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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 9/18/26 01:24, Greg KH wrote: > On Thu, Sep 17, 2026 at 01:18:20PM -0700, John Johansen wrote: >> On 9/17/26 12:19, Ryan Lee wrote: >>> On Thu, Sep 17, 2026 at 11:59 AM Wentao Liang wrote: >>>> >>>> The inner block in aa_unix_file_perm() re-declares plabel, shadowing the >>>> outer variable that is released at the out label. The reference taken by >>>> aa_get_label_rcu() is thus lost when the block exits, and aa_put_label() >>>> at out is a no-op on the still NULL outer plabel, leaking one label per >>>> permission check on a non-filesystem unix socket. >>>> >>>> Drop the shadowing declaration so the outer plabel is used and released. >>>> >>>> Fixes: 88fec3526e84 ("apparmor: make sure unix socket labeling is correctly updated.") >>>> Cc: stable@vger.kernel.org >>>> Signed-off-by: Wentao Liang >>>> --- >>>> security/apparmor/af_unix.c | 1 - >>>> 1 file changed, 1 deletion(-) >>>> >>>> diff --git a/security/apparmor/af_unix.c b/security/apparmor/af_unix.c >>>> index fdb4a9f212c3..ecb40cfe7e14 100644 >>>> --- a/security/apparmor/af_unix.c >>>> +++ b/security/apparmor/af_unix.c >>>> @@ -758,7 +758,6 @@ int aa_unix_file_perm(const struct cred *subj_cred, struct aa_label *label, >>>> unix_fs_perm(op, request, subj_cred, label, >>>> is_unix_fs(peer_sk) ? &peer_path : NULL)); >>>> } else if (!is_sk_fs) { >>>> - struct aa_label *plabel; >>>> struct aa_sk_ctx *pctx = aa_sock(peer_sk); >>>> >>>> rcu_read_lock(); >>>> -- >>>> 2.34.1 >>>> >>>> >>> >>> NACK: this exact patch has been proposed before, and unfortunately >>> exposes an additional latent bug around plabel handling that results >>> in a use-after-free if the shadowed declaration is removed without >>> additional fixes. >>> >>> I can try to dig out the relevant exchange from the AppArmor mailing >>> list later, if you'd be interested. >>> >> The series Ryan is referring to is in Linus's tree, so you should see the >> fix rolling out to stable kernels as well soon. >> >> 6d25e7b47616c apparmor: fix refcount leak when updating the sk_ctx >> b1aea2c196077 apparmor: fix race in unix socket mediation when peer_path is used >> 4483efe4f2151 apparmor: fix shadowing of plabel that prevents cache from being updated > > These are all in stable released kernels already for many weeks, so how > is any of this still being reported? > > confused, > I don't know, my guess is either using a distro kernel, or not having updated to a newer stable kernel. I should not have said "stable", I should have said in updated kernels.