[SRU][N][PATCH 1/1] NFSv4.0: Fix a use-after-free problem in the asynchronous open()

[Bethany Jamison]

From: Trond Myklebust <trond.myklebust at 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 at huawei.com>
Fixes: 24ac23ab88df ("NFSv4: Convert open() into an asynchronous RPC call")
Reviewed-by: Yang Erkun <yangerkun at huawei.com>
Signed-off-by: Trond Myklebust <trond.myklebust at hammerspace.com>
Signed-off-by: Sasha Levin <sashal at kernel.org>
(cherry picked from commit e2277a1d9d5cd0d625a4fd7c04fce2b53e66df77 linux-6.11.y)
CVE-2024-53173
Signed-off-by: Bethany Jamison <bethany.jamison at canonical.com>
---
 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 2213b00dd2395..207b3fd688a08 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2552,12 +2552,14 @@ 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;
-- 
2.43.0