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Date: Thu, 15 Nov 2012 18:57:20 -0800
From: Kees Cook <keescook@...omium.org>
To: linux-kernel@...r.kernel.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Al Viro <viro@...iv.linux.org.uk>,
Eric Paris <eparis@...hat.com>
Subject: [PATCH] audit: catch possible NULL buffers
It's possible for audit_log_start() to return NULL. Handle it in various
callers.
Cc: stable@...r.kernel.org
Signed-off-by: Kees Cook <keescook@...omium.org>
---
kernel/audit.c | 4 ++++
kernel/audit_tree.c | 26 +++++++++++++++++---------
kernel/audit_watch.c | 2 ++
kernel/auditsc.c | 8 ++++++--
4 files changed, 29 insertions(+), 11 deletions(-)
diff --git a/kernel/audit.c b/kernel/audit.c
index 40414e9..a219998 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -272,6 +272,8 @@ static int audit_log_config_change(char *function_name, int new, int old,
int rc = 0;
ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
+ if (unlikely(!ab))
+ return rc;
audit_log_format(ab, "%s=%d old=%d auid=%u ses=%u", function_name, new,
old, from_kuid(&init_user_ns, loginuid), sessionid);
if (sid) {
@@ -619,6 +621,8 @@ static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type,
}
*ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
+ if (unlikely(!*ab))
+ return rc;
audit_log_format(*ab, "pid=%d uid=%u auid=%u ses=%u",
task_tgid_vnr(current),
from_kuid(&init_user_ns, current_uid()),
diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
index ed206fd..29dc061 100644
--- a/kernel/audit_tree.c
+++ b/kernel/audit_tree.c
@@ -449,11 +449,26 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
return 0;
}
+static void audit_log_remove_rule(struct audit_krule *rule)
+{
+ struct audit_buffer *ab;
+
+ ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
+ if (unlikely(!ab))
+ return;
+ audit_log_format(ab, "op=");
+ audit_log_string(ab, "remove rule");
+ audit_log_format(ab, " dir=");
+ audit_log_untrustedstring(ab, rule->tree->pathname);
+ audit_log_key(ab, rule->filterkey);
+ audit_log_format(ab, " list=%d res=1", rule->listnr);
+ audit_log_end(ab);
+}
+
static void kill_rules(struct audit_tree *tree)
{
struct audit_krule *rule, *next;
struct audit_entry *entry;
- struct audit_buffer *ab;
list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
entry = container_of(rule, struct audit_entry, rule);
@@ -461,14 +476,7 @@ static void kill_rules(struct audit_tree *tree)
list_del_init(&rule->rlist);
if (rule->tree) {
/* not a half-baked one */
- ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
- audit_log_format(ab, "op=");
- audit_log_string(ab, "remove rule");
- audit_log_format(ab, " dir=");
- audit_log_untrustedstring(ab, rule->tree->pathname);
- audit_log_key(ab, rule->filterkey);
- audit_log_format(ab, " list=%d res=1", rule->listnr);
- audit_log_end(ab);
+ audit_log_remove_rule(rule);
rule->tree = NULL;
list_del_rcu(&entry->list);
list_del(&entry->rule.list);
diff --git a/kernel/audit_watch.c b/kernel/audit_watch.c
index 9a9ae6e..3e29b7a 100644
--- a/kernel/audit_watch.c
+++ b/kernel/audit_watch.c
@@ -240,6 +240,8 @@ static void audit_watch_log_rule_change(struct audit_krule *r, struct audit_watc
if (audit_enabled) {
struct audit_buffer *ab;
ab = audit_log_start(NULL, GFP_NOFS, AUDIT_CONFIG_CHANGE);
+ if (unlikely(!ab))
+ return;
audit_log_format(ab, "auid=%u ses=%u op=",
from_kuid(&init_user_ns, audit_get_loginuid(current)),
audit_get_sessionid(current));
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 2f186ed..9a836b8 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1481,14 +1481,14 @@ static void show_special(struct audit_context *context, int *call_panic)
audit_log_end(ab);
ab = audit_log_start(context, GFP_KERNEL,
AUDIT_IPC_SET_PERM);
+ if (unlikely(!ab))
+ return;
audit_log_format(ab,
"qbytes=%lx ouid=%u ogid=%u mode=%#ho",
context->ipc.qbytes,
context->ipc.perm_uid,
context->ipc.perm_gid,
context->ipc.perm_mode);
- if (!ab)
- return;
}
break; }
case AUDIT_MQ_OPEN: {
@@ -2775,6 +2775,8 @@ void audit_core_dumps(long signr)
return;
ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_ANOM_ABEND);
+ if (unlikely(!ab))
+ return;
audit_log_abend(ab, "memory violation", signr);
audit_log_end(ab);
}
@@ -2784,6 +2786,8 @@ void __audit_seccomp(unsigned long syscall, long signr, int code)
struct audit_buffer *ab;
ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_ANOM_ABEND);
+ if (unlikely(!ab))
+ return;
audit_log_abend(ab, "seccomp", signr);
audit_log_format(ab, " syscall=%ld", syscall);
audit_log_format(ab, " compat=%d", is_compat_task());
--
1.7.9.5
--
Kees Cook
Chrome OS Security
--
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