CVE-2014-3917 DoS with syscall auditing (rhbz 1102571 1102715)

1 files changed, 128 insertions, 0 deletions

diff --git a/auditsc-audit_krule-mask-accesses-need-bounds-checking.patch b/auditsc-audit_krule-mask-accesses-need-bounds-checking.patch
new file mode 100644
index 000000000..1a7763767
--- /dev/null
+++ b/auditsc-audit_krule-mask-accesses-need-bounds-checking.patch
@@ -0,0 +1,128 @@
+Bugzilla: 1102715
+Upstream-status: Submitted for 3.15 and CC'd to stable                                                                                                                                                                                                                                                               
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+From:	Eric Paris <eparis@redhat.com>
+To:	torvalds@linux-foundation.org
+Cc:	linux-audit@redhat.com, linux-kernel@vger.kernel.org,
+	Andy Lutomirski <luto@amacapital.net>, stable@vger.kernel.org,
+	Eric Paris <eparis@redhat.com>
+Subject: [PATCH 1/2] auditsc: audit_krule mask accesses need bounds checking
+Date:	Wed, 28 May 2014 23:09:58 -0400
+Message-Id: <1401332999-15167-1-git-send-email-eparis@redhat.com>
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+
+From: Andy Lutomirski <luto@amacapital.net>
+
+Fixes an easy DoS and possible information disclosure.
+
+This does nothing about the broken state of x32 auditing.
+
+eparis: If the admin has enabled auditd and has specifically loaded audit
+rules.  This bug has been around since before git.  Wow...
+
+Cc: stable@vger.kernel.org
+Signed-off-by: Andy Lutomirski <luto@amacapital.net>
+Signed-off-by: Eric Paris <eparis@redhat.com>
+---
+ kernel/auditsc.c | 27 ++++++++++++++++++---------
+ 1 file changed, 18 insertions(+), 9 deletions(-)
+
+diff --git a/kernel/auditsc.c b/kernel/auditsc.c
+index 254ce20..842f58a 100644
+--- a/kernel/auditsc.c
++++ b/kernel/auditsc.c
+@@ -728,6 +728,22 @@ static enum audit_state audit_filter_task(struct task_struct *tsk, char **key)
+ 	return AUDIT_BUILD_CONTEXT;
+ }
+ 
++static int audit_in_mask(const struct audit_krule *rule, unsigned long val)
++{
++	int word, bit;
++
++	if (val > 0xffffffff)
++		return false;
++
++	word = AUDIT_WORD(val);
++	if (word >= AUDIT_BITMASK_SIZE)
++		return false;
++
++	bit = AUDIT_BIT(val);
++
++	return rule->mask[word] & bit;
++}
++
+ /* At syscall entry and exit time, this filter is called if the
+  * audit_state is not low enough that auditing cannot take place, but is
+  * also not high enough that we already know we have to write an audit
+@@ -745,11 +761,8 @@ static enum audit_state audit_filter_syscall(struct task_struct *tsk,
+ 
+ 	rcu_read_lock();
+ 	if (!list_empty(list)) {
+-		int word = AUDIT_WORD(ctx->major);
+-		int bit  = AUDIT_BIT(ctx->major);
+-
+ 		list_for_each_entry_rcu(e, list, list) {
+-			if ((e->rule.mask[word] & bit) == bit &&
++			if (audit_in_mask(&e->rule, ctx->major) &&
+ 			    audit_filter_rules(tsk, &e->rule, ctx, NULL,
+ 					       &state, false)) {
+ 				rcu_read_unlock();
+@@ -769,20 +782,16 @@ static enum audit_state audit_filter_syscall(struct task_struct *tsk,
+ static int audit_filter_inode_name(struct task_struct *tsk,
+ 				   struct audit_names *n,
+ 				   struct audit_context *ctx) {
+-	int word, bit;
+ 	int h = audit_hash_ino((u32)n->ino);
+ 	struct list_head *list = &audit_inode_hash[h];
+ 	struct audit_entry *e;
+ 	enum audit_state state;
+ 
+-	word = AUDIT_WORD(ctx->major);
+-	bit  = AUDIT_BIT(ctx->major);
+-
+ 	if (list_empty(list))
+ 		return 0;
+ 
+ 	list_for_each_entry_rcu(e, list, list) {
+-		if ((e->rule.mask[word] & bit) == bit &&
++		if (audit_in_mask(&e->rule, ctx->major) &&
+ 		    audit_filter_rules(tsk, &e->rule, ctx, n, &state, false)) {
+ 			ctx->current_state = state;
+ 			return 1;
+-- 
+1.9.0
+
+--
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