sunrpc: fix 4 more call sites that were using stack memory with a scatterlist

While trying to reproduce a reported kernel panic on arm64, I discovered
that AUTH_GSS basically doesn't work at all with older enctypes on arm64
systems with CONFIG_VMAP_STACK enabled.  It turns out there still a few
places using stack memory with scatterlists, causing krb5_encrypt() and
krb5_decrypt() to produce incorrect results (or a BUG if CONFIG_DEBUG_SG
is enabled).

Tested with cthon on v4.0/v4.1/v4.2 with krb5/krb5i/krb5p using
des3-cbc-sha1 and arcfour-hmac-md5.

Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/net/sunrpc/auth_gss/gss_krb5_seqnum.c b/net/sunrpc/auth_gss/gss_krb5_seqnum.c
index fb6656295204cf6d2fca0451b8ba93a3e5fac057..507105127095a24ca89d49b12118d3e12ce85726 100644 (file)
--- a/net/sunrpc/auth_gss/gss_krb5_seqnum.c
+++ b/net/sunrpc/auth_gss/gss_krb5_seqnum.c
@@ -44,7 +44,7 @@ krb5_make_rc4_seq_num(struct krb5_ctx *kctx, int direction, s32 seqnum,
                      unsigned char *cksum, unsigned char *buf)
 {
        struct crypto_sync_skcipher *cipher;
-       unsigned char plain[8];
+       unsigned char *plain;
        s32 code;
 
        dprintk("RPC:       %s:\n", __func__);
@@ -52,6 +52,10 @@ krb5_make_rc4_seq_num(struct krb5_ctx *kctx, int direction, s32 seqnum,
        if (IS_ERR(cipher))
                return PTR_ERR(cipher);
 
+       plain = kmalloc(8, GFP_NOFS);
+       if (!plain)
+               return -ENOMEM;
+
        plain[0] = (unsigned char) ((seqnum >> 24) & 0xff);
        plain[1] = (unsigned char) ((seqnum >> 16) & 0xff);
        plain[2] = (unsigned char) ((seqnum >> 8) & 0xff);
@@ -67,6 +71,7 @@ krb5_make_rc4_seq_num(struct krb5_ctx *kctx, int direction, s32 seqnum,
 
        code = krb5_encrypt(cipher, cksum, plain, buf, 8);
 out:
+       kfree(plain);
        crypto_free_sync_skcipher(cipher);
        return code;
 }
@@ -77,12 +82,17 @@ krb5_make_seq_num(struct krb5_ctx *kctx,
                u32 seqnum,
                unsigned char *cksum, unsigned char *buf)
 {
-       unsigned char plain[8];
+       unsigned char *plain;
+       s32 code;
 
        if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC)
                return krb5_make_rc4_seq_num(kctx, direction, seqnum,
                                             cksum, buf);
 
+       plain = kmalloc(8, GFP_NOFS);
+       if (!plain)
+               return -ENOMEM;
+
        plain[0] = (unsigned char) (seqnum & 0xff);
        plain[1] = (unsigned char) ((seqnum >> 8) & 0xff);
        plain[2] = (unsigned char) ((seqnum >> 16) & 0xff);
@@ -93,7 +103,9 @@ krb5_make_seq_num(struct krb5_ctx *kctx,
        plain[6] = direction;
        plain[7] = direction;
 
-       return krb5_encrypt(key, cksum, plain, buf, 8);
+       code = krb5_encrypt(key, cksum, plain, buf, 8);
+       kfree(plain);
+       return code;
 }
 
 static s32
@@ -101,7 +113,7 @@ krb5_get_rc4_seq_num(struct krb5_ctx *kctx, unsigned char *cksum,
                     unsigned char *buf, int *direction, s32 *seqnum)
 {
        struct crypto_sync_skcipher *cipher;
-       unsigned char plain[8];
+       unsigned char *plain;
        s32 code;
 
        dprintk("RPC:       %s:\n", __func__);
@@ -113,20 +125,28 @@ krb5_get_rc4_seq_num(struct krb5_ctx *kctx, unsigned char *cksum,
        if (code)
                goto out;
 
+       plain = kmalloc(8, GFP_NOFS);
+       if (!plain) {
+               code = -ENOMEM;
+               goto out;
+       }
+
        code = krb5_decrypt(cipher, cksum, buf, plain, 8);
        if (code)
-               goto out;
+               goto out_plain;
 
        if ((plain[4] != plain[5]) || (plain[4] != plain[6])
                                   || (plain[4] != plain[7])) {
                code = (s32)KG_BAD_SEQ;
-               goto out;
+               goto out_plain;
        }
 
        *direction = plain[4];
 
        *seqnum = ((plain[0] << 24) | (plain[1] << 16) |
                                        (plain[2] << 8) | (plain[3]));
+out_plain:
+       kfree(plain);
 out:
        crypto_free_sync_skcipher(cipher);
        return code;
@@ -139,7 +159,7 @@ krb5_get_seq_num(struct krb5_ctx *kctx,
               int *direction, u32 *seqnum)
 {
        s32 code;
-       unsigned char plain[8];
+       unsigned char *plain;
        struct crypto_sync_skcipher *key = kctx->seq;
 
        dprintk("RPC:       krb5_get_seq_num:\n");
@@ -147,18 +167,25 @@ krb5_get_seq_num(struct krb5_ctx *kctx,
        if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC)
                return krb5_get_rc4_seq_num(kctx, cksum, buf,
                                            direction, seqnum);
+       plain = kmalloc(8, GFP_NOFS);
+       if (!plain)
+               return -ENOMEM;
 
        if ((code = krb5_decrypt(key, cksum, buf, plain, 8)))
-               return code;
+               goto out;
 
        if ((plain[4] != plain[5]) || (plain[4] != plain[6]) ||
-           (plain[4] != plain[7]))
-               return (s32)KG_BAD_SEQ;
+           (plain[4] != plain[7])) {
+               code = (s32)KG_BAD_SEQ;
+               goto out;
+       }
 
        *direction = plain[4];
 
        *seqnum = ((plain[0]) |
                   (plain[1] << 8) | (plain[2] << 16) | (plain[3] << 24));
 
-       return 0;
+out:
+       kfree(plain);
+       return code;
 }