From: Marcel Holtmann <marcel@holtmann.org>
Date: Fri, 17 Aug 2007 19:47:58 +0000 (+0200)
Subject: Reset current->pdeath_signal on SUID binary execution
X-Git-Tag: v2.6.23-rc4~134
X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=d2d56c5f51028cb9f3d800882eb6f4cbd3f9099f

Reset current->pdeath_signal on SUID binary execution

This fixes a vulnerability in the "parent process death signal"
implementation discoverd by Wojciech Purczynski of COSEINC PTE Ltd.
and iSEC Security Research.

http://marc.info/?l=bugtraq&m=118711306802632&w=2

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

Backported to Debian's 2.6.18 by dann frazier <dannf@debian.org>

diff -urpN linux-source-2.6.18.orig/fs/exec.c linux-source-2.6.18/fs/exec.c
--- linux-source-2.6.18.orig/fs/exec.c	2007-09-05 14:11:16.000000000 -0600
+++ linux-source-2.6.18/fs/exec.c	2007-09-05 14:17:02.000000000 -0600
@@ -883,9 +883,12 @@ int flush_old_exec(struct linux_binprm *
 	 */
 	current->mm->task_size = TASK_SIZE;
 
-	if (bprm->e_uid != current->euid || bprm->e_gid != current->egid || 
-	    file_permission(bprm->file, MAY_READ) ||
-	    (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
+	if (bprm->e_uid != current->euid || bprm->e_gid != current->egid) {
+		suid_keys(current);
+		current->mm->dumpable = suid_dumpable;
+		current->pdeath_signal = 0;
+	} else if (file_permission(bprm->file, MAY_READ) ||
+			(bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
 		suid_keys(current);
 		current->mm->dumpable = suid_dumpable;
 	}
@@ -977,8 +980,10 @@ void compute_creds(struct linux_binprm *
 {
 	int unsafe;
 
-	if (bprm->e_uid != current->uid)
+	if (bprm->e_uid != current->uid) {
 		suid_keys(current);
+		current->pdeath_signal = 0;
+	}
 	exec_keys(current);
 
 	task_lock(current);