From 5ee0ceddc7785c6dcf4a8107fef01f0414a354f4 Mon Sep 17 00:00:00 2001 From: Mahanta Jambigi Date: Tue, 18 Aug 2026 09:39:43 +0200 Subject: [PATCH] net/smc: free pending qentry in smc_llc_flow_stop() before memset smc_llc_flow_stop() resets a flow struct with a blind memset: spin_lock_bh(&lgr->llc_flow_lock); memset(flow, 0, sizeof(*flow)); flow->type = SMC_LLC_FLOW_NONE; spin_unlock_bh(&lgr->llc_flow_lock); If flow->qentry is non-NULL at this point the pointer is overwritten without the allocation being freed, leaking one kmalloc object. A late-arriving duplicate CONFIRM_LINK or ADD_LINK_CONT message can set flow->qentry after the legitimate message has been consumed by the waiter via smc_llc_flow_qentry_clr() (which NULLs the pointer but leaves flow->type non-zero) but before the flow completes and smc_llc_flow_stop() runs. In that window the duplicate is stashed into flow->qentry, and then lost when smc_llc_flow_stop() zeros the struct. Call smc_llc_flow_qentry_del() inside the lock before the memset. smc_llc_flow_qentry_del() already checks flow->qentry before freeing, so the normal case where no entry is pending is a no-op. Fixes: 555da9af827d ("net/smc: add event-based llc_flow framework") Reviewed-by: Hidayath Khan Signed-off-by: Mahanta Jambigi Link: https://patch.msgid.link/20260818073943.1108383-1-mjambigi@linux.ibm.com Signed-off-by: Jakub Kicinski --- net/smc/smc_llc.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/smc/smc_llc.c b/net/smc/smc_llc.c index c7f0222aff8d..cef2c1df3ab9 100644 --- a/net/smc/smc_llc.c +++ b/net/smc/smc_llc.c @@ -320,6 +320,7 @@ int smc_llc_flow_initiate(struct smc_link_group *lgr, void smc_llc_flow_stop(struct smc_link_group *lgr, struct smc_llc_flow *flow) { spin_lock_bh(&lgr->llc_flow_lock); + smc_llc_flow_qentry_del(flow); memset(flow, 0, sizeof(*flow)); flow->type = SMC_LLC_FLOW_NONE; spin_unlock_bh(&lgr->llc_flow_lock);