From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: ppandit@redhat.com
Cc: keescook@chromium.org, viro@zeniv.linux.org.uk,
linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
josh@joshtriplett.org, serge.hallyn@canonical.com,
linux-fsdevel@vger.kernel.org, me@halfdog.net
Subject: Re: [PATCH] exec: do not leave bprm->interp on stack
Date: Sat, 24 Nov 2012 08:12:36 +0900 [thread overview]
Message-ID: <201211240812.HAE95846.FSQOFFtOJHLOMV@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <alpine.LFD.2.02.1211240004060.15883@wniryva.cad.erqung.pbz>
P J P wrote:
>
> Hello Kees, all,
>
> Please have a look at a *NEW* patch at the end of this mail. It seems to fix
> both the issues, stack disclosure + undue recursions.
>
> It uses modprobe "--first-time" option which returns an error code when trying
> to load a module which is already present or unload one which is not present.
It might fix both "stack disclosure" + "undue recursions" issues, but it
introduces a regression "only one of concurrent requesters succeeds" which
ruins the value of automatic module loading feature.
> @@ -1423,7 +1423,14 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
> break; /* -ENOEXEC */
> if (try)
> break; /* -ENOEXEC */
> - request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
What happens if more than one processes are requesting execve() of a program
which needs to call request_module("binfmt-%04x") to succeed, and more than two
of them concurrently reached at this line? Only one process will succeed. This
means that execve() of a program which needs to call request_module() will fail
if concurrently reached here.
> + if (request_module("binfmt-%04x",
> + *(unsigned short *)(&bprm->buf[2])))
> + {
> + printk(KERN_WARNING
> + "request_module: failed to load: binfmt-%04x",
> + *(unsigned short *)(&bprm->buf[2]));
> + break;
> + }
> }
> #else
> break;
next prev parent reply other threads:[~2012-11-23 23:13 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-24 23:20 [PATCH] exec: do not leave bprm->interp on stack Kees Cook
2012-10-25 4:16 ` Al Viro
2012-10-25 6:21 ` Kees Cook
2012-10-25 11:46 ` P J P
2012-10-25 12:03 ` Tetsuo Handa
2012-10-25 12:57 ` P J P
2012-10-25 12:09 ` Al Viro
2012-10-25 12:38 ` Al Viro
2012-10-26 17:38 ` P J P
2012-10-26 18:36 ` Al Viro
2012-10-27 10:47 ` P J P
2012-10-27 17:05 ` Kees Cook
2012-10-27 20:16 ` P J P
2012-10-28 3:32 ` Kees Cook
2012-11-06 8:10 ` P J P
2012-11-12 22:10 ` Kees Cook
2012-11-13 6:50 ` halfdog
2012-11-16 12:50 ` P J P
2012-11-16 18:00 ` Kees Cook
2012-11-18 19:04 ` P J P
2012-11-18 19:34 ` Kees Cook
2012-11-19 6:57 ` P J P
2012-11-19 20:41 ` Kees Cook
2012-11-20 7:04 ` P J P
2012-11-22 20:06 ` P J P
2012-11-23 18:43 ` P J P
2012-11-23 23:12 ` Tetsuo Handa [this message]
[not found] ` <alpine.LFD.2.02.1211221934220.19768@wniryva.cad.erqung.pbz>
[not found] ` <CAGXu5jL8zCt5ghW4ODPL9+SyC9+mbuw=4JMUngepY5fC8pSikQ@mail.gmail.com>
2012-11-26 7:09 ` P J P
[not found] ` <CA+55aFx3LFH5Xj1OkNoy7vN5w8y5tH39MUDujKqF3BdnmYibLQ@mail.gmail.com>
2012-11-20 7:08 ` P J P
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