From: Thorsten Blum <thorsten.blum@linux.dev>
Date: Mon, 28 Apr 2025 21:06:39 +0000 (+0200)
Subject: bpf: Replace offsetof() with struct_size()
X-Git-Tag: v6.16-rc1~131^2~48
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=7b05f43155cb128aa06a226afdbc3daa8d75b358;p=linux-2.6-block.git

bpf: Replace offsetof() with struct_size()

Compared to offsetof(), struct_size() provides additional compile-time
checks for structs with flexible arrays (e.g., __must_be_array()).

No functional changes intended.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250428210638.30219-2-thorsten.blum@linux.dev
---

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 64c3393e8270..df33d19c5c3b 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -36,6 +36,7 @@
 #include <linux/memcontrol.h>
 #include <linux/trace_events.h>
 #include <linux/tracepoint.h>
+#include <linux/overflow.h>
 
 #include <net/netfilter/nf_bpf_link.h>
 #include <net/netkit.h>
@@ -693,7 +694,7 @@ struct btf_record *btf_record_dup(const struct btf_record *rec)
 
 	if (IS_ERR_OR_NULL(rec))
 		return NULL;
-	size = offsetof(struct btf_record, fields[rec->cnt]);
+	size = struct_size(rec, fields, rec->cnt);
 	new_rec = kmemdup(rec, size, GFP_KERNEL | __GFP_NOWARN);
 	if (!new_rec)
 		return ERR_PTR(-ENOMEM);
@@ -748,7 +749,7 @@ bool btf_record_equal(const struct btf_record *rec_a, const struct btf_record *r
 		return false;
 	if (rec_a->cnt != rec_b->cnt)
 		return false;
-	size = offsetof(struct btf_record, fields[rec_a->cnt]);
+	size = struct_size(rec_a, fields, rec_a->cnt);
 	/* btf_parse_fields uses kzalloc to allocate a btf_record, so unused
 	 * members are zeroed out. So memcmp is safe to do without worrying
 	 * about padding/unused fields.