On Mon, Mar 25, 2024 at 03:01:56PM -0600, Gustavo A. R. Silva wrote:
> -Wflex-array-member-not-at-end is coming in GCC-14, and we are getting
> ready to enable it globally.
>
> Use the `__struct_group()` helper to separate the flexible array
> from the rest of the members in flexible `struct nx842_crypto_header`,
> through tagged `struct nx842_crypto_header_hdr`, and avoid embedding
> the flexible-array member in the middle of `struct nx842_crypto_ctx`.
>
> Also, use `container_of()` whenever we need to retrieve a pointer to
> the flexible structure.
>
> This code was detected with the help of Coccinelle, and audited and
> modified manually.
>
> Link: https://github.com/KSPP/linux/issues/202
> Signed-off-by: Gustavo A. R. Silva
> ---
> drivers/crypto/nx/nx-842.c | 6 --
> drivers/crypto/nx/nx-842.h | 11 +++
> 2 files changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/crypto/nx/nx-842.c b/drivers/crypto/nx/nx-842.c
> index 2ab90ec10e61..82214cde2bcd 100644
> --- a/drivers/crypto/nx/nx-842.c
> +++ b/drivers/crypto/nx/nx-842.c
> @@ -251,7 +251,9 @@ int nx842_crypto_compress(struct crypto_tfm *tfm,
> u8 *dst, unsigned int *dlen)
> {
> struct nx842_crypto_ctx *ctx = crypto_tfm_ctx(tfm);
> - struct nx842_crypto_header *hdr = >header;
> + struct nx842_crypto_header *hdr =
> + container_of(>header,
> + struct nx842_crypto_header, hdr);
> struct nx842_crypto_param p;
> struct nx842_constraints c = *ctx->driver->constraints;
> unsigned int groups, hdrsize, h;
> @@ -490,7 +492,7 @@ int nx842_crypto_decompress(struct crypto_tfm *tfm,
> }
>
> memcpy(>header, src, hdr_len);
> - hdr = >header;
> + hdr = container_of(>header, struct nx842_crypto_header, hdr);
>
> for (n = 0; n < hdr->groups; n++) {
> /* ignore applies to last group */
> diff --git a/drivers/crypto/nx/nx-842.h b/drivers/crypto/nx/nx-842.h
> index 7590bfb24d79..1f42c83d2683 100644
> --- a/drivers/crypto/nx/nx-842.h
> +++ b/drivers/crypto/nx/nx-842.h
> @@ -157,9 +157,12 @@ struct nx842_crypto_header_group {
> } __packed;
>
> struct nx842_crypto_header {
> - __be16 magic; /* NX842_CRYPTO_MAGIC */
> - __be16 ignore; /* decompressed end bytes to ignore */
> - u8 groups; /* total groups in this header */
> + /* New members must be added within the __struct_group() macro below. */
> + __struct_group(nx842_crypto_header_hdr, hdr, __packed,
> + __be16 magic; /* NX842_CRYPTO_MAGIC */
> + __be16 ignore; /* decompressed end bytes to ignore */
> + u8 groups; /* total groups in this header */
> + );
> struct nx842_crypto_header_group group[];
> } __packed;
>
> @@ -171,7 +174,7 @@ struct nx842_crypto_ctx {
> u8 *wmem;
> u8 *sbounce, *dbounce;
>
> - struct nx842_crypto_header header;
> + struct nx842_crypto_header_hdr header;
> struct nx842_crypto_header_group group[NX842_CRYPTO_GROUP_MAX];
>
> struct nx842_driver *driver;
Hmm. I think commit 03952d980153 ("crypto: nx - make platform drivers
directly register with crypto") incorrectly added "struct nx842_driver
*driver" to the end of struct nx842_crypto_ctx. I think it should be
before "header".
Then I see:
#define NX842_CRYPTO_HEADER_SIZE(g) \
(sizeof(struct nx842_crypto_header) + \
sizeof(struct nx842_crypto_header_group) * (g))
This is just struct_size(), really. And nothing uses:
#define NX842_CRYPTO_HEADER_MAX_SIZE\
NX842_CRYPTO_HEADER_SIZE(NX842_CRYPTO_GROUP_MAX)
And then looking for what uses struct nx842_crypto_ctx's "group" member,
I don't see anything except some sizeof()s:
drivers/crypto/nx/nx-common-powernv.c:1044: .cra_ctxsize = sizeof(struct
nx842_crypto_ctx),
drivers/crypto/nx/nx-common-pseries.c:1021: .cra_ctxsize = sizeof(struct
nx842_crypto_ctx),
This is just a maximally sized ctx (as if the group count were
NX842_CRYPTO_GROUP_MAX), which we could use struct_size for again:
.cra_ctxsize = struct_size_t(struct nx842_crypto_ctx, header.group,
NX842_CRYPTO_GROUP_MAX),
So then "group" can be entirely removed from struct nx842_crypto_ctx.
The result means we can also add __counted_by:
diff --git a/drivers/crypto/nx/nx-842.c b/drivers/crypto/nx/nx-842.c
index 2ab90ec10e61..144972fe2e6f 100644
--- a/drivers/crypto/nx/nx-842.c
+++ b/drivers/crypto/nx/nx-842.c
@@ -62,10 +62,7 @@
*/
#define NX842_CRYPTO_MAGIC (0xf842)
#define NX842_CRYPTO_HEADER_SIZE(g)\
- (sizeof(struct nx842_crypto_header) + \
-sizeof(struct nx842_crypto_header_group) * (g))
-#define NX842_CRYPTO_HEADER_MAX_SIZE \
-
