DEBIAN-CVE-2026-72466

In the Linux kernel, the following vulnerability has been resolved:  xprtrdma: Fix bcall rep leak and unbounded peek  rpcrdmaisbcall() decodes a reply's first words to decide whether the frame is a backchannel call. Two issues in that decode path let a short or malformed reply leak the receive buffer and drain the Receive queue.  First, the speculative peek      p = xdrinlinedecode(xdr, 0);     / five p++ reads follow /  asks xdrinlinedecode() for zero bytes, which returns xdr->p without consulting xdr->end. The five subsequent _be32 reads can then walk up to 20 bytes past the wire payload into stale regbuf contents and misclassify the reply as a backchannel call.  Second, after the post-peek      p = xdrinlinedecode(xdr, 3  sizeof(p));     if (unlikely(!p))             return true;  the short-header arm returns true without calling rpcrdmabcreceivecall(). The contract with the caller is that a true return transfers ownership of rep to the backchannel path:      rpcrdmareplyhandler()       if (rpcrdmaisbcall(rxprt, rep))               return;        /* bare return, skips outpost */       ...     outpost:       rpcrdmapostrecvs(rxprt, credits + ...);  Because rpcrdmabcreceivecall() never ran, no one took rep, but rpcrdmareplyhandler still bare-returns past rpcrdmarepput() and rpcrdmapostrecvs(). The rep, with its persistently DMA-mapped receive buffer, is orphaned on rballreps and freed only at transport teardown. This completion reposts nothing, so its slot is reclaimed only when a later forward-channel reply reaches outpost and rpcrdmapostrecvs() allocates a fresh rep to backfill; absent that traffic the Receive queue drains and the peer's Sends draw RNR NAKs.  Fix by consulting xdr->end after the zero-length peek so the five _be32 reads cannot run unless 20 bytes of wire payload remain. A byte-precise comparison against xdr->end is required because a non-4-aligned receive rounds the stream's word count up past the true payload. Also return false from the short-header arm so the reply falls through the normal outnorqst cleanup chain (rpcrdmarepput() plus rpcrdmapostrecvs()).