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| author | Arnd Bergmann <arnd@arndb.de> | 2020-04-30 23:30:47 +0200 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2020-05-04 22:54:42 +0200 |
| commit | d26c0cc53950464a24adfa76867f1d71f0cbbea6 (patch) | |
| tree | 31d9b92c73807fe11c553dbbf5b78770f8fa15d7 | |
| parent | c648c9c7429e979ca081359f39b6902aed92d490 (diff) | |
| download | linux-d26c0cc53950464a24adfa76867f1d71f0cbbea6.tar.bz2 | |
bpf: Avoid gcc-10 stringop-overflow warning in struct bpf_prog
gcc-10 warns about accesses to zero-length arrays:
kernel/bpf/core.c: In function 'bpf_patch_insn_single':
cc1: warning: writing 8 bytes into a region of size 0 [-Wstringop-overflow=]
In file included from kernel/bpf/core.c:21:
include/linux/filter.h:550:20: note: at offset 0 to object 'insnsi' with size 0 declared here
550 | struct bpf_insn insnsi[0];
| ^~~~~~
In this case, we really want to have two flexible-array members,
but that is not possible. Removing the union to make insnsi a
flexible-array member while leaving insns as a zero-length array
fixes the warning, as nothing writes to the other one in that way.
This trick only works on linux-3.18 or higher, as older versions
had additional members in the union.
Fixes: 60a3b2253c41 ("net: bpf: make eBPF interpreter images read-only")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200430213101.135134-6-arnd@arndb.de
| -rw-r--r-- | include/linux/filter.h | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/include/linux/filter.h b/include/linux/filter.h index af37318bb1c5..73d06a39e2d6 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -545,10 +545,8 @@ struct bpf_prog { unsigned int (*bpf_func)(const void *ctx, const struct bpf_insn *insn); /* Instructions for interpreter */ - union { - struct sock_filter insns[0]; - struct bpf_insn insnsi[0]; - }; + struct sock_filter insns[0]; + struct bpf_insn insnsi[]; }; struct sk_filter { |