crypto/lrw.c
72 static int setkey(struct crypto_skcipher *parent, const u8 *key,
73 unsigned int keylen)
74 {
75 struct priv *ctx = crypto_skcipher_ctx(parent);
76 struct crypto_skcipher *child = ctx->child;
77 int err, bsize = LRW_BLOCK_SIZE;
78 const u8 *tweak = key + keylen - bsize;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Smatch thinks that keylen is user controlled from zero to some upper
bound. How do we know it's >= LRW_BLOCK_SIZE (16)?
I find the crypto code sort of hard to follow... There are a bunch of
setkey pointers and they're sometimes called recursively. Is there
some trick or hints?
79 be128 tmp = { 0 };
80 int i;
81
82 crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
83 crypto_skcipher_set_flags(child,
crypto_skcipher_get_flags(parent) &
84 CRYPTO_TFM_REQ_MASK);
85 err = crypto_skcipher_setkey(child, key, keylen - bsize);
86 crypto_skcipher_set_flags(parent,
crypto_skcipher_get_flags(child) &
87 CRYPTO_TFM_RES_MASK);
88 if (err)
89 return err;
90
91 if (ctx->table)
92 gf128mul_free_64k(ctx->table);
93
94 /* initialize multiplication table for Key2 */
95 ctx->table = gf128mul_init_64k_bbe((be128 *)tweak);
96 if (!ctx->table)
97 return -ENOMEM;
98
99 /* initialize optimization table */
100 for (i = 0; i < 128; i++) {
101 setbit128_bbe(&tmp, i);
102 ctx->mulinc[i] = tmp;
103 gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
104 }
105
106 return 0;
107 }
regards,
dan carpenter
