> > + if (!*(rqstp->rq_next_page))
> > + return 0;
>
> Why the extra parentheses? "->" is at the highest precedence level for C.
I've been doing this stuff enough years, you'd think I'd have bothered
to memorize the C operator precedence table by now.
Anyway, this change is actually unrelated and not entirely necessary;
dropped.
> i.e. either keep it simple (like the v2 code) or make it tidy (with head
> and tail), but not half-and-half??
What the heck, let's go all out.
You only live once!
--b.
commit db44bac41bbf
Author: J. Bruce Fields <bfields@xxxxxxxxxx>
Date: Tue Apr 25 16:21:34 2017 -0400
nfsd4: minor NFSv2/v3 write decoding cleanup
Use a couple shortcuts that will simplify a following bugfix.
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index dba2ff8eaa68..d18cfddbe115 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)
@@ -377,9 +379,8 @@ 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 +397,7 @@ 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;
diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
index 41b468a6a90f..59bd88a23a3d 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 +301,8 @@ 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;
+ dlen = head->iov_len + rqstp->rq_arg.page_len - hdr;
/*
* Round the length of the data which was specified up to
@@ -316,7 +316,7 @@ 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;
commit 13bf9fbff0e5
Author: J. Bruce Fields <bfields@xxxxxxxxxx>
Date: Fri Apr 21 15:26:30 2017 -0400
nfsd: stricter decoding of write-like NFSv2/v3 ops
The NFSv2/v3 code does not systematically check whether we decode past
the end of the buffer. This generally appears to be harmless, but there
are a few places where we do arithmetic on the pointers involved and
don't account for the possibility that a length could be negative. Add
checks to catch these.
Reported-by: Tuomas Haanpää <thaan@xxxxxxxxxxxx>
Reported-by: Ari Kauppi <ari@xxxxxxxxxxxx>
Reviewed-by: NeilBrown <neilb@xxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index d18cfddbe115..452334694a5d 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -369,6 +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.
*/
@@ -472,6 +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/nfsxdr.c b/fs/nfsd/nfsxdr.c
index 59bd88a23a3d..de07ff625777 100644
--- a/fs/nfsd/nfsxdr.c
+++ b/fs/nfsd/nfsxdr.c
@@ -302,6 +302,8 @@ nfssvc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
* bytes.
*/
hdr = (void*)p - head->iov_base;
+ if (hdr > head->iov_len)
+ return 0;
dlen = head->iov_len + rqstp->rq_arg.page_len - hdr;
/*
--
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