b799207e1e
When I wrote commit468f6eafa6("bpf: fix 32-bit ALU op verification"), I assumed that, in order to emulate 64-bit arithmetic with 32-bit logic, it is sufficient to just truncate the output to 32 bits; and so I just moved the register size coercion that used to be at the start of the function to the end of the function. That assumption is true for almost every op, but not for 32-bit right shifts, because those can propagate information towards the least significant bit. Fix it by always truncating inputs for 32-bit ops to 32 bits. Also get rid of the coerce_reg_to_size() after the ALU op, since that has no effect. Fixes:468f6eafa6("bpf: fix 32-bit ALU op verification") Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
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.