From: Xiyu Yang xiyuyang19@fudan.edu.cn
commit c6b39f070722ea9963ffe756bfe94e89218c5e63 upstream.
policy_update() invokes begin_current_label_crit_section(), which returns a reference of the updated aa_label object to "label" with increased refcount.
When policy_update() returns, "label" becomes invalid, so the refcount should be decreased to keep refcount balanced.
The reference counting issue happens in one exception handling path of policy_update(). When aa_may_manage_policy() returns not NULL, the refcnt increased by begin_current_label_crit_section() is not decreased, causing a refcnt leak.
Fix this issue by jumping to "end_section" label when aa_may_manage_policy() returns not NULL.
Fixes: 5ac8c355ae00 ("apparmor: allow introspecting the loaded policy pre internal transform") Signed-off-by: Xiyu Yang xiyuyang19@fudan.edu.cn Signed-off-by: Xin Tan tanxin.ctf@gmail.com Signed-off-by: John Johansen john.johansen@canonical.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- security/apparmor/apparmorfs.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c index 280741fc0f5f..f6a3ecfadf80 100644 --- a/security/apparmor/apparmorfs.c +++ b/security/apparmor/apparmorfs.c @@ -454,7 +454,7 @@ static ssize_t policy_update(u32 mask, const char __user *buf, size_t size, */ error = aa_may_manage_policy(label, ns, mask); if (error) - return error; + goto end_section;
data = aa_simple_write_to_buffer(buf, size, size, pos); error = PTR_ERR(data); @@ -462,6 +462,7 @@ static ssize_t policy_update(u32 mask, const char __user *buf, size_t size, error = aa_replace_profiles(ns, label, mask, data); aa_put_loaddata(data); } +end_section: end_current_label_crit_section(label);
return error;