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NFS: Check lengths more thoroughly in NFS4 readdir XDR decode

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Check the bounds of length specifiers more thoroughly in the XDR decoding of
NFS4 readdir reply data.

Currently, if the server returns a bitmap or attr length that causes the
current decode point pointer to wrap, this could go undetected (consider a
small "negative" length on a 32-bit machine).

Also add a check into the main XDR decode handler to make sure that the amount
of data is a multiple of four bytes (as specified by RFC-1014).  This makes
sure that we can do u32* pointer subtraction in the NFS client without risking
an undefined result (the result is undefined if the pointers are not correctly
aligned with respect to one another).

Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
(cherry picked from 5861fddd64a7eaf7e8b1a9997455a24e7f688092 commit)
This commit is contained in:
David Howells 2006-08-24 15:44:19 -04:00 committed by Trond Myklebust
parent 3cedf13af9
commit e8896495bc
2 changed files with 22 additions and 10 deletions
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21
fs/nfs/nfs4xdr.c
View File

@ -3355,7 +3355,7 @@ static int decode_readdir(struct xdr_stream *xdr, struct rpc_rqst *req, struct n
struct kvec *iov = rcvbuf->head;
unsigned int nr, pglen = rcvbuf->page_len;
uint32_t *end, *entry, *p, *kaddr;
uint32_t len, attrlen;
uint32_t len, attrlen, xlen;
int hdrlen, recvd, status;
status = decode_op_hdr(xdr, OP_READDIR);
@ -3377,10 +3377,10 @@ static int decode_readdir(struct xdr_stream *xdr, struct rpc_rqst *req, struct n
BUG_ON(pglen + readdir->pgbase > PAGE_CACHE_SIZE);
kaddr = p = (uint32_t *) kmap_atomic(page, KM_USER0);
end = (uint32_t *) ((char *)p + pglen + readdir->pgbase);
end = p + ((pglen + readdir->pgbase) >> 2);
entry = p;
for (nr = 0; *p++; nr++) {
if (p + 3 > end)
if (end - p < 3)
goto short_pkt;
dprintk("cookie = %Lu, ", *((unsigned long long *)p));
p += 2; /* cookie */
@ -3389,18 +3389,19 @@ static int decode_readdir(struct xdr_stream *xdr, struct rpc_rqst *req, struct n
printk(KERN_WARNING "NFS: giant filename in readdir (len 0x%x)\n", len);
goto err_unmap;
}
xlen = XDR_QUADLEN(len);
if (end - p < xlen + 1)
goto short_pkt;
dprintk("filename = %*s\n", len, (char *)p);
p += XDR_QUADLEN(len);
if (p + 1 > end)
goto short_pkt;
p += xlen;
len = ntohl(*p++); /* bitmap length */
if (end - p < len + 1)
goto short_pkt;
p += len;
if (p + 1 > end)
goto short_pkt;
attrlen = XDR_QUADLEN(ntohl(*p++));
p += attrlen; /* attributes */
if (p + 2 > end)
if (end - p < attrlen + 2)
goto short_pkt;
p += attrlen; /* attributes */
entry = p;
}
if (!nr && (entry[0] != 0 || entry[1] == 0))

11
net/sunrpc/clnt.c
View File

@ -1181,6 +1181,17 @@ call_verify(struct rpc_task *task)
u32 *p = iov->iov_base, n;
int error = -EACCES;
if ((task->tk_rqstp->rq_rcv_buf.len & 3) != 0) {
/* RFC-1014 says that the representation of XDR data must be a
* multiple of four bytes
* - if it isn't pointer subtraction in the NFS client may give
* undefined results
*/
printk(KERN_WARNING
"call_verify: XDR representation not a multiple of"
" 4 bytes: 0x%x\n", task->tk_rqstp->rq_rcv_buf.len);
goto out_eio;
}
if ((len -= 3) < 0)
goto out_overflow;
p += 1; /* skip XID */