29ac604e62
Commit 38ca93060163 ("bpf, arm32: save 4 bytes of unneeded stack
space") messed up STACK_VAR() by 4 bytes presuming it was related
to skb scratch buffer space, but it clearly isn't as this refers
to the top word in stack, therefore restore it. This fixes a NULL
pointer dereference seen during bootup when JIT is enabled and BPF
program run in sk_filter_trim_cap() triggered by systemd-udevd.
JIT rework in 1c35ba122d4a ("ARM: net: bpf: use negative numbers
for stacked registers") and 96cced4e774a ("ARM: net: bpf: access
eBPF scratch space using ARM FP register") removed the affected
parts, so only needed in 4.18 stable.
Fixes: 38ca93060163 ("bpf, arm32: save 4 bytes of unneeded stack space")
Reported-by: Peter Robinson <pbrobinson@gmail.com>
Reported-by: Marc Haber <mh+netdev@zugschlus.de>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Tested-by: Peter Robinson <pbrobinson@gmail.com>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
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.