18.04:LTS: linux-raspi-5.4 and 12 more

De4dCr0w of 360 Alpha Lab discovered that the BPF verifier in the Linux kernel did not properly handle mod32 destination register truncation when the source register was known to be 0. A local attacker could use this to expose sensitive information (kernel memory) or possibly execute arbitrary code. (CVE-2021-3444)

Adam Nichols discovered that heap overflows existed in the iSCSI subsystem in the Linux kernel. A local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2021-27365)

Piotr Krysiuk discovered that the BPF subsystem in the Linux kernel did not properly compute a speculative execution limit on pointer arithmetic in some situations. A local attacker could use this to expose sensitive information (kernel memory). (CVE-2020-27171)

Piotr Krysiuk discovered that the BPF subsystem in the Linux kernel did not properly apply speculative execution limits on some pointer types. A local attacker could use this to expose sensitive information (kernel memory). (CVE-2020-27170)

Adam Nichols discovered that the iSCSI subsystem in the Linux kernel did not properly restrict access to iSCSI transport handles. A local attacker could use this to cause a denial of service or expose sensitive information (kernel pointer addresses). (CVE-2021-27363)

Adam Nichols discovered that an out-of-bounds read existed in the iSCSI subsystem in the Linux kernel. A local attacker could use this to cause a denial of service (system crash) o…