crypto: Replace zero-length array with flexible-array member

The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/drivers/crypto/caam/caamalg.c b/drivers/crypto/caam/caamalg.c
index 03797f9..b7bb7c3 100644 (file)
--- a/drivers/crypto/caam/caamalg.c
+++ b/drivers/crypto/caam/caamalg.c
@@ -909,7 +909,7 @@ struct skcipher_edesc {
        bool bklog;
        dma_addr_t sec4_sg_dma;
        struct sec4_sg_entry *sec4_sg;
-       u32 hw_desc[0];
+       u32 hw_desc[];
 };
 
 static void caam_unmap(struct device *dev, struct scatterlist *src,

diff --git a/drivers/crypto/caam/caamalg_qi.c b/drivers/crypto/caam/caamalg_qi.c
index 4a29e0e..27e36bd 100644 (file)
--- a/drivers/crypto/caam/caamalg_qi.c
+++ b/drivers/crypto/caam/caamalg_qi.c
@@ -783,7 +783,7 @@ struct aead_edesc {
        unsigned int assoclen;
        dma_addr_t assoclen_dma;
        struct caam_drv_req drv_req;
-       struct qm_sg_entry sgt[0];
+       struct qm_sg_entry sgt[];
 };
 
 /*
@@ -803,7 +803,7 @@ struct skcipher_edesc {
        int qm_sg_bytes;
        dma_addr_t qm_sg_dma;
        struct caam_drv_req drv_req;
-       struct qm_sg_entry sgt[0];
+       struct qm_sg_entry sgt[];
 };
 
 static struct caam_drv_ctx *get_drv_ctx(struct caam_ctx *ctx,

diff --git a/drivers/crypto/caam/caamalg_qi2.h b/drivers/crypto/caam/caamalg_qi2.h
index 7067367..f29cb7b 100644 (file)
--- a/drivers/crypto/caam/caamalg_qi2.h
+++ b/drivers/crypto/caam/caamalg_qi2.h
@@ -114,7 +114,7 @@ struct aead_edesc {
        dma_addr_t qm_sg_dma;
        unsigned int assoclen;
        dma_addr_t assoclen_dma;
-       struct dpaa2_sg_entry sgt[0];
+       struct dpaa2_sg_entry sgt[];
 };
 
 /*
@@ -132,7 +132,7 @@ struct skcipher_edesc {
        dma_addr_t iv_dma;
        int qm_sg_bytes;
        dma_addr_t qm_sg_dma;
-       struct dpaa2_sg_entry sgt[0];
+       struct dpaa2_sg_entry sgt[];
 };
 
 /*
@@ -146,7 +146,7 @@ struct ahash_edesc {
        dma_addr_t qm_sg_dma;
        int src_nents;
        int qm_sg_bytes;
-       struct dpaa2_sg_entry sgt[0];
+       struct dpaa2_sg_entry sgt[];
 };
 
 /**

diff --git a/drivers/crypto/caam/caamhash.c b/drivers/crypto/caam/caamhash.c
index 2fe8528..943bc02 100644 (file)
--- a/drivers/crypto/caam/caamhash.c
+++ b/drivers/crypto/caam/caamhash.c
@@ -536,7 +536,7 @@ struct ahash_edesc {
        int sec4_sg_bytes;
        bool bklog;
        u32 hw_desc[DESC_JOB_IO_LEN_MAX / sizeof(u32)] ____cacheline_aligned;
-       struct sec4_sg_entry sec4_sg[0];
+       struct sec4_sg_entry sec4_sg[];
 };
 
 static inline void ahash_unmap(struct device *dev,

diff --git a/drivers/crypto/cavium/nitrox/nitrox_main.c b/drivers/crypto/cavium/nitrox/nitrox_main.c
index c4632d8..e91be9b 100644 (file)
--- a/drivers/crypto/cavium/nitrox/nitrox_main.c
+++ b/drivers/crypto/cavium/nitrox/nitrox_main.c
@@ -71,7 +71,7 @@ struct ucode {
        char version[VERSION_LEN - 1];
        __be32 code_size;
        u8 raz[12];
-       u64 code[0];
+       u64 code[];
 };
 
 /**

diff --git a/drivers/crypto/chelsio/chcr_core.h b/drivers/crypto/chelsio/chcr_core.h
index e51c138..a4b9337 100644 (file)
--- a/drivers/crypto/chelsio/chcr_core.h
+++ b/drivers/crypto/chelsio/chcr_core.h
@@ -68,7 +68,7 @@ struct _key_ctx {
        __be32 ctx_hdr;
        u8 salt[MAX_SALT];
        __be64 iv_to_auth;
-       unsigned char key[0];
+       unsigned char key[];
 };
 
 #define KEYCTX_TX_WR_IV_S  55

diff --git a/drivers/crypto/mediatek/mtk-sha.c b/drivers/crypto/mediatek/mtk-sha.c
index 9e9f48b..bd6309e 100644 (file)
--- a/drivers/crypto/mediatek/mtk-sha.c
+++ b/drivers/crypto/mediatek/mtk-sha.c
@@ -107,7 +107,7 @@ struct mtk_sha_ctx {
        u8 id;
        u8 buf[SHA_BUF_SIZE] __aligned(sizeof(u32));
 
-       struct mtk_sha_hmac_ctx base[0];
+       struct mtk_sha_hmac_ctx base[];
 };
 
 struct mtk_sha_drv {

diff --git a/drivers/crypto/nx/nx.h b/drivers/crypto/nx/nx.h
index 91c5428..c623317 100644 (file)
--- a/drivers/crypto/nx/nx.h
+++ b/drivers/crypto/nx/nx.h
@@ -37,7 +37,7 @@ struct max_sync_cop {
        u32 fc;
        u32 mode;
        u32 triplets;
-       struct msc_triplet trip[0];
+       struct msc_triplet trip[];
 } __packed;
 
 struct alg_props {

diff --git a/drivers/crypto/omap-sham.c b/drivers/crypto/omap-sham.c
index 4f915a4..e4072cd 100644 (file)
--- a/drivers/crypto/omap-sham.c
+++ b/drivers/crypto/omap-sham.c
@@ -159,7 +159,7 @@ struct omap_sham_reqctx {
        int                     sg_len;
        unsigned int            total;  /* total request */
 
-       u8                      buffer[0] OMAP_ALIGNED;
+       u8                      buffer[] OMAP_ALIGNED;
 };
 
 struct omap_sham_hmac_ctx {
@@ -176,7 +176,7 @@ struct omap_sham_ctx {
        /* fallback stuff */
        struct crypto_shash     *fallback;
 
-       struct omap_sham_hmac_ctx base[0];
+       struct omap_sham_hmac_ctx base[];
 };
 
 #define OMAP_SHAM_QUEUE_LENGTH 10

diff --git a/include/crypto/if_alg.h b/include/crypto/if_alg.h
index 24cfa96..56527c8 100644 (file)
--- a/include/crypto/if_alg.h
+++ b/include/crypto/if_alg.h
@@ -66,7 +66,7 @@ struct af_alg_sgl {
 struct af_alg_tsgl {
        struct list_head list;
        unsigned int cur;               /* Last processed SG entry */
-       struct scatterlist sg[0];       /* Array of SGs forming the SGL */
+       struct scatterlist sg[];        /* Array of SGs forming the SGL */
 };
 
 #define MAX_SGL_ENTS ((4096 - sizeof(struct af_alg_tsgl)) / \