207 lines
6.3 KiB
Diff
207 lines
6.3 KiB
Diff
From: David Howells <dhowells@redhat.com>
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Date: Thu, 15 Jun 2017 00:12:24 +0100
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Subject: rxrpc: Fix several cases where a padded len isn't checked in ticket
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decode
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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Origin: https://git.kernel.org/linus/5f2f97656ada8d811d3c1bef503ced266fcd53a0
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Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2017-7482
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This fixes CVE-2017-7482.
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When a kerberos 5 ticket is being decoded so that it can be loaded into an
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rxrpc-type key, there are several places in which the length of a
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variable-length field is checked to make sure that it's not going to
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overrun the available data - but the data is padded to the nearest
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four-byte boundary and the code doesn't check for this extra. This could
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lead to the size-remaining variable wrapping and the data pointer going
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over the end of the buffer.
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Fix this by making the various variable-length data checks use the padded
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length.
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Reported-by: 石磊 <shilei-c@360.cn>
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Signed-off-by: David Howells <dhowells@redhat.com>
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Reviewed-by: Marc Dionne <marc.c.dionne@auristor.com>
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Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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net/rxrpc/key.c | 64 ++++++++++++++++++++++++++++++---------------------------
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1 file changed, 34 insertions(+), 30 deletions(-)
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diff --git a/net/rxrpc/key.c b/net/rxrpc/key.c
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index 0a4e28477ad9..54369225766e 100644
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--- a/net/rxrpc/key.c
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+++ b/net/rxrpc/key.c
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@@ -217,7 +217,7 @@ static int rxrpc_krb5_decode_principal(struct krb5_principal *princ,
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unsigned int *_toklen)
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{
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const __be32 *xdr = *_xdr;
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- unsigned int toklen = *_toklen, n_parts, loop, tmp;
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+ unsigned int toklen = *_toklen, n_parts, loop, tmp, paddedlen;
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/* there must be at least one name, and at least #names+1 length
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* words */
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@@ -247,16 +247,16 @@ static int rxrpc_krb5_decode_principal(struct krb5_principal *princ,
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toklen -= 4;
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if (tmp <= 0 || tmp > AFSTOKEN_STRING_MAX)
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return -EINVAL;
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- if (tmp > toklen)
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+ paddedlen = (tmp + 3) & ~3;
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+ if (paddedlen > toklen)
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return -EINVAL;
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princ->name_parts[loop] = kmalloc(tmp + 1, GFP_KERNEL);
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if (!princ->name_parts[loop])
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return -ENOMEM;
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memcpy(princ->name_parts[loop], xdr, tmp);
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princ->name_parts[loop][tmp] = 0;
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- tmp = (tmp + 3) & ~3;
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- toklen -= tmp;
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- xdr += tmp >> 2;
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+ toklen -= paddedlen;
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+ xdr += paddedlen >> 2;
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}
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if (toklen < 4)
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@@ -265,16 +265,16 @@ static int rxrpc_krb5_decode_principal(struct krb5_principal *princ,
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toklen -= 4;
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if (tmp <= 0 || tmp > AFSTOKEN_K5_REALM_MAX)
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return -EINVAL;
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- if (tmp > toklen)
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+ paddedlen = (tmp + 3) & ~3;
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+ if (paddedlen > toklen)
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return -EINVAL;
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princ->realm = kmalloc(tmp + 1, GFP_KERNEL);
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if (!princ->realm)
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return -ENOMEM;
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memcpy(princ->realm, xdr, tmp);
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princ->realm[tmp] = 0;
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- tmp = (tmp + 3) & ~3;
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- toklen -= tmp;
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- xdr += tmp >> 2;
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+ toklen -= paddedlen;
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+ xdr += paddedlen >> 2;
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_debug("%s/...@%s", princ->name_parts[0], princ->realm);
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@@ -293,7 +293,7 @@ static int rxrpc_krb5_decode_tagged_data(struct krb5_tagged_data *td,
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unsigned int *_toklen)
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{
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const __be32 *xdr = *_xdr;
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- unsigned int toklen = *_toklen, len;
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+ unsigned int toklen = *_toklen, len, paddedlen;
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/* there must be at least one tag and one length word */
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if (toklen <= 8)
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@@ -307,15 +307,17 @@ static int rxrpc_krb5_decode_tagged_data(struct krb5_tagged_data *td,
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toklen -= 8;
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if (len > max_data_size)
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return -EINVAL;
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+ paddedlen = (len + 3) & ~3;
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+ if (paddedlen > toklen)
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+ return -EINVAL;
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td->data_len = len;
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if (len > 0) {
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td->data = kmemdup(xdr, len, GFP_KERNEL);
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if (!td->data)
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return -ENOMEM;
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- len = (len + 3) & ~3;
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- toklen -= len;
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- xdr += len >> 2;
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+ toklen -= paddedlen;
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+ xdr += paddedlen >> 2;
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}
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_debug("tag %x len %x", td->tag, td->data_len);
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@@ -387,7 +389,7 @@ static int rxrpc_krb5_decode_ticket(u8 **_ticket, u16 *_tktlen,
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const __be32 **_xdr, unsigned int *_toklen)
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{
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const __be32 *xdr = *_xdr;
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- unsigned int toklen = *_toklen, len;
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+ unsigned int toklen = *_toklen, len, paddedlen;
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/* there must be at least one length word */
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if (toklen <= 4)
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@@ -399,6 +401,9 @@ static int rxrpc_krb5_decode_ticket(u8 **_ticket, u16 *_tktlen,
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toklen -= 4;
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if (len > AFSTOKEN_K5_TIX_MAX)
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return -EINVAL;
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+ paddedlen = (len + 3) & ~3;
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+ if (paddedlen > toklen)
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+ return -EINVAL;
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*_tktlen = len;
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_debug("ticket len %u", len);
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@@ -407,9 +412,8 @@ static int rxrpc_krb5_decode_ticket(u8 **_ticket, u16 *_tktlen,
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*_ticket = kmemdup(xdr, len, GFP_KERNEL);
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if (!*_ticket)
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return -ENOMEM;
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- len = (len + 3) & ~3;
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- toklen -= len;
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- xdr += len >> 2;
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+ toklen -= paddedlen;
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+ xdr += paddedlen >> 2;
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}
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*_xdr = xdr;
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@@ -552,7 +556,7 @@ static int rxrpc_preparse_xdr(struct key_preparsed_payload *prep)
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{
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const __be32 *xdr = prep->data, *token;
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const char *cp;
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- unsigned int len, tmp, loop, ntoken, toklen, sec_ix;
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+ unsigned int len, paddedlen, loop, ntoken, toklen, sec_ix;
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size_t datalen = prep->datalen;
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int ret;
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@@ -578,22 +582,21 @@ static int rxrpc_preparse_xdr(struct key_preparsed_payload *prep)
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if (len < 1 || len > AFSTOKEN_CELL_MAX)
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goto not_xdr;
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datalen -= 4;
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- tmp = (len + 3) & ~3;
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- if (tmp > datalen)
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+ paddedlen = (len + 3) & ~3;
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+ if (paddedlen > datalen)
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goto not_xdr;
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cp = (const char *) xdr;
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for (loop = 0; loop < len; loop++)
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if (!isprint(cp[loop]))
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goto not_xdr;
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- if (len < tmp)
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- for (; loop < tmp; loop++)
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- if (cp[loop])
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- goto not_xdr;
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+ for (; loop < paddedlen; loop++)
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+ if (cp[loop])
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+ goto not_xdr;
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_debug("cellname: [%u/%u] '%*.*s'",
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- len, tmp, len, len, (const char *) xdr);
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- datalen -= tmp;
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- xdr += tmp >> 2;
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+ len, paddedlen, len, len, (const char *) xdr);
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+ datalen -= paddedlen;
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+ xdr += paddedlen >> 2;
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/* get the token count */
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if (datalen < 12)
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@@ -614,10 +617,11 @@ static int rxrpc_preparse_xdr(struct key_preparsed_payload *prep)
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sec_ix = ntohl(*xdr);
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datalen -= 4;
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_debug("token: [%x/%zx] %x", toklen, datalen, sec_ix);
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- if (toklen < 20 || toklen > datalen)
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+ paddedlen = (toklen + 3) & ~3;
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+ if (toklen < 20 || toklen > datalen || paddedlen > datalen)
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goto not_xdr;
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- datalen -= (toklen + 3) & ~3;
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- xdr += (toklen + 3) >> 2;
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+ datalen -= paddedlen;
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+ xdr += paddedlen >> 2;
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} while (--loop > 0);
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--
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2.11.0
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