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    SubjectRe: [PATCH 16/36] tty/vt: consolemap: check put_user() in con_get_unimap()
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    On 07. 06. 22, 16:19, Ilpo Järvinen wrote:
    > On Tue, 7 Jun 2022, Jiri Slaby wrote:
    >
    >> Only the return value of copy_to_user() is checked in con_get_unimap().
    >> Do the same for put_user() of the count too.
    >>
    >> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
    >> ---
    >> drivers/tty/vt/consolemap.c | 3 ++-
    >> 1 file changed, 2 insertions(+), 1 deletion(-)
    >>
    >> diff --git a/drivers/tty/vt/consolemap.c b/drivers/tty/vt/consolemap.c
    >> index 831450f2bfd1..92b5dddb00d9 100644
    >> --- a/drivers/tty/vt/consolemap.c
    >> +++ b/drivers/tty/vt/consolemap.c
    >> @@ -813,7 +813,8 @@ int con_get_unimap(struct vc_data *vc, ushort ct, ushort __user *uct,
    >> console_unlock();
    >> if (copy_to_user(list, unilist, min(ect, ct) * sizeof(*unilist)))
    >> ret = -EFAULT;
    >> - put_user(ect, uct);
    >> + if (put_user(ect, uct))
    >> + ret = -EFAULT;
    >> kvfree(unilist);
    >> return ret ? ret : (ect <= ct) ? 0 : -ENOMEM;
    >> }
    >>
    >
    > Doesn't this fix something?

    If you mean a Fixes tag, this is pre-git.

    If you mean a bug, well, likely yes, users now get informed. But I don't
    think anyone cares ;). But who knows, maybe we will start seeing
    userspace failures now (as they might not provide writable count field
    -- unlikely). That's one of the reasons why I did this as a separate
    commit. Let's see if are going to revert this or not...

    thanks,
    --
    js
    suse labs

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