From: Jiayuan Chen Add a selftest to reproduce the infinite recursion in bond_header_parse() when bonds are stacked (bond1 -> bond0 -> gre). When a packet is received via AF_PACKET SOCK_DGRAM on the topmost bond, dev_parse_header() calls bond_header_parse() which used skb->dev (always the topmost bond) to get the bonding struct. This caused it to recurse back into itself indefinitely, leading to stack overflow. Before commit b7405dcf7385 ("bonding: prevent potential infinite loop in bond_header_parse()"), the test triggers: ./bond_stacked_header_parse.sh [ 71.999481] BUG: MAX_LOCK_DEPTH too low! [ 72.000170] turning off the locking correctness validator. [ 72.001029] Please attach the output of /proc/lock_stat to the bug report [ 72.002079] depth: 48 max: 48! ... After the fix, everything works fine: ./bond_stacked_header_parse.sh TEST: Stacked bond header_parse does not recurse [ OK ] Cc: Jiayuan Chen Signed-off-by: Jiayuan Chen --- Changes in v2: - Use tcpdump + scapy instead of custom Python script - Remove unnecessary modprobe and skip checks - Add CONFIG_NET_IPGRE to config dependencies v1: https://lore.kernel.org/netdev/20260316165946.46e9f8f7@kernel.org/T/#t https://lore.kernel.org/netdev/CANn89iK2EURqsjtd=OVP4awYTJHGcR-UU-V9WovpWR1Z3f03oQ@mail.gmail.com/ --- .../selftests/drivers/net/bonding/Makefile | 1 + .../net/bonding/bond_stacked_header_parse.sh | 69 +++++++++++++++++++ .../selftests/drivers/net/bonding/config | 1 + 3 files changed, 71 insertions(+) create mode 100755 tools/testing/selftests/drivers/net/bonding/bond_stacked_header_parse.sh diff --git a/tools/testing/selftests/drivers/net/bonding/Makefile b/tools/testing/selftests/drivers/net/bonding/Makefile index 6c5c60adb5e8..9af5f84edd37 100644 --- a/tools/testing/selftests/drivers/net/bonding/Makefile +++ b/tools/testing/selftests/drivers/net/bonding/Makefile @@ -11,6 +11,7 @@ TEST_PROGS := \ bond_macvlan_ipvlan.sh \ bond_options.sh \ bond_passive_lacp.sh \ + bond_stacked_header_parse.sh \ dev_addr_lists.sh \ mode-1-recovery-updelay.sh \ mode-2-recovery-updelay.sh \ diff --git a/tools/testing/selftests/drivers/net/bonding/bond_stacked_header_parse.sh b/tools/testing/selftests/drivers/net/bonding/bond_stacked_header_parse.sh new file mode 100755 index 000000000000..4d0ec6e89e75 --- /dev/null +++ b/tools/testing/selftests/drivers/net/bonding/bond_stacked_header_parse.sh @@ -0,0 +1,69 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# +# Test that bond_header_parse() does not infinitely recurse with stacked bonds. +# +# When a non-Ethernet device (e.g. GRE) is enslaved to a bond that is itself +# enslaved to another bond (bond1 -> bond0 -> gre), receiving a packet via +# AF_PACKET SOCK_DGRAM triggers dev_parse_header() -> bond_header_parse(). +# Since parse() used skb->dev (always the topmost bond) instead of a passed-in +# dev pointer, it would recurse back into itself indefinitely. + +ALL_TESTS=" + bond_test_stacked_header_parse +" +REQUIRE_MZ=no +NUM_NETIFS=0 +lib_dir=$(dirname "$0") +source "$lib_dir"/../../../net/forwarding/lib.sh + +bond_test_stacked_header_parse() +{ + local devdummy="test-dummy0" + local devgre="test-gre0" + local devbond0="test-bond0" + local devbond1="test-bond1" + + RET=0 + + # Setup: dummy -> gre -> bond0 -> bond1 + ip link add name "$devdummy" type dummy + ip addr add 10.0.0.1/24 dev "$devdummy" + ip link set "$devdummy" up + + ip link add name "$devgre" type gre local 10.0.0.1 + + ip link add name "$devbond0" type bond mode active-backup + ip link add name "$devbond1" type bond mode active-backup + + ip link set "$devgre" master "$devbond0" + ip link set "$devbond0" master "$devbond1" + + ip link set "$devgre" up + ip link set "$devbond0" up + ip link set "$devbond1" up + + # tcpdump on a non-Ethernet bond uses AF_PACKET SOCK_DGRAM (cooked + # capture), which triggers dev_parse_header() -> bond_header_parse() + # on receive. With the bug, this recurses infinitely. + timeout 5 tcpdump -c 1 -i "$devbond1" >/dev/null 2>&1 & + local tcpdump_pid=$! + sleep 1 + + # Send a GRE packet to 10.0.0.1 so it arrives via gre -> bond0 -> bond1 + python3 -c "from scapy.all import *; send(IP(src='10.0.0.2', dst='10.0.0.1')/GRE()/IP()/UDP(), verbose=0)" + check_err $? "failed to send GRE packet (scapy installed?)" + + wait "$tcpdump_pid" 2>/dev/null + + ip link del "$devbond1" 2>/dev/null + ip link del "$devbond0" 2>/dev/null + ip link del "$devgre" 2>/dev/null + ip link del "$devdummy" 2>/dev/null + + log_test "Stacked bond header_parse does not recurse" +} + +tests_run + +exit "$EXIT_STATUS" diff --git a/tools/testing/selftests/drivers/net/bonding/config b/tools/testing/selftests/drivers/net/bonding/config index 991494376223..14f21f0e4d2f 100644 --- a/tools/testing/selftests/drivers/net/bonding/config +++ b/tools/testing/selftests/drivers/net/bonding/config @@ -13,6 +13,7 @@ CONFIG_NET_CLS_MATCHALL=m CONFIG_NETCONSOLE=m CONFIG_NETCONSOLE_DYNAMIC=y CONFIG_NETCONSOLE_EXTENDED_LOG=y +CONFIG_NET_IPGRE=y CONFIG_NETDEVSIM=m CONFIG_NET_SCH_INGRESS=y CONFIG_NLMON=y -- 2.43.0