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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, chenzefeng <chenzefeng2@huawei.com>,
        Tony Luck <tony.luck@intel.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.4 48/99] ia64:unwind: fix double free for mod->arch.init_unw_table
Date:   Thu,  3 Oct 2019 17:53:11 +0200
Message-Id: <20191003154318.587383181@linuxfoundation.org>
In-Reply-To: <20191003154252.297991283@linuxfoundation.org>
References: <20191003154252.297991283@linuxfoundation.org>
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From: chenzefeng <chenzefeng2@huawei.com>

[ Upstream commit c5e5c48c16422521d363c33cfb0dcf58f88c119b ]

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@huawei.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 36b2c94a8eb5d..14c7184daaf64 100644
--- a/arch/ia64/kernel/module.c
+++ b/arch/ia64/kernel/module.c
@@ -912,8 +912,12 @@ module_finalize (const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, struct module *mo
 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;
+	}
 }
-- 
2.20.1