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NFSv4.0: Fix a use-after-free problem in the asynchronous open()

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Yang Erkun reports that when two threads are opening files at the same
time, and are forced to abort before a reply is seen, then the call to
nfs_release_seqid() in nfs4_opendata_free() can result in a
use-after-free of the pointer to the defunct rpc task of the other
thread.
The fix is to ensure that if the RPC call is aborted before the call to
nfs_wait_on_sequence() is complete, then we must call nfs_release_seqid()
in nfs4_open_release() before the rpc_task is freed.

Reported-by: Yang Erkun <yangerkun@huawei.com>
Fixes: 24ac23ab88 ("NFSv4: Convert open() into an asynchronous RPC call")
Reviewed-by: Yang Erkun <yangerkun@huawei.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Trond Myklebust 2024-11-08 12:13:31 -05:00
parent c968fd23c6
commit 2fdb05dc09
1 changed files with 5 additions and 3 deletions
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8
fs/nfs/nfs4proc.c
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@ -2603,12 +2603,14 @@ static void nfs4_open_release(void *calldata)
struct nfs4_opendata *data = calldata;
struct nfs4_state *state = NULL;
/* In case of error, no cleanup! */
if (data->rpc_status != 0 || !data->rpc_done) {
nfs_release_seqid(data->o_arg.seqid);
goto out_free;
}
/* If this request hasn't been cancelled, do nothing */
if (!data->cancelled)
goto out_free;
/* In case of error, no cleanup! */
if (data->rpc_status != 0 || !data->rpc_done)
goto out_free;
/* In case we need an open_confirm, no cleanup! */
if (data->o_res.rflags & NFS4_OPEN_RESULT_CONFIRM)
goto out_free;