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

[Jiri Slaby]

From: Andy Lutomirski <luto@xxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxx # v3.16
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 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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