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While working on 16338a9b3ac3 ("bpf, arm64: fix out of bounds access in
tail call") I noticed that ppc64 JIT is partially affected as well. While
the bound checking is correctly performed as unsigned comparison, the
register with the index value however, is never truncated into 32 bit
space, so e.g. a index value of 0x100000000ULL with a map of 1 element
would pass with PPC_CMPLW() whereas we later on continue with the full
64 bit register value. Therefore, as we do in interpreter and other JITs
truncate the value to 32 bit initially in order to fix access.
Fixes: ce0761419fae ("powerpc/bpf: Implement support for tail calls")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.