From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794062696; b=nu8qoh8T4qJM68iCDt0fTLBYGFkd5E7IX7oi9au+6j0xHfaxuS+5+ghIc8uQffL9nSOK vDlwwoZtTmjC80P4MNYqdhkLel+WziiI+7UdKqVImAtoA1Bwjv8Ng05bP3zsJqQnie9Mi yreBbhn8YxldttXMsl/qe9sV33hXquIn+1zCc5lsujdoOUdRzQFaMxNrQpyUogdoUO2ij dU4p7AndQ293Jrit9PwXFqOb62GzACr0JGw7aOIL9IvFb6dTFSw5WBGEhaYn0gd4FQoBD JHHPmQIdnWqVt62A+pTv5rpVr/Y2wJmMIylIBUrYOzeYyZuL+k8EQGk2pagW50CPAQA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794062696; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=Y1HZgnp1Xx4KkPLzX7faBcRSe0edba7YszpxoM4Nyzo=; b=Czh0oxXKd7gha/hNkcs4vYkZs8gOmuKvWIiEXw8JfmF+KVY/7EJQIYZhNZ0V5XiV+vNX o+PRT+RWTwoApuYZM7urIsSKmpqCRkXJ5dSwOkyZbfntw3jhjsfYmuieCdt2mWgkt/FcO vis7oN/lSuVnmM0zBp0YrdutniovZ6+2atxQc2XDVkYVBnD8HpF1PCpHTyFQ/P/Cg5dvz 2S9/JL9atIjSYKqHCg3F7sdYPwUj8igTl71g6KPY0e21oeTSZs0z+y6vb4nSLmITKYy/C IGLSCMMyedCX8Tg+UJBLn6FURWkddT7YJZdN9h0kRihgUDqYWPGn6JStMdkl6oCPSqg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=fDrCQZhj; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 042E9606A32C; Sat, 7 Nov 2026 14:44:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=fDrCQZhj Received: by smtp.kernel.org (Postfix) with ESMTPSA id A5C601F0089F; Sat, 7 Nov 2026 14:44:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794062695; bh=Y1HZgnp1Xx4KkPLzX7faBcRSe0edba7YszpxoM4Nyzo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=fDrCQZhjKazgQd3eJTGTSrytHaBZxWl4vXaKzWKeA5gdN24ZrvrCuKIXbeglrPCwP ezACYTZ2SuioSpuTlNFQHw61wg7DhPhmafyPqm2xKeXDhsiLig5gtM5JCV3NBiCa09 /uOgA5sawd6DNPBpBPeevZ6XHZPxsRc98iTPxkfc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yuhao Jiang , Zhenhao Wan , Lyude Paul , Sasha Levin Subject: [PATCH 6.18 022/869] drm/nouveau/svm: drain fault handler before freeing svmm Date: Sat, 7 Nov 2026 08:45:04 -0500 Message-ID: <20261107134852.820140450@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261107134852.069646174@linuxfoundation.org> References: <20261107134852.069646174@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zhenhao Wan [ Upstream commit b46ddaf0823405f81e681eb26ec98508f3eb9a07 ] The SVM fault handler nouveau_svm_fault() looks up each fault's nouveau_svmm under svm->mutex, caches it in the fault array, then drops svm->mutex and dereferences the svmm across blocking faults (mmu_interval_notifier_insert(), hmm_range_fault()). nouveau_svmm is not refcounted. On DRM file close nouveau_svmm_fini() -> mmu_notifier_put() frees it asynchronously via call_srcu() without waiting for the handler, and mmget_not_zero() pins the mm, not the svmm. flush_work() on the fault buffer otherwise runs only at device removal and suspend, never on close, so a fault handled concurrently with a close can dereference a freed svmm. The instance is already unlinked by nouveau_svmm_part() earlier in the same close, so no new fault can resolve to it. Drain the handler in nouveau_svmm_fini() before the free, guarding the flush with a NULL check on drm->svm: on device teardown nouveau_svm_fini() runs first and frees drm->svm (NULL) after blocking the notify and flushing the buffer, so the handler is already drained; on per-client close drm->svm is alive and the flush runs. Fixes: eeaf06ac1a55 ("drm/nouveau/svm: initial support for shared virtual memory") Reported-by: Yuhao Jiang Assisted-by: Claude:claude-opus-5 Cc: stable@vger.kernel.org Signed-off-by: Zhenhao Wan Reviewed-by: Lyude Paul Signed-off-by: Lyude Paul Link: https://patch.msgid.link/20260814-nouveau-svm-svmm-uaf-v2-1-8e6590519f07@gmail.com Signed-off-by: Sasha Levin --- drivers/gpu/drm/nouveau/nouveau_svm.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c index 6fa387da06371..dc6c79f57a56d 100644 --- a/drivers/gpu/drm/nouveau/nouveau_svm.c +++ b/drivers/gpu/drm/nouveau/nouveau_svm.c @@ -304,6 +304,19 @@ nouveau_svmm_fini(struct nouveau_svmm **psvmm) { struct nouveau_svmm *svmm = *psvmm; if (svmm) { + struct nouveau_svm *svm = svmm->vmm->cli->drm->svm; + + /* The fault handler caches svmm pointers under svm->mutex and + * dereferences them after dropping it, across blocking faults. + * The instance is already unlinked (nouveau_svmm_part), so drain + * the handler before the free to release any in-flight reference. + * + * On device teardown nouveau_svm_fini() ran first and freed + * drm->svm (NULL) after draining the buffer; nothing to flush. + */ + if (svm) + flush_work(&svm->buffer[0].work); + mutex_lock(&svmm->mutex); svmm->vmm = NULL; mutex_unlock(&svmm->mutex); -- 2.53.0