From: NeilBrown Date: Mon, 8 May 2023 23:41:49 +0000 (+1000) Subject: SUNRPC: double free xprt_ctxt while still in use X-Git-Tag: v6.1.37~997 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=fd86534872f445f54dc01e7db001e25eadf063a8;p=platform%2Fkernel%2Flinux-starfive.git SUNRPC: double free xprt_ctxt while still in use [ Upstream commit eb8d3a2c809abd73ab0a060fe971d6b9019aa3c1 ] When an RPC request is deferred, the rq_xprt_ctxt pointer is moved out of the svc_rqst into the svc_deferred_req. When the deferred request is revisited, the pointer is copied into the new svc_rqst - and also remains in the svc_deferred_req. In the (rare?) case that the request is deferred a second time, the old svc_deferred_req is reused - it still has all the correct content. However in that case the rq_xprt_ctxt pointer is NOT cleared so that when xpo_release_xprt is called, the ctxt is freed (UDP) or possible added to a free list (RDMA). When the deferred request is revisited for a second time, it will reference this ctxt which may be invalid, and the free the object a second time which is likely to oops. So change svc_defer() to *always* clear rq_xprt_ctxt, and assert that the value is now stored in the svc_deferred_req. Fixes: 773f91b2cf3f ("SUNRPC: Fix NFSD's request deferral on RDMA transports") Signed-off-by: NeilBrown Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin --- diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c index c2ce125..b4306cf 100644 --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -1228,13 +1228,14 @@ static struct cache_deferred_req *svc_defer(struct cache_req *req) dr->daddr = rqstp->rq_daddr; dr->argslen = rqstp->rq_arg.len >> 2; dr->xprt_ctxt = rqstp->rq_xprt_ctxt; - rqstp->rq_xprt_ctxt = NULL; /* back up head to the start of the buffer and copy */ skip = rqstp->rq_arg.len - rqstp->rq_arg.head[0].iov_len; memcpy(dr->args, rqstp->rq_arg.head[0].iov_base - skip, dr->argslen << 2); } + WARN_ON_ONCE(rqstp->rq_xprt_ctxt != dr->xprt_ctxt); + rqstp->rq_xprt_ctxt = NULL; trace_svc_defer(rqstp); svc_xprt_get(rqstp->rq_xprt); dr->xprt = rqstp->rq_xprt;