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authorLinus Torvalds <torvalds@linux-foundation.org>2017-04-27 13:39:19 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-04-27 13:39:19 -0700
commit8b5d11e4b095450e2f259d5f60ea18c13d2fe0a2 (patch)
tree8f33faf583528a703b3bf5bbf69ad0e7dc3ad94b /fs
parent19ac4474203863a8141663d73d5976fe25464bfd (diff)
parent13bf9fbff0e5e099e2b6f003a0ab8ae145436309 (diff)
Merge tag 'nfsd-4.11-3' of git://linux-nfs.org/~bfields/linux
Pull nfsd fixes from Bruce Fields: "Thanks to Ari Kauppi and Tuomas Haanpää at Synopsis for spotting bugs in our NFSv2/v3 xdr code that could crash the server or leak memory" * tag 'nfsd-4.11-3' of git://linux-nfs.org/~bfields/linux: nfsd: stricter decoding of write-like NFSv2/v3 ops nfsd4: minor NFSv2/v3 write decoding cleanup nfsd: check for oversized NFSv2/v3 arguments
Diffstat (limited to 'fs')
-rw-r--r--fs/nfsd/nfs3xdr.c13
-rw-r--r--fs/nfsd/nfssvc.c36
-rw-r--r--fs/nfsd/nfsxdr.c10
3 files changed, 51 insertions, 8 deletions
diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index dba2ff8eaa68..452334694a5d 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -358,6 +358,8 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
{
unsigned int len, v, hdr, dlen;
u32 max_blocksize = svc_max_payload(rqstp);
+ struct kvec *head = rqstp->rq_arg.head;
+ struct kvec *tail = rqstp->rq_arg.tail;
p = decode_fh(p, &args->fh);
if (!p)
@@ -367,6 +369,8 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
args->count = ntohl(*p++);
args->stable = ntohl(*p++);
len = args->len = ntohl(*p++);
+ if ((void *)p > head->iov_base + head->iov_len)
+ return 0;
/*
* The count must equal the amount of data passed.
*/
@@ -377,9 +381,8 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
* Check to make sure that we got the right number of
* bytes.
*/
- hdr = (void*)p - rqstp->rq_arg.head[0].iov_base;
- dlen = rqstp->rq_arg.head[0].iov_len + rqstp->rq_arg.page_len
- + rqstp->rq_arg.tail[0].iov_len - hdr;
+ hdr = (void*)p - head->iov_base;
+ dlen = head->iov_len + rqstp->rq_arg.page_len + tail->iov_len - hdr;
/*
* Round the length of the data which was specified up to
* the next multiple of XDR units and then compare that
@@ -396,7 +399,7 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
len = args->len = max_blocksize;
}
rqstp->rq_vec[0].iov_base = (void*)p;
- rqstp->rq_vec[0].iov_len = rqstp->rq_arg.head[0].iov_len - hdr;
+ rqstp->rq_vec[0].iov_len = head->iov_len - hdr;
v = 0;
while (len > rqstp->rq_vec[v].iov_len) {
len -= rqstp->rq_vec[v].iov_len;
@@ -471,6 +474,8 @@ nfs3svc_decode_symlinkargs(struct svc_rqst *rqstp, __be32 *p,
/* first copy and check from the first page */
old = (char*)p;
vec = &rqstp->rq_arg.head[0];
+ if ((void *)old > vec->iov_base + vec->iov_len)
+ return 0;
avail = vec->iov_len - (old - (char*)vec->iov_base);
while (len && avail && *old) {
*new++ = *old++;
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index 31e1f9593457..59979f0bbd4b 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -747,6 +747,37 @@ static __be32 map_new_errors(u32 vers, __be32 nfserr)
return nfserr;
}
+/*
+ * A write procedure can have a large argument, and a read procedure can
+ * have a large reply, but no NFSv2 or NFSv3 procedure has argument and
+ * reply that can both be larger than a page. The xdr code has taken
+ * advantage of this assumption to be a sloppy about bounds checking in
+ * some cases. Pending a rewrite of the NFSv2/v3 xdr code to fix that
+ * problem, we enforce these assumptions here:
+ */
+static bool nfs_request_too_big(struct svc_rqst *rqstp,
+ struct svc_procedure *proc)
+{
+ /*
+ * The ACL code has more careful bounds-checking and is not
+ * susceptible to this problem:
+ */
+ if (rqstp->rq_prog != NFS_PROGRAM)
+ return false;
+ /*
+ * Ditto NFSv4 (which can in theory have argument and reply both
+ * more than a page):
+ */
+ if (rqstp->rq_vers >= 4)
+ return false;
+ /* The reply will be small, we're OK: */
+ if (proc->pc_xdrressize > 0 &&
+ proc->pc_xdrressize < XDR_QUADLEN(PAGE_SIZE))
+ return false;
+
+ return rqstp->rq_arg.len > PAGE_SIZE;
+}
+
int
nfsd_dispatch(struct svc_rqst *rqstp, __be32 *statp)
{
@@ -759,6 +790,11 @@ nfsd_dispatch(struct svc_rqst *rqstp, __be32 *statp)
rqstp->rq_vers, rqstp->rq_proc);
proc = rqstp->rq_procinfo;
+ if (nfs_request_too_big(rqstp, proc)) {
+ dprintk("nfsd: NFSv%d argument too large\n", rqstp->rq_vers);
+ *statp = rpc_garbage_args;
+ return 1;
+ }
/*
* Give the xdr decoder a chance to change this if it wants
* (necessary in the NFSv4.0 compound case)
diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
index 41b468a6a90f..de07ff625777 100644
--- a/fs/nfsd/nfsxdr.c
+++ b/fs/nfsd/nfsxdr.c
@@ -280,6 +280,7 @@ nfssvc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
struct nfsd_writeargs *args)
{
unsigned int len, hdr, dlen;
+ struct kvec *head = rqstp->rq_arg.head;
int v;
p = decode_fh(p, &args->fh);
@@ -300,9 +301,10 @@ nfssvc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
* Check to make sure that we got the right number of
* bytes.
*/
- hdr = (void*)p - rqstp->rq_arg.head[0].iov_base;
- dlen = rqstp->rq_arg.head[0].iov_len + rqstp->rq_arg.page_len
- - hdr;
+ hdr = (void*)p - head->iov_base;
+ if (hdr > head->iov_len)
+ return 0;
+ dlen = head->iov_len + rqstp->rq_arg.page_len - hdr;
/*
* Round the length of the data which was specified up to
@@ -316,7 +318,7 @@ nfssvc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
return 0;
rqstp->rq_vec[0].iov_base = (void*)p;
- rqstp->rq_vec[0].iov_len = rqstp->rq_arg.head[0].iov_len - hdr;
+ rqstp->rq_vec[0].iov_len = head->iov_len - hdr;
v = 0;
while (len > rqstp->rq_vec[v].iov_len) {
len -= rqstp->rq_vec[v].iov_len;