From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
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@xxxxxxxxxx>
Fixes: 24ac23ab88df ("NFSv4: Convert open() into an asynchronous RPC call")
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
---
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 9d40319e063d..405f17e6e0b4 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -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;
--
2.47.0
