[PATCH] security: tomoyo: fix error return code of tomoyo_update_domain()

[PATCH] security: tomoyo: fix error return code of tomoyo_update_domain()

[Jia-Ju Bai]

When mutex_lock_interruptible() fails, the error return code of
tomoyo_update_domain() is not properly assigned.
To fix this bug, error is assigned with the return value of
mutex_lock_interruptible(), and then error is checked.

Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
---
 security/tomoyo/domain.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c
index 98d985895ec8..7b9f9664dbe3 100644
--- a/security/tomoyo/domain.c
+++ b/security/tomoyo/domain.c
@@ -118,7 +118,8 @@ int tomoyo_update_domain(struct tomoyo_acl_info *new_entry, const int size,
 		      ->perm == 1 << TOMOYO_TYPE_EXECUTE))
 			goto out;
 	}
-	if (mutex_lock_interruptible(&tomoyo_policy_lock))
+	error = mutex_lock_interruptible(&tomoyo_policy_lock);
+	if (error)
 		goto out;
 	list_for_each_entry_rcu(entry, list, list,
 				srcu_read_lock_held(&tomoyo_ss)) {
-- 
2.17.1

Re: [PATCH] security: tomoyo: fix error return code of tomoyo_update_domain()

[Tetsuo Handa]

On 2021/03/06 22:03, Jia-Ju Bai wrote:
> When mutex_lock_interruptible() fails, the error return code of
> tomoyo_update_domain() is not properly assigned.
> To fix this bug, error is assigned with the return value of
> mutex_lock_interruptible(), and then error is checked.

Thanks for a patch, but this patch is wrong.
Since the variable "error" is initialized as

  int error = is_delete ? -ENOENT : -ENOMEM;

at the beginning of this function, unconditionally overwriting
this variable with the return code of mutex_lock_interruptible() breaks

  if (error && !is_delete) {
  }

block of this function.

And the caller does not check if the return code is -EINTR
instead of -ENOENT or -ENOMEM.