CVE-2024-43843: riscv, bpf: Fix out-of-bounds issue when preparing trampoline image

CVE-2024-43843: riscv, bpf: Fix out-of-bounds issue when preparing trampoline image

[Greg Kroah-Hartman]

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

riscv, bpf: Fix out-of-bounds issue when preparing trampoline image

We get the size of the trampoline image during the dry run phase and
allocate memory based on that size. The allocated image will then be
populated with instructions during the real patch phase. But after
commit 26ef208c209a ("bpf: Use arch_bpf_trampoline_size"), the `im`
argument is inconsistent in the dry run and real patch phase. This may
cause emit_imm in RV64 to generate a different number of instructions
when generating the 'im' address, potentially causing out-of-bounds
issues. Let's emit the maximum number of instructions for the "im"
address during dry run to fix this problem.

The Linux kernel CVE team has assigned CVE-2024-43843 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.8 with commit 26ef208c209a and fixed in 6.10.3 with commit 3e6a1b1b179a
	Issue introduced in 6.8 with commit 26ef208c209a and fixed in 6.11-rc1 with commit 9f1e16fb1fc9

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2024-43843
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	arch/riscv/net/bpf_jit_comp64.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/3e6a1b1b179abb643ec3560c02bc3082bc92285f
	https://git.kernel.org/stable/c/9f1e16fb1fc9826001c69e0551d51fbbcd2d74e9