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

It does not work that move the freeing of module.name in audit_free_context Since we should free module.name based on context->types is AUDIT_KERN_MODULE, but __audit_syscall_exit is called first, and will set context->type to 0, When audit_free_context is called, context->type is 0, will cause to fail. I will change this patches as below: commit ee32ec2354b47a824e5e63d4f46567d577a02824 (HEAD -> master) Author: Li RongQing <lirongqing(a)baidu.com&gt; Date: Tue Mar 5 15:42:09 2019 +0800 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 released so always free module.name in audit_free_context 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; diff --git a/kernel/auditsc.c b/kernel/auditsc.c index b2d1f043f..07728b07a 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -964,6 +964,9 @@ int audit_alloc(struct task_struct *tsk) static inline void audit_free_context(struct audit_context *context) { + if (context->type == AUDIT_KERN_MODULE) + kfree(context->module.name); + audit_free_names(context); unroll_tree_refs(context, NULL, 0); free_tree_refs(context); @@ -1282,6 +1285,8 @@ static void show_special(struct audit_context *context, int *call_panic) if (context->module.name) { audit_log_untrustedstring(ab, context->module.name); kfree(context->module.name); + context->module.name = NULL; + context->type = 0; } else audit_log_format(ab, "(null)"); @@ -1583,6 +1588,11 @@ void __audit_syscall_exit(int success, long return_code) if (!list_empty(&context->killed_trees)) audit_kill_trees(&context->killed_trees); + if (context->type == AUDIT_KERN_MODULE) { + kfree(context->module.name); + context->module.name = NULL; + } + audit_free_names(context); unroll_tree_refs(context, NULL, 0); audit_free_aux(context); -RongQing