linux-kernel - [PATCH 3.12 114/155] module: Clean up ro/nx after early module load failures

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Date:	Tue,  7 Apr 2015 14:51:23 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org,
	Andy Lutomirski <luto@...capital.net>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 114/155] module: Clean up ro/nx after early module load failures

From: Andy Lutomirski <luto@...capital.net>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit ff7e0055bb5ddbbb320cdd8dfd3e18672bddd2ad upstream.

The commit

    4982223e51e8 module: set nx before marking module MODULE_STATE_COMING.

introduced a regression: if a module fails to parse its arguments or
if mod_sysfs_setup fails, then the module's memory will be freed
while still read-only.  Anything that reuses that memory will crash
as soon as it tries to write to it.

Cc: stable@...r.kernel.org # v3.16
Cc: Rusty Russell <rusty@...tcorp.com.au>
Signed-off-by: Andy Lutomirski <luto@...capital.net>
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 kernel/module.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/module.c b/kernel/module.c
index 3edb91fabc7a..a97785308f25 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3332,6 +3332,11 @@ static int load_module(struct load_info *info, const char __user *uargs,
 	mutex_lock(&module_mutex);
 	module_bug_cleanup(mod);
 	mutex_unlock(&module_mutex);
+
+	/* we can't deallocate the module until we clear memory protection */
+	unset_module_init_ro_nx(mod);
+	unset_module_core_ro_nx(mod);
+
  ddebug_cleanup:
 	dynamic_debug_remove(info->debug);
 	synchronize_sched();
-- 
2.3.4

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