Re: [PATCH][next] treewide: uapi: Replace zero-length arrays with flexible-array members

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]


On 6/27/22 8:04 PM, Gustavo A. R. Silva wrote:
There is a regular need in the kernel to provide a way to declare
having a dynamically sized set of trailing elements in a structure.
Kernel code should always use “flexible array members”[1] for these
cases. The older style of one-element or zero-length arrays should
no longer be used[2].

This code was transformed with the help of Coccinelle:
(linux-5.19-rc2$ spatch --jobs $(getconf _NPROCESSORS_ONLN) --sp-file script.cocci --include-headers --dir . > output.patch)

identifier S, member, array;
type T1, T2;

struct S {
   T1 member;
   T2 array[
- 0

-fstrict-flex-arrays=3 is coming and we need to land these changes
to prevent issues like these in the short future:

../fs/minix/dir.c:337:3: warning: 'strcpy' will always overflow; destination buffer has size 0,
but the source string has length 2 (including NUL byte) [-Wfortify-source]
		strcpy(de3->name, ".");

Since these are all [0] to [] changes, the risk to UAPI is nearly zero. If
this breaks anything, we can use a union with a new member name.


Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
Hi all!

JFYI: I'm adding this to my -next tree. :)

Fyi, this breaks BPF CI:

  progs/map_ptr_kern.c:314:26: error: field 'trie_key' with variable sized type 'struct bpf_lpm_trie_key' not at the end of a struct or class is a GNU extension [-Werror,-Wgnu-variable-sized-type-not-at-end]
          struct bpf_lpm_trie_key trie_key;
  1 error generated.
  make: *** [Makefile:519: /tmp/runner/work/bpf/bpf/tools/testing/selftests/bpf/map_ptr_kern.o] Error 1
  make: *** Waiting for unfinished jobs....
  Error: Process completed with exit code 2.

[Index of Archives]     [Linux Networking Development]     [Linux OMAP]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     SCTP

  Powered by Linux