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Filename Latest commit message Latest commit date
Jakub Kicinski 527db74b71 nfp: bpf: protect against mis-initializing atomic counters
Atomic operations on the NFP are currently always in big endian.
The driver keeps track of regions of memory storing atomic values
and byte swaps them accordingly.  There are corner cases where
the map values may be initialized before the driver knows they
are used as atomic counters.  This can happen either when the
datapath is performing the update and the stack contents are
unknown or when map is updated before the program which will
use it for atomic values is loaded.

To avoid situation where user initializes the value to 0 1 2 3
and then after loading a program which uses the word as an atomic
counter starts reading 3 2 1 0 - only allow atomic counters to be
initialized to endian-neutral values.

For updates from the datapath the stack information may not be
as precise, so just allow initializing such values to 0.

Example code which would break:
struct bpf_map_def SEC("maps") rxcnt = {
       .type = BPF_MAP_TYPE_HASH,
       .key_size = sizeof(__u32),
       .value_size = sizeof(__u64),
       .max_entries = 1,
};

int xdp_prog1()
{
      	__u64 nonzeroval = 3;
	__u32 key = 0;
	__u64 *value;

	value = bpf_map_lookup_elem(&rxcnt, &key);
	if (!value)
		bpf_map_update_elem(&rxcnt, &key, &nonzeroval, BPF_ANY);
	else
		__sync_fetch_and_add(value, 1);

	return XDP_PASS;
}

$ offload bpftool map dump
key: 00 00 00 00 value: 00 00 00 03 00 00 00 00

should be:

$ offload bpftool map dump
key: 00 00 00 00 value: 03 00 00 00 00 00 00 00

Reported-by: David Beckett <david.beckett@netronome.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2018-10-16 15:23:58 -07:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-10-12 21:38:46 -07:00
block blk-mq: I/O and timer unplugs are inverted in blktrace 2018-09-27 13:12:44 -06:00
certs
crypto
Documentation FDDI: defza: Add support for DEC FDDIcontroller 700 TURBOchannel adapter 2018-10-15 21:46:06 -07:00
drivers nfp: bpf: protect against mis-initializing atomic counters 2018-10-16 15:23:58 -07:00
firmware
fs Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-10-12 21:38:46 -07:00
include net: Enable kernel side filtering of route dumps 2018-10-16 00:14:07 -07:00
init
ipc ipc/shm.c: use ERR_CAST() for shm_lock() error return 2018-10-05 16:32:04 -07:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2018-10-15 23:21:07 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-10-12 21:38:46 -07:00
LICENSES
mm Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-10-11 12:27:47 +02:00
net net/ipv4: Bail early if user only wants prefix entries 2018-10-16 00:14:08 -07:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-10-12 21:38:46 -07:00
scripts Kbuild fixes for v4.19 (2nd) 2018-10-11 19:23:07 +02:00
security Revert "uapi/linux/keyctl.h: don't use C++ reserved keyword as a struct member name" 2018-09-25 13:28:58 +02:00
sound ALSA: hda/realtek - Cannot adjust speaker's volume on Dell XPS 27 7760 2018-10-04 07:50:48 +02:00
tools libbpf: Per-symbol visibility for DSO 2018-10-16 15:16:47 -07:00
usr
virt KVM: Remove obsolete kvm_unmap_hva notifier backend 2018-09-07 15:06:02 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2018-10-15 23:21:07 -07:00
Makefile Kbuild fixes for v4.19 (2nd) 2018-10-11 19:23:07 +02:00
README

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.