From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 8558013212A; Tue, 4 Feb 2025 06:36:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738650978; cv=none; b=F1ozsssUsrhd0AlWuJwwAzhrIJJo687PV1E0TReEC/mSqL2LU14glzR0SN/yovCc3zFlwpOJZ+ZAjGbyhzoT3Pf4xefcW7MMcJxpqsVVMvWwbmGesCj3d3pgTqCo9MPO9OVkHQu3bAK7QCZkaPA5ZCaf552hHCMzXDyxRVkrLZ8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738650978; c=relaxed/simple; bh=AoPZffDxKXgAYnlcQCovRARbXMgktVy5zIEqbFmvgqE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=c6ZGpVWEplh1mx/1y/LH8yidkh3W0YcOU3c3o76OHlb3bIT3DTm6Pa4hm/mpqeBrR7QzIZXPjKa+pB37IdvoPuBYjPC/kiKT0skHSCDApfQjgbLzn6ihSzR0L3zcrtaQmjAekw01j38WXF4VruOu/Cug5UbOTDlJNdsAOU4qs3E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FmesWUIz; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="FmesWUIz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F2FC5C4CEDF; Tue, 4 Feb 2025 06:36:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1738650978; bh=AoPZffDxKXgAYnlcQCovRARbXMgktVy5zIEqbFmvgqE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=FmesWUIztCVgHs01aJq5nV1qSuwJawTsW6KqDSdGxfhEfhrSDS+f32SAjxB4SA3pz EynFBJLOf6fT+9BHnEKjMmi/DNPNokAjM0EXvTDgDicLkZrSjyBF1YAwyS5ttJAsBP AKs59S9TuYQ8COtxg6DSTYrpKrtcrdaGKDiPDHO9LSuCRFn6nelAswD6mGzF3/mNSd a9CV/naIamDgeaVtS9AKe9a9F6sd1TnQSWVD2LMbKtSMfLfSFjEIdGtEwuk3GywutA HXD13HJ46aHitKCeEW/O4oQlKHYIjvP2f08qDmi5KNJGveTTF+JBenRHTHkQZqmEdZ eaCADCY1zKDlQ== Message-ID: <48ad8f05-a90b-499d-9e73-8e5ff032824a@kernel.org> Date: Tue, 4 Feb 2025 07:36:14 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mtd: Add check and kfree() for kcalloc() To: Christophe JAILLET , Jiasheng Jiang Cc: gmpy.liaowx@gmail.com, kees@kernel.org, linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, miquel.raynal@bootlin.com, richard@nod.at, vigneshr@ti.com, stable@vger.kernel.org References: <30ad77af-4a7b-4a15-9c0b-b0c70d9e1643@wanadoo.fr> <20250204023323.14213-1-jiashengjiangcool@gmail.com> Content-Language: en-US From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 04. 02. 25, 7:17, Christophe JAILLET wrote: > Le 04/02/2025 à 03:33, Jiasheng Jiang a écrit : >> Add a check for kcalloc() to ensure successful allocation. >> Moreover, add kfree() in the error-handling path to prevent memory leaks. >> >> Fixes: 78c08247b9d3 ("mtd: Support kmsg dumper based on pstore/blk") >> Cc: # v5.10+ >> Signed-off-by: Jiasheng Jiang >> --- >> Changelog: >> >> v1 -> v2: >> >> 1. Remove redundant logging. >> 2. Add kfree() in the error-handling path. >> --- >>   drivers/mtd/mtdpstore.c | 19 ++++++++++++++++++- >>   1 file changed, 18 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/mtd/mtdpstore.c b/drivers/mtd/mtdpstore.c >> index 7ac8ac901306..2d8e330dd215 100644 >> --- a/drivers/mtd/mtdpstore.c >> +++ b/drivers/mtd/mtdpstore.c >> @@ -418,10 +418,17 @@ static void mtdpstore_notify_add(struct mtd_info >> *mtd) >>       longcnt = BITS_TO_LONGS(div_u64(mtd->size, info->kmsg_size)); >>       cxt->rmmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL); >> +    if (!cxt->rmmap) >> +        goto end; > > Nitpick: Could be a direct return. > >> + >>       cxt->usedmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL); >> +    if (!cxt->usedmap) >> +        goto free_rmmap; >>       longcnt = BITS_TO_LONGS(div_u64(mtd->size, mtd->erasesize)); >>       cxt->badmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL); >> +    if (!cxt->badmap) >> +        goto free_usedmap; >>       /* just support dmesg right now */ >>       cxt->dev.flags = PSTORE_FLAGS_DMESG; >> @@ -435,10 +442,20 @@ static void mtdpstore_notify_add(struct mtd_info >> *mtd) >>       if (ret) { >>           dev_err(&mtd->dev, "mtd%d register to psblk failed\n", >>                   mtd->index); >> -        return; >> +        goto free_badmap; >>       } >>       cxt->mtd = mtd; >>       dev_info(&mtd->dev, "Attached to MTD device %d\n", mtd->index); >> +    goto end; > > Mater of taste, but I think that having an explicit return here would be > clearer that a goto end; Yes, drop the whole end. >> +free_badmap: >> +    kfree(cxt->badmap); >> +free_usedmap: >> +    kfree(cxt->usedmap); >> +free_rmmap: >> +    kfree(cxt->rmmap); > > I think that in all these paths, you should also have >     cxt->XXXmap = NULL; > after the kfree(). > > otherwise when mtdpstore_notify_remove() is called, you could have a > double free. Right, and this is already a problem for failing register_pstore_device() in _add() -- there is unconditional unregister_pstore_device() in _remove(). Should _remove() check cxt->mtd first? thanks, -- js suse labs