Re: [PATCH][v3] audit: fix a memleak caused by auditing load module

module.name will be allocated unconditionally when auditing load module, and audit_log_start() can fail with other reasons, or audit_log_exit maybe not called, caused module.name is not freed so free module.name in audit_free_context and __audit_syscall_exit 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(a)baidu.com&gt; Signed-off-by: Li RongQing <lirongqing(a)baidu.com&gt; --- v3-->v2: create a helper and git rid of free from show_special as Paul suggest v2-->v1: free module.name always, not check the return of audit_log_start kernel/auditsc.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/kernel/auditsc.c b/kernel/auditsc.c index b2d1f043f..001056b4c 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -881,6 +881,13 @@ static inline void audit_proctitle_free(struct audit_context *context) context->proctitle.len = 0; } +static inline void audit_free_module(struct audit_context *context) +{ + if (context->type == AUDIT_KERN_MODULE) { + kfree(context->module.name); + context->module.name = NULL; + } +} static inline void audit_free_names(struct audit_context *context) { struct audit_names *n, *next; @@ -964,6 +971,7 @@ int audit_alloc(struct task_struct *tsk) static inline void audit_free_context(struct audit_context *context) { + audit_free_module(context); audit_free_names(context); unroll_tree_refs(context, NULL, 0); free_tree_refs(context); @@ -1281,7 +1289,6 @@ static void show_special(struct audit_context *context, int *call_panic) audit_log_format(ab, "name="); if (context->module.name) { audit_log_untrustedstring(ab, context->module.name); - kfree(context->module.name); } else audit_log_format(ab, "(null)"); @@ -1583,6 +1590,7 @@ void __audit_syscall_exit(int success, long return_code) if (!list_empty(&context->killed_trees)) audit_kill_trees(&context->killed_trees); + audit_free_module(context); audit_free_names(context); unroll_tree_refs(context, NULL, 0); audit_free_aux(context); -- 2.16.2