Currently the kernel will issue the following warnings:

fs/nfs/callback_xdr.c: In function 'nfs4_callback_compound':
fs/nfs/callback_xdr.c:404: warning: 'hdr_arg.taglen' may be used uninitialized in this function
fs/nfs/callback_xdr.c:404: warning: 'hdr_arg.tag' may be used uninitialized in this function
fs/nfs/callback_xdr.c:404: warning: 'hdr_arg.nops' may be used uninitialized in this function

It seems that call chain look something like:
nfs4_callback_compound()
-> decode_compound_hdr_arg()
-> decode_string() which may fail and return NFS4ERR_RESOURCE.
Which decode_compound_hdr_arg() passes on. Unfortunately
nfs4_callback_compound() doesn't check this status and cheerfully uses
hdr_arg which is basically stack garbage. The same problem seems to
apply to encode_compound_hdr_res().

Check the return values, and explictly tell gcc to silence that warning.

Signed-off-by: Tony Breeds
---
fs/nfs/callback_xdr.c | 10 +++++++---
1 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/nfs/callback_xdr.c b/fs/nfs/callback_xdr.c
index 13619d2..d26af3e 100644
--- a/fs/nfs/callback_xdr.c
+++ b/fs/nfs/callback_xdr.c
@@ -401,7 +401,7 @@ static __be32 process_op(struct svc_rqst *rqstp,
*/
static __be32 nfs4_callback_compound(struct svc_rqst *rqstp, void *argp, void *resp)
{
- struct cb_compound_hdr_arg hdr_arg;
+ struct cb_compound_hdr_arg uninitialized_var(hdr_arg);
struct cb_compound_hdr_res hdr_res;
struct xdr_stream xdr_in, xdr_out;
__be32 *p;
@@ -415,11 +415,15 @@ static __be32 nfs4_callback_compound(struct svc_rqst *rqstp, void *argp, void *r
p = (__be32*)((char *)rqstp->rq_res.head[0].iov_base + rqstp->rq_res.head[0].iov_len);
xdr_init_encode(&xdr_out, &rqstp->rq_res, p);

- decode_compound_hdr_arg(&xdr_in, &hdr_arg);
+ status = decode_compound_hdr_arg(&xdr_in, &hdr_arg);
+ if (unlikely(status != 0))
+ return status;
hdr_res.taglen = hdr_arg.taglen;
hdr_res.tag = hdr_arg.tag;
hdr_res.nops = NULL;
- encode_compound_hdr_res(&xdr_out, &hdr_res);
+ status = encode_compound_hdr_res(&xdr_out, &hdr_res);
+ if (unlikely(status != 0))
+ return status;

for (; {
status = process_op(rqstp, &xdr_in, argp, &xdr_out, resp);
--
1.5.5.1



Yours Tony

linux.conf.au http://www.marchsouth.org/
Jan 19 - 24 2009 The Australian Linux Technical Conference!

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/