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svcrpc: fix potential GSSX_ACCEPT_SEC_CONTEXT decoding failures 

In an environment where the KDC is running Active Directory, the
exported composite name field returned in the context could be large
enough to span a page boundary.  Attaching a scratch buffer to the
decoding xdr_stream helps deal with those cases.

The case where we saw this was actually due to behavior that's been
fixed in newer gss-proxy versions, but we're fixing it here too.

Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Cc: stable@vger.kernel.org
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
wifi-calibration
Scott Mayhew 2015-04-28 16:29:53 -04:00 committed by J. Bruce Fields
parent 8287f009bd
commit 9507271d96
1 changed files with 16 additions and 7 deletions
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23
net/sunrpc/auth_gss/gss_rpc_xdr.c
View File

@ -793,20 +793,26 @@ int gssx_dec_accept_sec_context(struct rpc_rqst *rqstp,
{
u32 value_follows;
int err;
struct page *scratch;
scratch = alloc_page(GFP_KERNEL);
if (!scratch)
return -ENOMEM;
xdr_set_scratch_buffer(xdr, page_address(scratch), PAGE_SIZE);
/* res->status */
err = gssx_dec_status(xdr, &res->status);
if (err)
return err;
goto out_free;
/* res->context_handle */
err = gssx_dec_bool(xdr, &value_follows);
if (err)
return err;
goto out_free;
if (value_follows) {
err = gssx_dec_ctx(xdr, res->context_handle);
if (err)
return err;
goto out_free;
} else {
res->context_handle = NULL;
}
@ -814,11 +820,11 @@ int gssx_dec_accept_sec_context(struct rpc_rqst *rqstp,
/* res->output_token */
err = gssx_dec_bool(xdr, &value_follows);
if (err)
return err;
goto out_free;
if (value_follows) {
err = gssx_dec_buffer(xdr, res->output_token);
if (err)
return err;
goto out_free;
} else {
res->output_token = NULL;
}
@ -826,14 +832,17 @@ int gssx_dec_accept_sec_context(struct rpc_rqst *rqstp,
/* res->delegated_cred_handle */
err = gssx_dec_bool(xdr, &value_follows);
if (err)
return err;
goto out_free;
if (value_follows) {
/* we do not support upcall servers sending this data. */
return -EINVAL;
err = -EINVAL;
goto out_free;
}
/* res->options */
err = gssx_dec_option_array(xdr, &res->options);
out_free:
__free_page(scratch);
return err;
}