linux-kernel - [PATCH] crypto: deflate - Use struct_size to improve deflate_alloc

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Message-ID: <20251030163218.497730-1-thorsten.blum@linux.dev>
Date: Thu, 30 Oct 2025 17:32:17 +0100
From: Thorsten Blum <thorsten.blum@...ux.dev>
To: Herbert Xu <herbert@...dor.apana.org.au>,
	"David S. Miller" <davem@...emloft.net>
Cc: Thorsten Blum <thorsten.blum@...ux.dev>,
	linux-crypto@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] crypto: deflate - Use struct_size to improve deflate_alloc_stream

Use struct_size(), which provides additional compile-time checks for
structures with flexible array members (e.g., __must_be_array()), to
calculate the allocation size for a new 'deflate_stream'.

Signed-off-by: Thorsten Blum <thorsten.blum@...ux.dev>
---
 crypto/deflate.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/crypto/deflate.c b/crypto/deflate.c
index 21404515dc77..a3e1fff55661 100644
--- a/crypto/deflate.c
+++ b/crypto/deflate.c
@@ -15,6 +15,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
+#include <linux/overflow.h>
 #include <linux/percpu.h>
 #include <linux/scatterlist.h>
 #include <linux/slab.h>
@@ -39,7 +40,7 @@ static void *deflate_alloc_stream(void)
 						     DEFLATE_DEF_MEMLEVEL));
 	struct deflate_stream *ctx;
 
-	ctx = kvmalloc(sizeof(*ctx) + size, GFP_KERNEL);
+	ctx = kvmalloc(struct_size(ctx, workspace, size), GFP_KERNEL);
 	if (!ctx)
 		return ERR_PTR(-ENOMEM);
 
-- 
2.51.0