* [PATCH] fs: nfsd: Fix three possible null-pointer dereferences
@ 2019-07-24 8:28 Jia-Ju Bai
2019-07-30 23:03 ` J. Bruce Fields
0 siblings, 1 reply; 3+ messages in thread
From: Jia-Ju Bai @ 2019-07-24 8:28 UTC (permalink / raw)
To: bfields, chuck.lever; +Cc: linux-nfs, linux-kernel, Jia-Ju Bai
In nfs4_xdr_dec_cb_recall(), nfs4_xdr_dec_cb_layout() and
nfs4_xdr_dec_cb_notify_lock(), there is an if statement to check whether
cb is NULL.
When cb is NULL, the three functions all call:
decode_cb_op_status(..., &cb->cb_status);
Thus, possible null-pointer dereferences may occur.
To fix these possible bugs, -EINVAL is returned when cb is NULL.
These bugs are found by a static analysis tool STCheck written by us.
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
---
fs/nfsd/nfs4callback.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index 397eb7820929..55949a158b6b 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -516,7 +516,8 @@ static int nfs4_xdr_dec_cb_recall(struct rpc_rqst *rqstp,
status = decode_cb_sequence4res(xdr, cb);
if (unlikely(status || cb->cb_seq_status))
return status;
- }
+ } else
+ return -EINVAL;
return decode_cb_op_status(xdr, OP_CB_RECALL, &cb->cb_status);
}
@@ -608,7 +609,9 @@ static int nfs4_xdr_dec_cb_layout(struct rpc_rqst *rqstp,
status = decode_cb_sequence4res(xdr, cb);
if (unlikely(status || cb->cb_seq_status))
return status;
- }
+ } else
+ return -EINVAL;
+
return decode_cb_op_status(xdr, OP_CB_LAYOUTRECALL, &cb->cb_status);
}
#endif /* CONFIG_NFSD_PNFS */
@@ -667,7 +670,9 @@ static int nfs4_xdr_dec_cb_notify_lock(struct rpc_rqst *rqstp,
status = decode_cb_sequence4res(xdr, cb);
if (unlikely(status || cb->cb_seq_status))
return status;
- }
+ } else
+ return -EINVAL;
+
return decode_cb_op_status(xdr, OP_CB_NOTIFY_LOCK, &cb->cb_status);
}
--
2.17.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] fs: nfsd: Fix three possible null-pointer dereferences
2019-07-24 8:28 [PATCH] fs: nfsd: Fix three possible null-pointer dereferences Jia-Ju Bai
@ 2019-07-30 23:03 ` J. Bruce Fields
2019-07-30 23:08 ` J. Bruce Fields
0 siblings, 1 reply; 3+ messages in thread
From: J. Bruce Fields @ 2019-07-30 23:03 UTC (permalink / raw)
To: Jia-Ju Bai; +Cc: chuck.lever, linux-nfs, linux-kernel
On Wed, Jul 24, 2019 at 04:28:03PM +0800, Jia-Ju Bai wrote:
> In nfs4_xdr_dec_cb_recall(), nfs4_xdr_dec_cb_layout() and
> nfs4_xdr_dec_cb_notify_lock(), there is an if statement to check whether
> cb is NULL.
>
> When cb is NULL, the three functions all call:
> decode_cb_op_status(..., &cb->cb_status);
>
> Thus, possible null-pointer dereferences may occur.
>
> To fix these possible bugs, -EINVAL is returned when cb is NULL.
>
> These bugs are found by a static analysis tool STCheck written by us.
Thanks! But I think actually the correct fix is just to remove the NULL
checks entirely.
--b.
>
> Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
> ---
> fs/nfsd/nfs4callback.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
> index 397eb7820929..55949a158b6b 100644
> --- a/fs/nfsd/nfs4callback.c
> +++ b/fs/nfsd/nfs4callback.c
> @@ -516,7 +516,8 @@ static int nfs4_xdr_dec_cb_recall(struct rpc_rqst *rqstp,
> status = decode_cb_sequence4res(xdr, cb);
> if (unlikely(status || cb->cb_seq_status))
> return status;
> - }
> + } else
> + return -EINVAL;
>
> return decode_cb_op_status(xdr, OP_CB_RECALL, &cb->cb_status);
> }
> @@ -608,7 +609,9 @@ static int nfs4_xdr_dec_cb_layout(struct rpc_rqst *rqstp,
> status = decode_cb_sequence4res(xdr, cb);
> if (unlikely(status || cb->cb_seq_status))
> return status;
> - }
> + } else
> + return -EINVAL;
> +
> return decode_cb_op_status(xdr, OP_CB_LAYOUTRECALL, &cb->cb_status);
> }
> #endif /* CONFIG_NFSD_PNFS */
> @@ -667,7 +670,9 @@ static int nfs4_xdr_dec_cb_notify_lock(struct rpc_rqst *rqstp,
> status = decode_cb_sequence4res(xdr, cb);
> if (unlikely(status || cb->cb_seq_status))
> return status;
> - }
> + } else
> + return -EINVAL;
> +
> return decode_cb_op_status(xdr, OP_CB_NOTIFY_LOCK, &cb->cb_status);
> }
>
> --
> 2.17.0
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] fs: nfsd: Fix three possible null-pointer dereferences
2019-07-30 23:03 ` J. Bruce Fields
@ 2019-07-30 23:08 ` J. Bruce Fields
0 siblings, 0 replies; 3+ messages in thread
From: J. Bruce Fields @ 2019-07-30 23:08 UTC (permalink / raw)
To: Jia-Ju Bai; +Cc: chuck.lever, linux-nfs, linux-kernel
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);
}
/*
^ permalink raw reply related [flat|nested] 3+ messages in thread
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2019-07-24 8:28 [PATCH] fs: nfsd: Fix three possible null-pointer dereferences Jia-Ju Bai
2019-07-30 23:03 ` J. Bruce Fields
2019-07-30 23:08 ` J. Bruce Fields
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