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kprobes: Skip clearing aggrprobe's post_handler in kprobe-on-ftrace case
In __unregister_kprobe_top(), if the currently unregistered probe has post_handler but other child probes of the aggrprobe do not have post_handler, the post_handler of the aggrprobe is cleared. If this is a ftrace-based probe, there is a problem. In later calls to disarm_kprobe(), we will use kprobe_ftrace_ops because post_handler is NULL. But we're armed with kprobe_ipmodify_ops. This triggers a WARN in __disarm_kprobe_ftrace() and may even cause use-after-free: Failed to disarm kprobe-ftrace at kernel_clone+0x0/0x3c0 (error -2) WARNING: CPU: 5 PID: 137 at kernel/kprobes.c:1135 __disarm_kprobe_ftrace.isra.21+0xcf/0xe0 Modules linked in: testKprobe_007(-) CPU: 5 PID: 137 Comm: rmmod Not tainted 6.1.0-rc4-dirty #18 [...] Call Trace: <TASK> __disable_kprobe+0xcd/0xe0 __unregister_kprobe_top+0x12/0x150 ? mutex_lock+0xe/0x30 unregister_kprobes.part.23+0x31/0xa0 unregister_kprobe+0x32/0x40 __x64_sys_delete_module+0x15e/0x260 ? do_user_addr_fault+0x2cd/0x6b0 do_syscall_64+0x3a/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd [...] For the kprobe-on-ftrace case, we keep the post_handler setting to identify this aggrprobe armed with kprobe_ipmodify_ops. This way we can disarm it correctly. Link: https://lore.kernel.org/all/[email protected]/ Fixes: 0bc11ed ("kprobes: Allow kprobes coexist with livepatch") Reported-by: Zhao Gongyi <[email protected]> Suggested-by: Masami Hiramatsu (Google) <[email protected]> Signed-off-by: Li Huafei <[email protected]> Acked-by: Masami Hiramatsu (Google) <[email protected]> Signed-off-by: Masami Hiramatsu (Google) <[email protected]>
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