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=1793211527; b=ot1OU6Hnweiwby8BOPSlhjdHygoAmk1s4Cah2bXf3IYndzT8i9O9PS+mxYAqpce2vq89 BGAF0zZ5WmNgidJ3MMxjnFFvYo0iPm/WYf5G5fyQcknU3Afx0jSkQEBczG4NSK9x3mnhh VIi9w/HrpB3kV1tN7XP9+TTwL6tjYi033fzTLmql29tz5PI1UJfaOGWW/z0DDBwynjFDA kAT0AnqYqsmaT9DDYjbh4O7ULjdBQOQNup2YH7EAHLa/xR4aB2arQq6NCfk5PD7Kelplh BRGfR8Pi+vk15fQSDgZlYsd83NAybmKHL7nDjON/xlRjfQvoQ9ld4j+JuiRFY/QpDCA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793211527; 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=5Gs+JzZRYI3BmdS9Slg+MFYG+dJ8wPvdIggV9Fv0yFs=; b=Dqc9KIQtQM4LSPJW1p8qlt5QoMKEaRClIqwuHLcmYBxEgm6kxRSYHsJWGPkKTyhfPGkX HuhVw5DJm9WQGdGdlYwNTdJjeRdblSZuIfRLPbTsFtShHKILL+orpTttthaoS4QSj9wJO dmn5IxtYxGVpKFUirSW3f1/qs7UcX5PBrCWkhSQxZ3y88adbZ4y4IGGPMSXX5ojh2+v9j OnVBP5/OdpDRnE58p+6AGLr5K2inkU4QAHFJYdREdrrcLcpLi29yzwRf+8DV+hK4vN3V6 LM4zWt8W2EAXWf4AtwkQITw6QoSvt38S1mRQ9wmZ35tsuxKPsStMDqER3H5XOuX+9IA== 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=ziV2SI3G; 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 64D78606A31D; Wed, 28 Oct 2026 18:18:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=ziV2SI3G Received: by smtp.kernel.org (Postfix) with ESMTPSA id B60AD1F01825; Wed, 28 Oct 2026 18:18:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793211527; bh=5Gs+JzZRYI3BmdS9Slg+MFYG+dJ8wPvdIggV9Fv0yFs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ziV2SI3GTIvWI+FercCgX0Wau03AaU175Rea8128EP7ytExIwq8ODd+bny4Q7gotg PuwKVONPcJXM4Ct1xoiQj+auD7ZhoBZ524qFxeIdZdBEGEGu76w9Qn9QWYw5V2wDkE NaUG4evgVNfb5OSy5VWUBCcVmwY0uVDpu9hAxmFE= 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 Subject: [PATCH 5.15 407/571] mtd: fix double free and WARN_ON in add_mtd_device() error paths Date: Wed, 28 Oct 2026 17:59:14 +0100 Message-ID: <20261028170017.670119715@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170008.009143722@linuxfoundation.org> References: <20261028170008.009143722@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xue Lei commit 9d4af746af8ce27eefc2338b2feaa1e01f28b6c3 upstream. 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: Greg Kroah-Hartman --- drivers/mtd/mtdcore.c | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-) --- a/drivers/mtd/mtdcore.c +++ b/drivers/mtd/mtdcore.c @@ -102,6 +102,15 @@ static void mtd_release(struct device *d 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); @@ -700,10 +709,8 @@ int add_mtd_device(struct mtd_info *mtd) dev_set_drvdata(&mtd->dev, 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); @@ -730,8 +737,16 @@ 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: