From a5f7a5bb3b7f28ba7e4fa246775b29a0e5537255 Mon Sep 17 00:00:00 2001 From: Jinke Han Date: Tue, 8 Sep 2026 15:37:42 +0800 Subject: x86/kprobes: Fix crash when probing CS CALL instructions When using eBPF to probe CS CALL instructions within a function, a crash can be triggered. The eBPF tool probes offset 257 of the __hrtimer_run_queues() function: <__hrtimer_run_queues+249>: nopl 0x0(%rax,%rax,1) <__hrtimer_run_queues+254>: mov %r14,%rdi <__hrtimer_run_queues+257>: cs call <__x86_indirect_thunk_r12> <__hrtimer_run_queues+263>: mov %eax,%r12d <__hrtimer_run_queues+266>: xchg %ax,%ax <__hrtimer_run_queues+268>: mov %r13,%rdi Which triggers this crash: BUG: unable to handle page fault for address: 00000000000f41c9 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: 0002 [#1] SMP NOPTI CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P RIP: 0010:__hrtimer_run_queues+0x106/0x230 Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is at the 6th byte of the above CS CALL instruction. Since the CS CALL instruction occupies 6 bytes, the exception occurred in the middle of that call instruction. The root cause is that when using eBPF tools to probe in the middle of a function, a kprobe with INT3 is used as the underlying implementation. During single-step emulation of the original CALL instruction, int3_emulate_call() assumes that the probed CALL instruction is 5 bytes long. However, the actual CS-prefixed CALL instruction occupies 6 bytes, so it constructs an incorrect exception return address. When the CPU returns from the kprobe handler, the next instruction to be executed is at the address of the last byte of that CS CALL instruction. Coincidentally, starting from that address, the CPU fetches and decodes a completely different instruction, which ultimately triggers a kernel crash. Fix the issue by using the actual instruction length obtained from the instruction decoder when constructing the exception return address, rather than relying on the hardcoded CALL_INSN_SIZE macro. [ mingo: Refined the changelog ] Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step") Suggested-by: Masami Hiramatsu (Google) Signed-off-by: Jinke Han Signed-off-by: Ingo Molnar Reviewed-by: Masami Hiramatsu (Google) Acked-by: Yafang Shao Acked-by: Borislav Petkov Cc: Peter Zijlstra Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000 --- net/bridge/Kconfig | 85 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 85 insertions(+) create mode 100644 net/bridge/Kconfig (limited to 'net/bridge/Kconfig') diff --git a/net/bridge/Kconfig b/net/bridge/Kconfig new file mode 100644 index 000000000..318715c8f --- /dev/null +++ b/net/bridge/Kconfig @@ -0,0 +1,85 @@ +# SPDX-License-Identifier: GPL-2.0-only +# +# 802.1d Ethernet Bridging +# + +config BRIDGE + tristate "802.1d Ethernet Bridging" + select LLC + select STP + help + If you say Y here, then your Linux box will be able to act as an + Ethernet bridge, which means that the different Ethernet segments it + is connected to will appear as one Ethernet to the participants. + Several such bridges can work together to create even larger + networks of Ethernets using the IEEE 802.1 spanning tree algorithm. + As this is a standard, Linux bridges will cooperate properly with + other third party bridge products. + + In order to use the Ethernet bridge, you'll need the bridge + configuration tools; see + for location. Please read the Bridge mini-HOWTO for more + information. + + If you enable iptables support along with the bridge support then you + turn your bridge into a bridging IP firewall. + iptables will then see the IP packets being bridged, so you need to + take this into account when setting up your firewall rules. + Enabling arptables support when bridging will let arptables see + bridged ARP traffic in the arptables FORWARD chain. + + To compile this code as a module, choose M here: the module + will be called bridge. + + If unsure, say N. + +config BRIDGE_IGMP_SNOOPING + bool "IGMP/MLD snooping" + depends on BRIDGE + depends on INET + default y + help + If you say Y here, then the Ethernet bridge will be able selectively + forward multicast traffic based on IGMP/MLD traffic received from + each port. + + Say N to exclude this support and reduce the binary size. + + If unsure, say Y. + +config BRIDGE_VLAN_FILTERING + bool "VLAN filtering" + depends on BRIDGE + depends on VLAN_8021Q + default n + help + If you say Y here, then the Ethernet bridge will be able selectively + receive and forward traffic based on VLAN information in the packet + any VLAN information configured on the bridge port or bridge device. + + Say N to exclude this support and reduce the binary size. + + If unsure, say Y. + +config BRIDGE_MRP + bool "MRP protocol" + depends on BRIDGE + default n + help + If you say Y here, then the Ethernet bridge will be able to run MRP + protocol to detect loops + + Say N to exclude this support and reduce the binary size. + + If unsure, say N. + +config BRIDGE_CFM + bool "CFM protocol" + depends on BRIDGE + help + If you say Y here, then the Ethernet bridge will be able to run CFM + protocol according to 802.1Q section 12.14 + + Say N to exclude this support and reduce the binary size. + + If unsure, say N. -- cgit v1.3.1