• Daniel Borkmann's avatar
    bpf: arsh is not supported in 32 bit alu thus reject it · 7891a87e
    Daniel Borkmann authored
    The following snippet was throwing an 'unknown opcode cc' warning
    in BPF interpreter:
    
      0: (18) r0 = 0x0
      2: (7b) *(u64 *)(r10 -16) = r0
      3: (cc) (u32) r0 s>>= (u32) r0
      4: (95) exit
    
    Although a number of JITs do support BPF_ALU | BPF_ARSH | BPF_{K,X}
    generation, not all of them do and interpreter does neither. We can
    leave existing ones and implement it later in bpf-next for the
    remaining ones, but reject this properly in verifier for the time
    being.
    
    Fixes: 17a52670 ("bpf: verifier (add verifier core)")
    Reported-by: syzbot+93c4904c5c70348a6890@syzkaller.appspotmail.com
    Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
    Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
    7891a87e
verifier.c 138 KB