OpenCloudOS-Kernel/samples
Kees Cook ef33f02968 bpf: Replace bpf_lpm_trie_key 0-length array with flexible array
[ Upstream commit 896880ff30866f386ebed14ab81ce1ad3710cfc4 ]

Replace deprecated 0-length array in struct bpf_lpm_trie_key with
flexible array. Found with GCC 13:

../kernel/bpf/lpm_trie.c:207:51: warning: array subscript i is outside array bounds of 'const __u8[0]' {aka 'const unsigned char[]'} [-Warray-bounds=]
  207 |                                        *(__be16 *)&key->data[i]);
      |                                                   ^~~~~~~~~~~~~
../include/uapi/linux/swab.h:102:54: note: in definition of macro '__swab16'
  102 | #define __swab16(x) (__u16)__builtin_bswap16((__u16)(x))
      |                                                      ^
../include/linux/byteorder/generic.h:97:21: note: in expansion of macro '__be16_to_cpu'
   97 | #define be16_to_cpu __be16_to_cpu
      |                     ^~~~~~~~~~~~~
../kernel/bpf/lpm_trie.c:206:28: note: in expansion of macro 'be16_to_cpu'
  206 |                 u16 diff = be16_to_cpu(*(__be16 *)&node->data[i]
^
      |                            ^~~~~~~~~~~
In file included from ../include/linux/bpf.h:7:
../include/uapi/linux/bpf.h:82:17: note: while referencing 'data'
   82 |         __u8    data[0];        /* Arbitrary size */
      |                 ^~~~

And found at run-time under CONFIG_FORTIFY_SOURCE:

  UBSAN: array-index-out-of-bounds in kernel/bpf/lpm_trie.c:218:49
  index 0 is out of range for type '__u8 [*]'

Changing struct bpf_lpm_trie_key is difficult since has been used by
userspace. For example, in Cilium:

	struct egress_gw_policy_key {
	        struct bpf_lpm_trie_key lpm_key;
	        __u32 saddr;
	        __u32 daddr;
	};

While direct references to the "data" member haven't been found, there
are static initializers what include the final member. For example,
the "{}" here:

        struct egress_gw_policy_key in_key = {
                .lpm_key = { 32 + 24, {} },
                .saddr   = CLIENT_IP,
                .daddr   = EXTERNAL_SVC_IP & 0Xffffff,
        };

To avoid the build time and run time warnings seen with a 0-sized
trailing array for struct bpf_lpm_trie_key, introduce a new struct
that correctly uses a flexible array for the trailing bytes,
struct bpf_lpm_trie_key_u8. As part of this, include the "header"
portion (which is just the "prefixlen" member), so it can be used
by anything building a bpf_lpr_trie_key that has trailing members that
aren't a u8 flexible array (like the self-test[1]), which is named
struct bpf_lpm_trie_key_hdr.

Unfortunately, C++ refuses to parse the __struct_group() helper, so
it is not possible to define struct bpf_lpm_trie_key_hdr directly in
struct bpf_lpm_trie_key_u8, so we must open-code the union directly.

Adjust the kernel code to use struct bpf_lpm_trie_key_u8 through-out,
and for the selftest to use struct bpf_lpm_trie_key_hdr. Add a comment
to the UAPI header directing folks to the two new options.

Reported-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Closes: https://paste.debian.net/hidden/ca500597/
Link: https://lore.kernel.org/all/202206281009.4332AA33@keescook/ [1]
Link: https://lore.kernel.org/bpf/20240222155612.it.533-kees@kernel.org
Stable-dep-of: 59f2f841179a ("bpf: Avoid kfree_rcu() under lock in bpf_lpm_trie.")
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-08-19 06:04:27 +02:00
..
acrn virt: acrn: Replace obsolete memalign() with posix_memalign() 2023-04-20 14:20:51 +02:00
auxdisplay .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
binderfs .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
bpf bpf: Replace bpf_lpm_trie_key 0-length array with flexible array 2024-08-19 06:04:27 +02:00
configfs treewide: remove editor modelines and cruft 2021-05-07 00:26:34 -07:00
connector .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
coresight coresight: syscfg: Example CoreSight configuration loadable module 2021-11-26 11:34:07 -07:00
fanotify Add gitignore file for samples/fanotify/ subdirectory 2021-11-07 11:19:24 -08:00
fprobe fprobe: Pass return address to the handlers 2023-06-06 21:39:55 +09:00
ftrace samples: ftrace: Replace bti assembly with hint for older compiler 2023-08-21 22:03:58 -04:00
hid bpf: Replace deprecated -target with --target= for Clang 2023-06-29 15:46:17 +02:00
hidraw .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
hw_breakpoint samples/hw_breakpoint: mark sample_hbp as static 2023-07-26 11:17:19 -07:00
kdb kdb: Rename members of struct kdbtab_t 2021-07-27 17:05:06 +01:00
kfifo samples/kfifo: Rename read_lock/write_lock 2021-10-13 14:36:48 +02:00
kmemleak kmemleak-test: drop __init to get better backtrace 2023-06-09 16:25:40 -07:00
kobject samples/kobject: make kobj_type structure constant 2023-02-08 13:34:41 +01:00
kprobes samples/kprobes: Add LoongArch support 2023-02-25 22:12:17 +08:00
landlock samples/landlock: Document best-effort approach for LANDLOCK_ACCESS_FS_REFER 2022-11-07 20:49:50 +01:00
livepatch livepatch: Reorder to use before freeing a pointer 2022-03-23 13:51:11 +01:00
mei samples: mei: don't wait on read completion upon write. 2021-08-01 09:54:22 +02:00
nitro_enclaves nitro_enclaves: Add fixes for checkpatch blank line reports 2021-09-14 11:11:20 +02:00
pfsm samples: Add userspace example for TI TPS6594 PFSM 2023-06-15 13:41:53 +02:00
pidfd .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
pktgen samples: pktgen: fix append mode failed issue 2023-07-03 09:15:26 +01:00
qmi soc: qcom: qmi: use const for struct qmi_elem_info 2022-08-29 17:33:01 -05:00
rpmsg
rust samples: rust: print: Add sample code for Arc printing 2023-04-10 05:05:43 +02:00
seccomp samples/seccomp: Adjust sample to also provide kill option 2022-02-10 19:09:12 -08:00
timers .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
trace_events tracing: Fix cpumask() example typo 2022-12-14 11:17:55 -05:00
trace_printk
uhid
user_events tracing/user_events: Use write ABI in example 2023-03-29 06:52:09 -04:00
v4l treewide: Replace GPLv2 boilerplate/reference with SPDX - gpl-2.0_168.RULE (part 2) 2022-06-10 14:51:36 +02:00
vfio-mdev vfio/mtty: Overhaul mtty interrupt handling 2024-01-10 17:16:55 +01:00
vfs .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
watch_queue .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
watchdog .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
Kconfig vfio-dev/mdpy-fb: Use fbdev I/O helpers 2023-08-04 15:54:39 +02:00
Makefile samples: Add userspace example for TI TPS6594 PFSM 2023-06-15 13:41:53 +02:00