linux-kernel - Re: [PATCH] Reset current->pdeath

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Message-ID: <CAKgNAkgJYjACsoOKhFZirPW_SrZ9Rwn7MMch_1GbrrNWFxhu+w@mail.gmail.com>
Date:	Mon, 23 Apr 2012 21:34:27 +1200
From:	"Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>
To:	Marcel Holtmann <marcel@...tmann.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, mtk-manpages@....net
Subject: Re: [PATCH] Reset current->pdeath_signal on SUID binary execution

Marcel,

On Sat, Aug 18, 2007 at 7:47 AM, Marcel Holtmann <marcel@...tmann.org> wrote:
> Hi Linus,
>
> the attached patch fixes a flaw in the "parent process death signal"
> when executing SUID binaries. An unprivileged user may send arbitrary
> signal to a child process even if it is running with higher privileges.
>
> The idea to fix this issue is to reset pdeath_signal not only on fork,
> but also on the execution of a SUID binary.
>
> Michael, if we fix it this way, then the prctl() manual page should
> reflect that behavior.

For man-pages-3.40, I applied the patch below.

Cheers,

Michael

--- a/man2/prctl.2
+++ b/man2/prctl.2
@@ -220,7 +220,9 @@ in the range 1..maxsig, or 0 to clear).
 This is the signal that the calling process will get when its
 parent dies.
 This value is cleared for the child of a
-.BR fork (2).
+.BR fork (2)
+and (since Linux 2.5.36 / 2.6.23)
+when execing a set-user_ID or set-group-ID binary.
 .TP
 .BR PR_GET_PDEATHSIG " (since Linux 2.3.15)"
 Return the current value of the parent process death signal,


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Author of "The Linux Programming Interface"; http://man7.org/tlpi/
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