5.4-stable review patch. If anyone has any objections, please let me know.
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From: Trond Myklebust trond.myklebust@hammerspace.com
[ Upstream commit 2fdb05dc0931250574f0cb0ebeb5ed8e20f4a889 ]
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: 24ac23ab88df ("NFSv4: Convert open() into an asynchronous RPC call") Reviewed-by: Yang Erkun yangerkun@huawei.com Signed-off-by: Trond Myklebust trond.myklebust@hammerspace.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/nfs/nfs4proc.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index 31503bade3358..632cea3fb91da 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -2477,12 +2477,14 @@ 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;