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 --- drivers/net/team/Kconfig | 77 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 77 insertions(+) create mode 100644 drivers/net/team/Kconfig (limited to 'drivers/net/team/Kconfig') diff --git a/drivers/net/team/Kconfig b/drivers/net/team/Kconfig new file mode 100644 index 000000000..4d449845d --- /dev/null +++ b/drivers/net/team/Kconfig @@ -0,0 +1,77 @@ +# SPDX-License-Identifier: GPL-2.0-only +menuconfig NET_TEAM + tristate "Ethernet team driver support" + help + This allows one to create virtual interfaces that teams together + multiple ethernet devices. + + Team devices can be added using the "ip" command from the + iproute2 package: + + "ip link add link [ address MAC ] [ NAME ] type team" + + To compile this driver as a module, choose M here: the module + will be called team. + +if NET_TEAM + +config NET_TEAM_MODE_BROADCAST + tristate "Broadcast mode support" + depends on NET_TEAM + help + Basic mode where packets are transmitted always by all suitable ports. + + All added ports are setup to have team's device address. + + To compile this team mode as a module, choose M here: the module + will be called team_mode_broadcast. + +config NET_TEAM_MODE_ROUNDROBIN + tristate "Round-robin mode support" + depends on NET_TEAM + help + Basic mode where port used for transmitting packets is selected in + round-robin fashion using packet counter. + + All added ports are setup to have team's device address. + + To compile this team mode as a module, choose M here: the module + will be called team_mode_roundrobin. + +config NET_TEAM_MODE_RANDOM + tristate "Random mode support" + depends on NET_TEAM + help + Basic mode where port used for transmitting packets is selected + randomly. + + All added ports are setup to have team's device address. + + To compile this team mode as a module, choose M here: the module + will be called team_mode_random. + +config NET_TEAM_MODE_ACTIVEBACKUP + tristate "Active-backup mode support" + depends on NET_TEAM + help + Only one port is active at a time and the rest of ports are used + for backup. + + Mac addresses of ports are not modified. Userspace is responsible + to do so. + + To compile this team mode as a module, choose M here: the module + will be called team_mode_activebackup. + +config NET_TEAM_MODE_LOADBALANCE + tristate "Load-balance mode support" + depends on NET_TEAM + help + This mode provides load balancing functionality. Tx port selection + is done using BPF function set up from userspace (bpf_hash_func + option) + + To compile this team mode as a module, choose M here: the module + will be called team_mode_loadbalance. + +endif # NET_TEAM -- cgit v1.3.1