An issue was discovered in the Linux kernel before 5.11.8. kernel/bpf/verifier.c has an off-by-one error (with a resultant integer underflow) affecting 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-10d2bb2e6b1d.
https://www.openwall.com/lists/oss-security/2021/03/19/3
https://lists.debian.org/debian-lts-announce/2021/03/msg00035.html
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.8
http://www.openwall.com/lists/oss-security/2021/03/24/5
http://packetstormsecurity.com/files/162117/Kernel-Live-Patch-Security-Notice-LSN-0075-1.html