ACK.--b.
On Tue, Feb 19, 2019 at 02:36:27PM -0500, Scott Mayhew wrote:
> (cherry picked from commit e7afe6c1d486b516ed586dcc10b3e7e3e85a9c2b)
>
> 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@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
>
> Conflicts:
> net/sunrpc/auth_gss/gss_krb5_seqnum.c
> ---
> net/sunrpc/auth_gss/gss_krb5_seqnum.c | 49 +++++++++++++++++++++++++++--------
> 1 file changed, 38 insertions(+), 11 deletions(-)
>
> diff --git a/net/sunrpc/auth_gss/gss_krb5_seqnum.c b/net/sunrpc/auth_gss/gss_krb5_seqnum.c
> index c8b9082..2d2ed67 100644
> --- a/net/sunrpc/auth_gss/gss_krb5_seqnum.c
> +++ b/net/sunrpc/auth_gss/gss_krb5_seqnum.c
> @@ -44,7 +44,7 @@
> unsigned char *cksum, unsigned char *buf)
> {
> struct crypto_skcipher *cipher;
> - unsigned char plain[8];
> + unsigned char *plain;
> s32 code;
>
> dprintk("RPC: %s:\n", __func__);
> @@ -53,6 +53,10 @@
> 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);
> @@ -69,6 +73,7 @@
> code = krb5_encrypt(cipher, cksum, plain, buf, 8);
> out:
> crypto_free_skcipher(cipher);
> + kfree(plain);
> return code;
> }
> s32
> @@ -78,12 +83,17 @@
> 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);
> @@ -94,7 +104,9 @@
> 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
> @@ -102,7 +114,7 @@
> unsigned char *buf, int *direction, s32 *seqnum)
> {
> struct crypto_skcipher *cipher;
> - unsigned char plain[8];
> + unsigned char *plain;
> s32 code;
>
> dprintk("RPC: %s:\n", __func__);
> @@ -115,20 +127,28 @@
> 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_skcipher(cipher);
> return code;
> @@ -141,26 +161,33 @@
> int *direction, u32 *seqnum)
> {
> s32 code;
> - unsigned char plain[8];
> struct crypto_skcipher *key = kctx->seq;
> + unsigned char *plain;
>
> dprintk("RPC: krb5_get_seq_num:\n");
>
> 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;
> }
> --
> 1.8.3.1
>
