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([41.249.127.205]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4922032ae56sm165261205e9.7.2026.06.14.08.00.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 14 Jun 2026 08:00:45 -0700 (PDT) From: Mohammed EL Kadiri To: dhowells@redhat.com, jarkko@kernel.org, paul@paul-moore.com Cc: jmorris@namei.org, serge@hallyn.com, ebiggers@google.com, keyrings@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, syzkaller-bugs@googlegroups.com, Mohammed EL Kadiri , syzbot+f55b043dacf43776b50c@syzkaller.appspotmail.com Subject: [PATCH] KEYS: avoid filesystem reclaim while holding keyring->sem Date: Sun, 14 Jun 2026 16:00:41 +0100 Message-ID: <20260614150041.21172-1-med08elkadiri@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit __key_link_begin() runs with keyring->sem held and calls assoc_array_insert(), which does GFP_KERNEL allocations. Those allocations may enter filesystem reclaim, evict an fscrypt-protected inode, and reach keyring_clear() via fscrypt_put_master_key() -- taking a keyring semaphore of the same lockdep class and closing a keyring->sem -> fs_reclaim -> keyring->sem cycle reported by syzbot. Wrap the assoc_array_insert() call with memalloc_nofs_save() / memalloc_nofs_restore() so reclaim cannot recurse into the keys subsystem while keyring->sem is held. Reported-by: syzbot+f55b043dacf43776b50c@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=f55b043dacf43776b50c Fixes: d7e7b9af104c ("fscrypt: stop using keyrings subsystem for fscrypt_master_key") Cc: stable@vger.kernel.org Signed-off-by: Mohammed EL Kadiri --- security/keys/keyring.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/security/keys/keyring.c b/security/keys/keyring.c index 5a9887d6b7be..21bb2e7e7cca 100644 --- a/security/keys/keyring.c +++ b/security/keys/keyring.c @@ -12,6 +12,7 @@ #include #include #include +#include #include #include #include @@ -1298,6 +1299,7 @@ int __key_link_begin(struct key *keyring, struct assoc_array_edit **_edit) { struct assoc_array_edit *edit; + unsigned int nofs_flags; int ret; kenter("%d,%s,%s,", @@ -1315,10 +1317,12 @@ int __key_link_begin(struct key *keyring, /* Create an edit script that will insert/replace the key in the * keyring tree. */ + nofs_flags = memalloc_nofs_save(); edit = assoc_array_insert(&keyring->keys, &keyring_assoc_array_ops, index_key, NULL); + memalloc_nofs_restore(nofs_flags); if (IS_ERR(edit)) { ret = PTR_ERR(edit); goto error; -- 2.43.0