From: Anna Schumaker Date: Tue, 30 Jun 2026 18:31:00 +0000 (-0400) Subject: NFS: Pin the 'struct nfs_server' during a FREE_STATEID call X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cf616096a0f3a2b60f7d68b6b39674a6867ded9c;p=thirdparty%2Fkernel%2Flinux.git NFS: Pin the 'struct nfs_server' during a FREE_STATEID call Dan Aloni reports that he was able to hit a use-after-free bug if a FREE_STATEID operation gets delayed for whatever reason. Fix this by bumping the refcount of the 'struct nfs_server' object for the duration of the FREE_STATEID so it doesn't get cleaned up from underneath us while operations are still in flight. Reported-by: Dan Aloni Fixes: 7c1d5fae4a87 ("NFSv4: Convert nfs41_free_stateid to use an asynchronous RPC call") Tested-by: Dan Aloni Signed-off-by: Anna Schumaker --- diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index 1360409d8de9..71b6ab863b39 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -10364,6 +10364,7 @@ static void nfs41_free_stateid_release(void *calldata) struct nfs_free_stateid_data *data = calldata; struct nfs_client *clp = data->server->nfs_client; + nfs_sb_deactive(data->server->super); nfs_put_client(clp); kfree(calldata); } @@ -10405,6 +10406,10 @@ static int nfs41_free_stateid(struct nfs_server *server, if (!refcount_inc_not_zero(&clp->cl_count)) return -EIO; + if (!nfs_sb_active(server->super)) { + nfs_put_client(clp); + return -EIO; + } nfs4_state_protect(clp, NFS_SP4_MACH_CRED_STATEID, &task_setup.rpc_client, &msg);