1. 17 May, 2023 32 commits
  2. 16 May, 2023 7 commits
  3. 15 May, 2023 1 commit
    • Yafang Shao's avatar
      bpf: Fix memleak due to fentry attach failure · 108598c3
      Yafang Shao authored
      If it fails to attach fentry, the allocated bpf trampoline image will be
      left in the system. That can be verified by checking /proc/kallsyms.
      
      This meamleak can be verified by a simple bpf program as follows:
      
        SEC("fentry/trap_init")
        int fentry_run()
        {
            return 0;
        }
      
      It will fail to attach trap_init because this function is freed after
      kernel init, and then we can find the trampoline image is left in the
      system by checking /proc/kallsyms.
      
        $ tail /proc/kallsyms
        ffffffffc0613000 t bpf_trampoline_6442453466_1  [bpf]
        ffffffffc06c3000 t bpf_trampoline_6442453466_1  [bpf]
      
        $ bpftool btf dump file /sys/kernel/btf/vmlinux | grep "FUNC 'trap_init'"
        [2522] FUNC 'trap_init' type_id=119 linkage=static
      
        $ echo $((6442453466 & 0x7fffffff))
        2522
      
      Note that there are two left bpf trampoline images, that is because the
      libbpf will fallback to raw tracepoint if -EINVAL is returned.
      
      Fixes: e21aa341 ("bpf: Fix fexit trampoline.")
      Signed-off-by: default avatarYafang Shao <laoar.shao@gmail.com>
      Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      Acked-by: default avatarSong Liu <song@kernel.org>
      Cc: Jiri Olsa <olsajiri@gmail.com>
      Link: https://lore.kernel.org/bpf/20230515130849.57502-2-laoar.shao@gmail.com
      108598c3