wusb: Stop using the stack for sg crypto scratch space

Pointing an sg list at the stack is verboten and, with
CONFIG_VMAP_STACK=y, will malfunction.  Use kmalloc for the wusb
crypto stack space instead.

Untested -- I'm not entirely convinced that this hardware exists in
the wild.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/wusbcore/crypto.c b/drivers/usb/wusbcore/crypto.c
index 79b2b628066d81c5e5c6ceda10f707587c55b1c8..de089f3a82f3dc9767cac24a6702219df0d6514b 100644 (file)
--- a/drivers/usb/wusbcore/crypto.c
+++ b/drivers/usb/wusbcore/crypto.c
@@ -133,6 +133,13 @@ static void bytewise_xor(void *_bo, const void *_bi1, const void *_bi2,
                bo[itr] = bi1[itr] ^ bi2[itr];
 }
 
+/* Scratch space for MAC calculations. */
+struct wusb_mac_scratch {
+       struct aes_ccm_b0 b0;
+       struct aes_ccm_b1 b1;
+       struct aes_ccm_a ax;
+};
+
 /*
  * CC-MAC function WUSB1.0[6.5]
  *
@@ -197,16 +204,15 @@ static void bytewise_xor(void *_bo, const void *_bi1, const void *_bi2,
  *       what sg[4] is for. Maybe there is a smarter way to do this.
  */
 static int wusb_ccm_mac(struct crypto_skcipher *tfm_cbc,
-                       struct crypto_cipher *tfm_aes, void *mic,
+                       struct crypto_cipher *tfm_aes,
+                       struct wusb_mac_scratch *scratch,
+                       void *mic,
                        const struct aes_ccm_nonce *n,
                        const struct aes_ccm_label *a, const void *b,
                        size_t blen)
 {
        int result = 0;
        SKCIPHER_REQUEST_ON_STACK(req, tfm_cbc);
-       struct aes_ccm_b0 b0;
-       struct aes_ccm_b1 b1;
-       struct aes_ccm_a ax;
        struct scatterlist sg[4], sg_dst;
        void *dst_buf;
        size_t dst_size;
@@ -218,16 +224,17 @@ static int wusb_ccm_mac(struct crypto_skcipher *tfm_cbc,
         * These checks should be compile time optimized out
         * ensure @a fills b1's mac_header and following fields
         */
-       WARN_ON(sizeof(*a) != sizeof(b1) - sizeof(b1.la));
-       WARN_ON(sizeof(b0) != sizeof(struct aes_ccm_block));
-       WARN_ON(sizeof(b1) != sizeof(struct aes_ccm_block));
-       WARN_ON(sizeof(ax) != sizeof(struct aes_ccm_block));
+       WARN_ON(sizeof(*a) != sizeof(scratch->b1) - sizeof(scratch->b1.la));
+       WARN_ON(sizeof(scratch->b0) != sizeof(struct aes_ccm_block));
+       WARN_ON(sizeof(scratch->b1) != sizeof(struct aes_ccm_block));
+       WARN_ON(sizeof(scratch->ax) != sizeof(struct aes_ccm_block));
 
        result = -ENOMEM;
        zero_padding = blen % sizeof(struct aes_ccm_block);
        if (zero_padding)
                zero_padding = sizeof(struct aes_ccm_block) - zero_padding;
-       dst_size = blen + sizeof(b0) + sizeof(b1) + zero_padding;
+       dst_size = blen + sizeof(scratch->b0) + sizeof(scratch->b1) +
+               zero_padding;
        dst_buf = kzalloc(dst_size, GFP_KERNEL);
        if (!dst_buf)
                goto error_dst_buf;
@@ -235,9 +242,9 @@ static int wusb_ccm_mac(struct crypto_skcipher *tfm_cbc,
        memset(iv, 0, sizeof(iv));
 
        /* Setup B0 */
-       b0.flags = 0x59;        /* Format B0 */
-       b0.ccm_nonce = *n;
-       b0.lm = cpu_to_be16(0); /* WUSB1.0[6.5] sez l(m) is 0 */
+       scratch->b0.flags = 0x59;       /* Format B0 */
+       scratch->b0.ccm_nonce = *n;
+       scratch->b0.lm = cpu_to_be16(0);        /* WUSB1.0[6.5] sez l(m) is 0 */
 
        /* Setup B1
         *
@@ -246,12 +253,12 @@ static int wusb_ccm_mac(struct crypto_skcipher *tfm_cbc,
         * 14'--after clarification, it means to use A's contents
         * for MAC Header, EO, sec reserved and padding.
         */
-       b1.la = cpu_to_be16(blen + 14);
-       memcpy(&b1.mac_header, a, sizeof(*a));
+       scratch->b1.la = cpu_to_be16(blen + 14);
+       memcpy(&scratch->b1.mac_header, a, sizeof(*a));
 
        sg_init_table(sg, ARRAY_SIZE(sg));
-       sg_set_buf(&sg[0], &b0, sizeof(b0));
-       sg_set_buf(&sg[1], &b1, sizeof(b1));
+       sg_set_buf(&sg[0], &scratch->b0, sizeof(scratch->b0));
+       sg_set_buf(&sg[1], &scratch->b1, sizeof(scratch->b1));
        sg_set_buf(&sg[2], b, blen);
        /* 0 if well behaved :) */
        sg_set_buf(&sg[3], bzero, zero_padding);
@@ -276,11 +283,12 @@ static int wusb_ccm_mac(struct crypto_skcipher *tfm_cbc,
         * POS Crypto API: size is assumed to be AES's block size.
         * Thanks for documenting it -- tip taken from airo.c
         */
-       ax.flags = 0x01;                /* as per WUSB 1.0 spec */
-       ax.ccm_nonce = *n;
-       ax.counter = 0;
-       crypto_cipher_encrypt_one(tfm_aes, (void *)&ax, (void *)&ax);
-       bytewise_xor(mic, &ax, iv, 8);
+       scratch->ax.flags = 0x01;               /* as per WUSB 1.0 spec */
+       scratch->ax.ccm_nonce = *n;
+       scratch->ax.counter = 0;
+       crypto_cipher_encrypt_one(tfm_aes, (void *)&scratch->ax,
+                                 (void *)&scratch->ax);
+       bytewise_xor(mic, &scratch->ax, iv, 8);
        result = 8;
 error_cbc_crypt:
        kfree(dst_buf);
@@ -303,6 +311,7 @@ ssize_t wusb_prf(void *out, size_t out_size,
        struct aes_ccm_nonce n = *_n;
        struct crypto_skcipher *tfm_cbc;
        struct crypto_cipher *tfm_aes;
+       struct wusb_mac_scratch *scratch;
        u64 sfn = 0;
        __le64 sfn_le;
 
@@ -329,17 +338,23 @@ ssize_t wusb_prf(void *out, size_t out_size,
                printk(KERN_ERR "E: can't set AES key: %d\n", (int)result);
                goto error_setkey_aes;
        }
+       scratch = kmalloc(sizeof(*scratch), GFP_KERNEL);
+       if (!scratch)
+               goto error_alloc_scratch;
 
        for (bitr = 0; bitr < (len + 63) / 64; bitr++) {
                sfn_le = cpu_to_le64(sfn++);
                memcpy(&n.sfn, &sfn_le, sizeof(n.sfn)); /* n.sfn++... */
-               result = wusb_ccm_mac(tfm_cbc, tfm_aes, out + bytes,
+               result = wusb_ccm_mac(tfm_cbc, tfm_aes, scratch, out + bytes,
                                      &n, a, b, blen);
                if (result < 0)
                        goto error_ccm_mac;
                bytes += result;
        }
        result = bytes;
+
+       kfree(scratch);
+error_alloc_scratch:
 error_ccm_mac:
 error_setkey_aes:
        crypto_free_cipher(tfm_aes);