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    Subject[PATCH] Require mmap handler for a.out executables (was Re: 2.6.18-rc2-mm1)
    Hi Andrew,

    Andrew Morton wrote:
    [snipped]
    > - Lots of random patches. Many of them are bugfixes and I shall, as usual,
    > go through them all identifying 2.6.18 material. But I can miss things, so
    > please don't be afraid to point 2.6.18 candidates out to me.
    [snipped]

    The following patch provides better protection against people exploiting stuff
    in /proc and I hope you consider it for upstream inclusion.

    Thanks.

    Eugene

    [PATCH] Require mmap handler for a.out executables

    Files supported by fs/proc/base.c, i.e. /proc/<pid>/*, are not capable
    of meeting the validity checks in ELF load_elf_*() handling because they
    have no mmap handler which is required by ELF. In order to stop a.out
    executables being used as part of an exploit attack against /proc-related
    vulnerabilities, we make a.out executables depend on ->mmap() existing.

    Signed-off-by: Eugene Teo <eteo@redhat.com>
    Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

    ---
    commit 1597cf8405734e4747c808bb7e04115a6670dccf
    tree 49050549aee6406dab0c021c5aa4e9bfc337bd8f
    parent 44eb123126d289bac398cac0232309c228386671
    author Marcel Holtmann <marcel@holtmann.org> Wed, 26 Jul 2006 12:12:14 +0200
    committer Marcel Holtmann <marcel@holtmann.org> Wed, 26 Jul 2006 12:12:14 +0200

    fs/binfmt_aout.c | 6 ++++++
    1 files changed, 6 insertions(+), 0 deletions(-)

    diff --git a/fs/binfmt_aout.c b/fs/binfmt_aout.c
    index f312103..5638acf 100644
    --- a/fs/binfmt_aout.c
    +++ b/fs/binfmt_aout.c
    @@ -278,6 +278,9 @@ static int load_aout_binary(struct linux
    return -ENOEXEC;
    }

    + if (!bprm->file->f_op || !bprm->file->f_op->mmap)
    + return -ENOEXEC;
    +
    fd_offset = N_TXTOFF(ex);

    /* Check initial limits. This avoids letting people circumvent
    @@ -476,6 +479,9 @@ static int load_aout_library(struct file
    goto out;
    }

    + if (!file->f_op || !file->f_op->mmap)
    + goto out;
    +
    if (N_FLAGS(ex))
    goto out;

    --
    eteo redhat.com ph: +65 6490 4142 http://www.kernel.org/~eugeneteo
    gpg fingerprint: 47B9 90F6 AE4A 9C51 37E0 D6E1 EA84 C6A2 58DF 8823
    -
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