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CVE Request: Linux: Incorrect branch fixups for eBPF allow arbitrary read


From: Salvatore Bonaccorso <carnil () debian org>
Date: Sun, 14 Feb 2016 15:52:17 +0100

Hi

We would like to request a CVE for the following issue fixed in Linux
with the following commit, which as well contains an analysis:

https://git.kernel.org/linus/a1b14d27ed0965838350f1377ff97c93ee383492
(will be in v4.5-rc4):

When ctx access is used, the kernel often needs to expand/rewrite
instructions, so after that patching, branch offsets have to be
adjusted for both forward and backward jumps in the new eBPF program,
but for backward jumps it fails to account the delta. Meaning, for
example, if the expansion happens exactly on the insn that sits at
the jump target, it doesn't fix up the back jump offset.

The issue was introduced in v4.1-rc1 with commit
https://git.kernel.org/linus/9bac3d6d548e5cc925570b263f35b70a00a00ffd
.

Could you please assign a CVE for this issue?

Regards,
Salvatore


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