[PATCH v3 06/13] lib/crypto: sm3: Provide a function for zeroizing the sm3_ctx structure
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From: Thomas Huth <hidden>
Date: 2026-09-10 12:42:16
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lkml
Subsystem:
crypto api, crypto library, library code, the rest · Maintainers:
Herbert Xu, "David S. Miller", Eric Biggers, Jason A. Donenfeld, Ard Biesheuvel, Andrew Morton, Linus Torvalds
Revision v3 of 4 in this series.
Revisions (4)
- v1 [diff vs current]
- v2 [diff vs current]
- v3 current
- v4 [diff vs current]
In certain cases crypto code functions need to zeroize their local sm3_ctx structure after use to avoid leaking sensitive material. Provide a sm3_zeroize_ctx() helper function that e.g. can be used with __cleanup() to automatically zeroize the structure when it goes out of scope. While we're at it, replace the related memzero_explicit() call in lib/crypto/sm3.c with a call to the new helper function. Signed-off-by: Thomas Huth <redacted> --- include/crypto/sm3.h | 10 ++++++++++ lib/crypto/sm3.c | 2 +- 2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/include/crypto/sm3.h b/include/crypto/sm3.h
index 371e8a6617054..d044ca80213ba 100644
--- a/include/crypto/sm3.h
+++ b/include/crypto/sm3.h@@ -11,6 +11,7 @@ #define _CRYPTO_SM3_H #include <linux/types.h> +#include <linux/string.h> #define SM3_DIGEST_SIZE 32 #define SM3_BLOCK_SIZE 64
@@ -41,6 +42,15 @@ struct sm3_ctx { u8 buf[SM3_BLOCK_SIZE] __aligned(__alignof__(__be64)); }; +/** + * sm3_zeroize_ctx() - Zeroize an sm3_ctx structure + * @ctx: The sm3_ctx to zeroize + */ +static inline void sm3_zeroize_ctx(struct sm3_ctx *ctx) +{ + memzero_explicit(ctx, sizeof(*ctx)); +} + /** * sm3_init() - Initialize an SM3 context for a new message * @ctx: the context to initialize
diff --git a/lib/crypto/sm3.c b/lib/crypto/sm3.c
index b02b8a247adf2..23059347b4493 100644
--- a/lib/crypto/sm3.c
+++ b/lib/crypto/sm3.c@@ -258,7 +258,7 @@ static void __sm3_final(struct sm3_ctx *ctx, u8 out[SM3_DIGEST_SIZE]) void sm3_final(struct sm3_ctx *ctx, u8 out[SM3_DIGEST_SIZE]) { __sm3_final(ctx, out); - memzero_explicit(ctx, sizeof(*ctx)); + sm3_zeroize_ctx(ctx); } EXPORT_SYMBOL_GPL(sm3_final);
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2.55.0