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Yonghong Song 7c4f5ab63e bpf: Silence a warning in btf_type_id_size() 
[ Upstream commit e6c2f594ed ]

syzbot reported a warning in [1] with the following stacktrace:
  WARNING: CPU: 0 PID: 5005 at kernel/bpf/btf.c:1988 btf_type_id_size+0x2d9/0x9d0 kernel/bpf/btf.c:1988
  ...
  RIP: 0010:btf_type_id_size+0x2d9/0x9d0 kernel/bpf/btf.c:1988
  ...
  Call Trace:
   <TASK>
   map_check_btf kernel/bpf/syscall.c:1024 [inline]
   map_create+0x1157/0x1860 kernel/bpf/syscall.c:1198
   __sys_bpf+0x127f/0x5420 kernel/bpf/syscall.c:5040
   __do_sys_bpf kernel/bpf/syscall.c:5162 [inline]
   __se_sys_bpf kernel/bpf/syscall.c:5160 [inline]
   __x64_sys_bpf+0x79/0xc0 kernel/bpf/syscall.c:5160
   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
   do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
   entry_SYSCALL_64_after_hwframe+0x63/0xcd

With the following btf
  [1] DECL_TAG 'a' type_id=4 component_idx=-1
  [2] PTR '(anon)' type_id=0
  [3] TYPE_TAG 'a' type_id=2
  [4] VAR 'a' type_id=3, linkage=static
and when the bpf_attr.btf_key_type_id = 1 (DECL_TAG),
the following WARN_ON_ONCE in btf_type_id_size() is triggered:
  if (WARN_ON_ONCE(!btf_type_is_modifier(size_type) &&
                   !btf_type_is_var(size_type)))
          return NULL;

Note that 'return NULL' is the correct behavior as we don't want
a DECL_TAG type to be used as a btf_{key,value}_type_id even
for the case like 'DECL_TAG -> STRUCT'. So there
is no correctness issue here, we just want to silence warning.

To silence the warning, I added DECL_TAG as one of kinds in
btf_type_nosize() which will cause btf_type_id_size() returning
NULL earlier without the warning.

  [1] https://lore.kernel.org/bpf/000000000000e0df8d05fc75ba86@google.com/

Reported-by: syzbot+958967f249155967d42a@syzkaller.appspotmail.com
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20230530205029.264910-1-yhs@fb.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2023-07-27 08:56:49 +02:00
arch arm64: mm: fix VA-range sanity check 2023-07-27 08:56:47 +02:00
block blk-mq: fix NULL dereference on q->elevator in blk_mq_elv_switch_none 2023-07-27 08:56:45 +02:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto crypto: jitter - correct health test during initialization 2023-07-19 16:36:19 +02:00
Documentation media: uapi: Fix [GS]_ROUTING ACTIVE flag value 2023-07-23 13:54:08 +02:00
drivers wifi: rtw88: sdio: Check the HISR RX_REQUEST bit in rtw_sdio_rx_isr() 2023-07-27 08:56:49 +02:00
fs erofs: Fix detection of atomic context 2023-07-27 08:56:46 +02:00
include posix-timers: Ensure timer ID search-loop limit is valid 2023-07-27 08:56:45 +02:00
init kbuild: Fix CFI failures with GCOV 2023-07-19 16:36:23 +02:00
io_uring io_uring: Fix io_uring mmap() by using architecture-provided get_unmapped_area() 2023-07-27 08:56:31 +02:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel bpf: Silence a warning in btf_type_id_size() 2023-07-27 08:56:49 +02:00
lib maple_tree: set the node limit when creating a new root node 2023-07-27 08:56:32 +02:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm/mlock: fix vma iterator conversion of apply_vma_lock_flags() 2023-07-27 08:56:32 +02:00
net bpf: tcp: Avoid taking fast sock lock in iterator 2023-07-27 08:56:49 +02:00
rust Rust changes for v6.4 2023-04-30 11:20:22 -07:00
samples samples: ftrace: Save required argument registers in sample trampolines 2023-07-23 13:54:09 +02:00
scripts kbuild: add $(CLANG_FLAGS) to KBUILD_CPPFLAGS 2023-07-19 16:37:00 +02:00
security keys: Fix linking a duplicate key to a keyring's assoc_array 2023-07-27 08:56:32 +02:00
sound ALSA: hda/realtek: Add quirks for ROG ALLY CS35l41 audio 2023-07-27 08:56:44 +02:00
tools tools/nolibc: ensure stack protector guard is never zero 2023-07-27 08:56:48 +02:00
usr initramfs: Check negative timestamp to prevent broken cpio archive 2023-04-16 17:37:01 +09:00
virt KVM: Avoid illegal stage2 mapping on invalid memory slot 2023-06-22 15:14:57 -04:00
.clang-format cxl for v6.4 2023-04-30 11:51:51 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for *.dtso files 2023-02-26 15:28:23 +09:00
.gitignore linux-kselftest-kunit-6.4-rc1 2023-04-24 12:31:32 -07:00
.mailmap mailmap: add entries for Ben Dooks 2023-06-19 13:19:35 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: sctp: move Neil to CREDITS 2023-05-12 08:51:32 +01:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Networking fixes for 6.4-rc8, including fixes from ipsec, bpf, 2023-06-22 17:59:51 -07:00
Makefile Linux 6.4.6 2023-07-24 18:56:41 +02:00
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.