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| author | David Vernet <void@manifault.com> | 2023-01-28 08:15:37 -0600 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2023-01-28 12:21:40 -0800 |
| commit | cb4a21ea592f5753ab54cd8688306cf6423783a8 (patch) | |
| tree | fdcc4ac5a343d517505452918798e38615e8e097 /kernel | |
| parent | 70eb3911d80f548a76fb9a40c8a3fd93ac061a42 (diff) | |
| download | linux-stable-cb4a21ea592f5753ab54cd8688306cf6423783a8.tar.gz linux-stable-cb4a21ea592f5753ab54cd8688306cf6423783a8.tar.bz2 linux-stable-cb4a21ea592f5753ab54cd8688306cf6423783a8.zip | |
bpf: Build-time assert that cpumask offset is zero
The first element of a struct bpf_cpumask is a cpumask_t. This is done
to allow struct bpf_cpumask to be cast to a struct cpumask. If this
element were ever moved to another field, any BPF program passing a
struct bpf_cpumask * to a kfunc expecting a const struct cpumask * would
immediately fail to load. Add a build-time assertion so this is
assumption is captured and verified.
Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230128141537.100777-1-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/cpumask.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/bpf/cpumask.c b/kernel/bpf/cpumask.c index 25355a0a367a..6bbb67dfc998 100644 --- a/kernel/bpf/cpumask.c +++ b/kernel/bpf/cpumask.c @@ -52,6 +52,9 @@ struct bpf_cpumask *bpf_cpumask_create(void) { struct bpf_cpumask *cpumask; + /* cpumask must be the first element so struct bpf_cpumask be cast to struct cpumask. */ + BUILD_BUG_ON(offsetof(struct bpf_cpumask, cpumask) != 0); + cpumask = bpf_mem_alloc(&bpf_cpumask_ma, sizeof(*cpumask)); if (!cpumask) return NULL; |