From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3863643FD01; Thu, 30 Jul 2026 15:58:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785427088; cv=none; b=aLqURoo3Bwy9m32DJt2aRaVEWvt5jfiTWHrVtGmWBl7CdxvRhSddBPwDM3QU+r8jE2ysq56tT/osQfuVuq2pswHTlMC89ZXmJynsRx2p+LCfmy9ga5O9XnRCuHBfcrOKXAA5lvYd/KqPN5xbtjWMg0TB+DLCgdkPh/h2PPd4XoM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785427088; c=relaxed/simple; bh=2sgxrekKWIHTdATIfomlWPtW/GBLzkbL3hKec9QGB3Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bkoiU80mwmqdyscL8TD5UE0ith17L4xKKFz4A8AJXWUhH8SUBOtQwpcqD6UCHZiGA2j+i+uABnn0J/NiYcyyQV44dJcTvzDyt8GLPoNUqvFMUSPvApxlB/mMJWB++poFRMLdVs/8Y8WlF7PLzLKTodbI+g8e/foaXluflyz9sgo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=FPGEVKhV; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="FPGEVKhV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 949EF1F00A3A; Thu, 30 Jul 2026 15:58:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785427087; bh=6oJ01fle18pIs6tCQ5H7Yb9uZfIFmAohUPzp5gfhiBI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=FPGEVKhVaaESQJurlNF/gRjDPV2H09xwG0TRSGa+L8KyNs68ZyfhQzhSsSD6uVtVl 7uREpjFDuW4iQV+4hc4IFDrsOgCxUM/qXmJQoaTC0IycBSI1Svv7ugxhJavpITzqqr O4ENwqn4oL3N9hLw/4vOjUTWqh61DvkzyiPUdOgk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+e9c76b56dc05023b8117@syzkaller.appspotmail.com, Xue Lei , Miquel Raynal , Sasha Levin Subject: [PATCH 6.6 048/484] mtd: fix double free and WARN_ON in add_mtd_device() error paths Date: Thu, 30 Jul 2026 16:09:05 +0200 Message-ID: <20260730141424.467337911@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141423.392222816@linuxfoundation.org> References: <20260730141423.392222816@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xue Lei [ Upstream commit 9d4af746af8ce27eefc2338b2feaa1e01f28b6c3 ] When device_register() or mtd_nvmem_add() fails inside add_mtd_device() for a partition, the error handling triggers mtd_release() via put_device() or device_unregister(). mtd_release() calls release_mtd_partition() which frees the mtd_info structure. However, callers such as mtd_add_partition() and add_mtd_partitions() also call free_partition() in their error paths, resulting in a double free. Additionally, release_mtd_partition() hits WARN_ON(!list_empty( &mtd->part.node)) because the partition node is still linked in the parent's partitions list when the release callback fires from the add_mtd_device() error path. Fix this by overriding dev->type and dev->release before put_device() in the error paths, so that device_release() invokes a no-op function instead of mtd_release(). For the mtd_nvmem_add() failure case, device_unregister() is replaced with device_del() to separate the device removal from the final kobject reference drop, allowing the override to take effect before put_device() is called. The callers' error paths (list_del + free_partition) remain the sole owners of mtd_info lifetime on add_mtd_device() failure, which is the expected contract. The normal partition teardown path is not affected: del_mtd_device() goes through kref_put() -> mtd_device_release() -> device_unregister() with dev->type still set to &mtd_devtype, so mtd_release() -> release_mtd_partition() continues to work correctly for the regular removal case. Reported-by: syzbot+e9c76b56dc05023b8117@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=e9c76b56dc05023b8117 Fixes: 19bfa9ebebb5 ("mtd: use refcount to prevent corruption") Signed-off-by: Xue Lei Signed-off-by: Miquel Raynal Signed-off-by: Sasha Levin --- drivers/mtd/mtdcore.c | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-) diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c index 97ca2a897f1d49..506ebd4ba1b458 100644 --- a/drivers/mtd/mtdcore.c +++ b/drivers/mtd/mtdcore.c @@ -103,6 +103,15 @@ static void mtd_release(struct device *dev) device_destroy(&mtd_class, index + 1); } +/* + * No-op device release used in add_mtd_device() error paths. + * Prevents mtd_release() from being called via device_release(), + * which would free the mtd_info that the caller still manages. + */ +static void mtd_dev_release_nop(struct device *dev) +{ +} + static void mtd_device_release(struct kref *kref) { struct mtd_info *mtd = container_of(kref, struct mtd_info, refcnt); @@ -745,10 +754,8 @@ int add_mtd_device(struct mtd_info *mtd) mtd_check_of_node(mtd); of_node_get(mtd_get_of_node(mtd)); error = device_register(&mtd->dev); - if (error) { - put_device(&mtd->dev); + if (error) goto fail_added; - } /* Add the nvmem provider */ error = mtd_nvmem_add(mtd); @@ -786,8 +793,16 @@ int add_mtd_device(struct mtd_info *mtd) return 0; fail_nvmem_add: - device_unregister(&mtd->dev); + device_del(&mtd->dev); fail_added: + /* + * Clear type and set nop release to prevent mtd_release() -> + * release_mtd_partition() -> free_partition() from freeing mtd. + * The caller handles cleanup on failure. + */ + mtd->dev.type = NULL; + mtd->dev.release = mtd_dev_release_nop; + put_device(&mtd->dev); of_node_put(mtd_get_of_node(mtd)); idr_remove(&mtd_idr, i); fail_locked: -- 2.53.0