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    Subject[PATCH 4.4 030/312] bpf, mips: fix off-by-one in ctx offset allocation
    Date
    From: Daniel Borkmann <daniel@iogearbox.net>

    commit b4e76f7e6d3200462c6354a6ad4ae167459e61f8 upstream.

    Dan Carpenter reported [1] a static checker warning that ctx->offsets[]
    may be accessed off by one from build_body(), since it's allocated with
    fp->len * sizeof(*ctx.offsets) as length. The cBPF arm and ppc code
    doesn't have this issue as claimed, so only mips seems to be affected and
    should like most other JITs allocate with fp->len + 1. A few number of
    JITs (x86, sparc, arm64) handle this differently, where they only require
    fp->len array elements.

    [1] http://www.spinics.net/lists/mips/msg64193.html

    Fixes: c6610de353da ("MIPS: net: Add BPF JIT")
    Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
    Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
    Cc: Alexei Starovoitov <ast@kernel.org>
    Cc: ast@kernel.org
    Cc: linux-mips@linux-mips.org
    Cc: linux-mips@linux-mips.org
    Patchwork: https://patchwork.linux-mips.org/patch/13814/
    Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/mips/net/bpf_jit.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/arch/mips/net/bpf_jit.c
    +++ b/arch/mips/net/bpf_jit.c
    @@ -1207,7 +1207,7 @@ void bpf_jit_compile(struct bpf_prog *fp

    memset(&ctx, 0, sizeof(ctx));

    - ctx.offsets = kcalloc(fp->len, sizeof(*ctx.offsets), GFP_KERNEL);
    + ctx.offsets = kcalloc(fp->len + 1, sizeof(*ctx.offsets), GFP_KERNEL);
    if (ctx.offsets == NULL)
    return;


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