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Wed, 24 Dec 2025 15:54:16 -0800 (PST) Received: from prometheus ([85.11.110.37]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b8037f0b7bcsm1972149266b.49.2025.12.24.15.54.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Dec 2025 15:54:16 -0800 (PST) From: Szymon Wilczek To: Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz Cc: linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+4d6b203d625d2f57d4ca@syzkaller.appspotmail.com, Szymon Wilczek Subject: [PATCH] Bluetooth: hci_core: Fix slab-use-after-free in hci_cmd_work Date: Thu, 25 Dec 2025 00:54:07 +0100 Message-ID: <20251224235407.46333-1-swilczek.lx@gmail.com> X-Mailer: git-send-email 2.52.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" syzbot reported a slab-use-after-free in hci_cmd_work. The issue is that hci_send_cmd_sync() consumes the skb reference (either by passing it to the driver which frees it, or by calling kfree_skb() on error), but the skb might be accessed after the call in certain configurations or due to race conditions with the freeing process (e.g. vhci_read). Explicitly hold a reference to the skb using skb_get() before calling hci_send_cmd_sync() and release it with kfree_skb() afterwards. This ensures the skb object remains valid throughout the function call, regardless of how hci_send_cmd_sync() handles the original reference. Reported-by: syzbot+4d6b203d625d2f57d4ca@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3D4d6b203d625d2f57d4ca Signed-off-by: Szymon Wilczek --- net/bluetooth/hci_core.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c index 8ccec73dce45..af4ef31295c4 100644 --- a/net/bluetooth/hci_core.c +++ b/net/bluetooth/hci_core.c @@ -4149,7 +4149,10 @@ static void hci_cmd_work(struct work_struct *work) if (!skb) return; =20 + skb_get(skb); err =3D hci_send_cmd_sync(hdev, skb); + kfree_skb(skb); + if (err) return; =20 --=20 2.52.0