linux-kernel - [PATCH] ia64:unwind: fix double free for mod->arch.init_unw

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Date:   Tue, 6 Aug 2019 15:46:33 +0800
From:   chenzefeng <chenzefeng2@...wei.com>
To:     <tony.luck@...el.com>, <fenghua.yu@...el.com>,
        <chenzefeng2@...wei.com>
CC:     <linux-ia64@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <stable@...r.kernel.org>
Subject: [PATCH] ia64:unwind: fix double free for mod->arch.init_unw_table

The function free_module in file kernel/module.c as follow:

void free_module(struct module *mod) {
	......
	module_arch_cleanup(mod);
	......
	module_arch_freeing_init(mod);
	......
}

Both module_arch_cleanup and module_arch_freeing_init function
would free the mod->arch.init_unw_table, which cause double free.

Here, set mod->arch.init_unw_table = NULL after remove the unwind
table to avoid double free.

Signed-off-by: chenzefeng <chenzefeng2@...wei.com>
---
 arch/ia64/kernel/module.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/ia64/kernel/module.c b/arch/ia64/kernel/module.c
index 326448f..1a42ba8 100644
--- a/arch/ia64/kernel/module.c
+++ b/arch/ia64/kernel/module.c
@@ -914,10 +914,14 @@ struct plt_entry {
 void
 module_arch_cleanup (struct module *mod)
 {
-	if (mod->arch.init_unw_table)
+	if (mod->arch.init_unw_table) {
 		unw_remove_unwind_table(mod->arch.init_unw_table);
-	if (mod->arch.core_unw_table)
+		mod->arch.init_unw_table = NULL;
+	}
+	if (mod->arch.core_unw_table) {
 		unw_remove_unwind_table(mod->arch.core_unw_table);
+		mod->arch.core_unw_table = NULL;
+	}
 }
 
 void *dereference_module_function_descriptor(struct module *mod, void *ptr)
-- 
1.8.5.6