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    SubjectRe: [Patch 7/9] fs/exec.c: fix wrong return value of prepare_binprm()
    On Mon, May 12, 2008 at 05:01:22AM +0100, Al Viro wrote:
    >On Mon, May 12, 2008 at 11:56:43AM +0800, WANG Cong wrote:
    >> On Sat, May 10, 2008 at 08:31:05PM +0100, Al Viro wrote:
    >> >On Thu, May 08, 2008 at 09:52:32PM +0800, WANG Cong wrote:
    >> >> All prepare_binprm()'s callers assume that prepare_binprm() fails
    >> >> when it returns negative. However, prepare_binprm() most probably returns
    >> >> the return value of kernel_read(), which may return positive on failure!
    >> >>
    >> >> Thus this should be fixed.
    >> >
    >> >Since when does read return positive on failure?
    >>
    >> When an EIO occurs, I think. For example,
    >
    >No. On EIO it returns -EIO, TYVM...
    >

    Hmm, it should. Thanks for your correction.


    >> retval = kernel_read(interpreter, interp_elf_ex->e_phoff,
    >> (char *)elf_phdata,size);
    >> error = -EIO;
    >> if (retval != size) {
    >> if (retval < 0)
    >> error = retval;
    >> goto out_close;
    >> }
    >
    >Which is what we do on short read here. FWIW, -EINVAL might be saner
    >choice - it's "binary is corrupted", not "read had failed".

    IMO, -EIO is fine, because -EINVAL means "Invalid argument", but
    there's nothing wrong with arguments here, just some bad things occurred
    on reading the binary.

    And even if it is really "binary is corrupted", then -ENOEXEC is
    better than -EINVAL, isn't it?

    Anyway, kernel_read() may return postive when not success.

    Thanks.

    --
    Hi, I'm a .signature virus, please copy/paste me to help me spread
    all over the world.


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