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Martin KaFai Lau 93c230e3f5 bpf: Enforce id generation for all may-be-null register type 
The commit af7ec13833 ("bpf: Add bpf_skc_to_tcp6_sock() helper")
introduces RET_PTR_TO_BTF_ID_OR_NULL and
the commit eaa6bcb71e ("bpf: Introduce bpf_per_cpu_ptr()")
introduces RET_PTR_TO_MEM_OR_BTF_ID_OR_NULL.
Note that for RET_PTR_TO_MEM_OR_BTF_ID_OR_NULL, the reg0->type
could become PTR_TO_MEM_OR_NULL which is not covered by
BPF_PROBE_MEM.

The BPF_REG_0 will then hold a _OR_NULL pointer type. This _OR_NULL
pointer type requires the bpf program to explicitly do a NULL check first.
After NULL check, the verifier will mark all registers having
the same reg->id as safe to use.  However, the reg->id
is not set for those new _OR_NULL return types.  One of the ways
that may be wrong is, checking NULL for one btf_id typed pointer will
end up validating all other btf_id typed pointers because
all of them have id == 0.  The later tests will exercise
this path.

To fix it and also avoid similar issue in the future, this patch
moves the id generation logic out of each individual RET type
test in check_helper_call().  Instead, it does one
reg_type_may_be_null() test and then do the id generation
if needed.

This patch also adds a WARN_ON_ONCE in mark_ptr_or_null_reg()
to catch future breakage.

The _OR_NULL pointer usage in the bpf_iter_reg.ctx_arg_info is
fine because it just happens that the existing id generation after
check_ctx_access() has covered it.  It is also using the
reg_type_may_be_null() to decide if id generation is needed or not.

Fixes: af7ec13833 ("bpf: Add bpf_skc_to_tcp6_sock() helper")
Fixes: eaa6bcb71e ("bpf: Introduce bpf_per_cpu_ptr()")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201019194212.1050855-1-kafai@fb.com
History 2020-10-19 15:57:42 -07:00
arch networking changes for the 5.10 merge window 2020-10-15 18:42:13 -07:00
block - Improve DM core's bio splitting to use blk_max_size_offset(). Also 2020-10-14 15:05:38 -07:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto drivers-5.10-2020-10-12 2020-10-13 13:04:41 -07:00
Documentation icmp: randomize the global rate limiter 2020-10-16 16:47:09 -07:00
drivers ixgbe: fix probing of multi-port devices with one MDIO 2020-10-18 13:01:22 -07:00
fs networking changes for the 5.10 merge window 2020-10-15 18:42:13 -07:00
include networking changes for the 5.10 merge window 2020-10-15 18:42:13 -07:00
init networking changes for the 5.10 merge window 2020-10-15 18:42:13 -07:00
ipc ipc: adjust proc_ipc_sem_dointvec definition to match prototype 2020-09-05 12:14:29 -07:00
kernel bpf: Enforce id generation for all may-be-null register type 2020-10-19 15:57:42 -07:00
lib networking changes for the 5.10 merge window 2020-10-15 18:42:13 -07:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm networking changes for the 5.10 merge window 2020-10-15 18:42:13 -07:00
net net: core: use list_del_init() instead of list_del() in netdev_run_todo() 2020-10-18 14:50:25 -07:00
samples networking changes for the 5.10 merge window 2020-10-15 18:42:13 -07:00
scripts networking changes for the 5.10 merge window 2020-10-15 18:42:13 -07:00
security networking changes for the 5.10 merge window 2020-10-15 18:42:13 -07:00
sound dma-mapping updates for 5.10 2020-10-15 14:43:29 -07:00
tools selftests: forwarding: Add missing 'rp_filter' configuration 2020-10-18 12:47:32 -07:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt KVM: fix memory leak in kvm_io_bus_unregister_dev() 2020-09-11 13:15:11 -04:00
.clang-format memblock: use separate iterators for memory and reserved regions 2020-10-13 18:38:35 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: docs: ignore sphinx_*/ directories 2020-09-10 10:44:31 -06:00
.mailmap As hoped, things calmed down for docs this cycle; fewer changes and almost 2020-10-12 16:21:29 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS networking changes for the 5.10 merge window 2020-10-15 18:42:13 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS networking changes for the 5.10 merge window 2020-10-15 18:42:13 -07:00
Makefile networking changes for the 5.10 merge window 2020-10-15 18:42:13 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.

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.