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Subject[PATCH] audit: fix a memleak caused by auditing load module
Date
we should always free context->module.name, since it will be
allocated unconditionally and audit_log_start() can fail with
other reasons, and audit_log_exit maybe not called

unreferenced object 0xffff88af90837d20 (size 8):
comm "modprobe", pid 1036, jiffies 4294704867 (age 3069.138s)
hex dump (first 8 bytes):
69 78 67 62 65 00 ff ff ixgbe...
backtrace:
[<0000000008da28fe>] __audit_log_kern_module+0x33/0x80
[<00000000c1491e61>] load_module+0x64f/0x3850
[<000000007fc9ae3f>] __do_sys_init_module+0x218/0x250
[<0000000000d4a478>] do_syscall_64+0x117/0x400
[<000000004924ded8>] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[<000000007dc331dd>] 0xffffffffffffffff

Fixes: ca86cad7380e3 ("audit: log module name on init_module")
Signed-off-by: Zhang Yu <zhangyu31@baidu.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
---
kernel/auditsc.c | 22 ++++++++++++++++++++--
1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index b2d1f043f..2bd80375f 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1186,8 +1186,13 @@ static void show_special(struct audit_context *context, int *call_panic)
int i;

ab = audit_log_start(context, GFP_KERNEL, context->type);
- if (!ab)
+ if (!ab) {
+ if (context->type == AUDIT_KERN_MODULE) {
+ kfree(context->module.name);
+ context->module.name = NULL;
+ }
return;
+ }

switch (context->type) {
case AUDIT_SOCKETCALL: {
@@ -1354,8 +1359,15 @@ static void audit_log_exit(struct audit_context *context, struct task_struct *ts
context->personality = tsk->personality;

ab = audit_log_start(context, GFP_KERNEL, AUDIT_SYSCALL);
- if (!ab)
+
+ if (!ab) {
+ if (context->type == AUDIT_KERN_MODULE) {
+ kfree(context->module.name);
+ context->module.name = NULL;
+ }
return; /* audit_panic has been called */
+ }
+
audit_log_format(ab, "arch=%x syscall=%d",
context->arch, context->major);
if (context->personality != PER_LINUX)
@@ -1576,6 +1588,12 @@ void __audit_syscall_exit(int success, long return_code)

if (context->in_syscall && context->current_state == AUDIT_RECORD_CONTEXT)
audit_log_exit(context, current);
+ else {
+ if (context->type == AUDIT_KERN_MODULE) {
+ kfree(context->module.name);
+ context->module.name = NULL;
+ }
+ }

context->in_syscall = 0;
context->prio = context->state == AUDIT_RECORD_CONTEXT ? ~0ULL : 0;
--
2.16.2
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