diff mbox series

[net,3/4] netem: update sch->q.qlen before qdisc_tree_reduce_backlog()

Message ID 20250124060740.356527-4-xiyou.wangcong@gmail.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series net_sched: two security bug fixes and test cases | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers fail 1 blamed authors not CCed: kuba@kernel.org; 5 maintainers not CCed: stephen@networkplumber.org pabeni@redhat.com edumazet@google.com horms@kernel.org kuba@kernel.org
netdev/build_clang success Errors and warnings before: 1 this patch: 1
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch warning WARNING: line length of 83 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest fail net-next-2025-01-24--12-00 (tests: 877)

Commit Message

Cong Wang Jan. 24, 2025, 6:07 a.m. UTC 
From: Cong Wang <cong.wang@bytedance.com>

qdisc_tree_reduce_backlog() notifies parent qdisc only if child
qdisc becomes empty, therefore we need to reduce the backlog of the
child qdisc before calling it. Otherwise it would become a nop and
result in UAF in DRR case (which is integrated in the following patch).

Fixes: f8d4bc455047 ("net/sched: netem: account for backlog updates from child qdisc")
Cc: Martin Ottens <martin.ottens@fau.de>
Reported-by: Mingi Cho <mincho@theori.io>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
---
 net/sched/sch_netem.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 71ec9986ed37..fdd79d3ccd8c 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -749,9 +749,9 @@  static struct sk_buff *netem_dequeue(struct Qdisc *sch)
 				if (err != NET_XMIT_SUCCESS) {
 					if (net_xmit_drop_count(err))
 						qdisc_qstats_drop(sch);
-					qdisc_tree_reduce_backlog(sch, 1, pkt_len);
 					sch->qstats.backlog -= pkt_len;
 					sch->q.qlen--;
+					qdisc_tree_reduce_backlog(sch, 1, pkt_len);
 				}
 				goto tfifo_dequeue;
 			}