From 2cbdad4ecc4c6be335167b08b25ab0e9a480a3b6 Mon Sep 17 00:00:00 2001 From: Breno Leitao Date: Tue, 16 Jul 2024 15:10:24 +0800 Subject: [PATCH] netpoll: Fix race condition in netpoll_owner_active mainline inclusion from mainline-v6.10-rc1 commit c2e6a872bde9912f1a7579639c5ca3adf1003916 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IACR1O CVE: CVE-2024-41005 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c2e6a872bde9912f1a7579639c5ca3adf1003916 -------------------------------- KCSAN detected a race condition in netpoll: BUG: KCSAN: data-race in net_rx_action / netpoll_send_skb write (marked) to 0xffff8881164168b0 of 4 bytes by interrupt on cpu 10: net_rx_action (./include/linux/netpoll.h:90 net/core/dev.c:6712 net/core/dev.c:6822) read to 0xffff8881164168b0 of 4 bytes by task 1 on cpu 2: netpoll_send_skb (net/core/netpoll.c:319 net/core/netpoll.c:345 net/core/netpoll.c:393) netpoll_send_udp (net/core/netpoll.c:?) value changed: 0x0000000a -> 0xffffffff This happens because netpoll_owner_active() needs to check if the current CPU is the owner of the lock, touching napi->poll_owner non atomically. The ->poll_owner field contains the current CPU holding the lock. Use an atomic read to check if the poll owner is the current CPU. Signed-off-by: Breno Leitao Link: https://lore.kernel.org/r/20240429100437.3487432-1-leitao@debian.org Signed-off-by: Jakub Kicinski Conflicts: net/core/netpoll.c [The conflict occurs because the commit 5251ef829932("net: make sure napi_list is safe for RCU traversal") is not merged] Signed-off-by: Zhengchao Shao --- net/core/netpoll.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/core/netpoll.c b/net/core/netpoll.c index b23c32ed6773..f1a830550e0c 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -315,7 +315,7 @@ static int netpoll_owner_active(struct net_device *dev) struct napi_struct *napi; list_for_each_entry(napi, &dev->napi_list, dev_list) { - if (napi->poll_owner == smp_processor_id()) + if (READ_ONCE(napi->poll_owner) == smp_processor_id()) return 1; } return 0; -- Gitee