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SubjectRe: [PATCH] fs: nfsd: Fix three possible null-pointer dereferences
On Tue, Jul 30, 2019 at 07:03:39PM -0400, J. Bruce Fields wrote:
> Thanks! But I think actually the correct fix is just to remove the NULL
> checks entirely.

So, something like the following (untested).--b.

commit 7ce38d2d8a66
Author: J. Bruce Fields <bfields@redhat.com>
Date: Tue Jul 30 19:06:38 2019 -0400

nfsd: Remove unnecessary NULL checks

"cb" is never actually NULL in these functions.

On a quick skim of the history, they seem to have been there from the
beginning. I'm not sure if they originally served a purpose.

Reported-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index 397eb7820929..524111420b48 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -512,11 +512,9 @@ static int nfs4_xdr_dec_cb_recall(struct rpc_rqst *rqstp,
if (unlikely(status))
return status;

- if (cb != NULL) {
- status = decode_cb_sequence4res(xdr, cb);
- if (unlikely(status || cb->cb_seq_status))
- return status;
- }
+ status = decode_cb_sequence4res(xdr, cb);
+ if (unlikely(status || cb->cb_seq_status))
+ return status;

return decode_cb_op_status(xdr, OP_CB_RECALL, &cb->cb_status);
}
@@ -604,11 +602,10 @@ static int nfs4_xdr_dec_cb_layout(struct rpc_rqst *rqstp,
if (unlikely(status))
return status;

- if (cb) {
- status = decode_cb_sequence4res(xdr, cb);
- if (unlikely(status || cb->cb_seq_status))
- return status;
- }
+ status = decode_cb_sequence4res(xdr, cb);
+ if (unlikely(status || cb->cb_seq_status))
+ return status;
+
return decode_cb_op_status(xdr, OP_CB_LAYOUTRECALL, &cb->cb_status);
}
#endif /* CONFIG_NFSD_PNFS */
@@ -663,11 +660,10 @@ static int nfs4_xdr_dec_cb_notify_lock(struct rpc_rqst *rqstp,
if (unlikely(status))
return status;

- if (cb) {
- status = decode_cb_sequence4res(xdr, cb);
- if (unlikely(status || cb->cb_seq_status))
- return status;
- }
+ status = decode_cb_sequence4res(xdr, cb);
+ if (unlikely(status || cb->cb_seq_status))
+ return status;
+
return decode_cb_op_status(xdr, OP_CB_NOTIFY_LOCK, &cb->cb_status);
}

@@ -759,11 +755,10 @@ static int nfs4_xdr_dec_cb_offload(struct rpc_rqst *rqstp,
if (unlikely(status))
return status;

- if (cb) {
- status = decode_cb_sequence4res(xdr, cb);
- if (unlikely(status || cb->cb_seq_status))
- return status;
- }
+ status = decode_cb_sequence4res(xdr, cb);
+ if (unlikely(status || cb->cb_seq_status))
+ return status;
+
return decode_cb_op_status(xdr, OP_CB_OFFLOAD, &cb->cb_status);
}
/*
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