From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.nfschina.com (unknown [42.101.60.213]) by smtp.subspace.kernel.org (Postfix) with SMTP id 2700E54738; Tue, 15 Oct 2024 01:47:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=42.101.60.213 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728956860; cv=none; b=Jm6bXHiZSIe5mbi+hLcMx10mP/YZdOOTjJQLx+aV0g3XgGqqz/tH6hXRW4vlIM6lTALivDB4FNsUJdCrbTR7M+ZzpFXlv/BKkXnXgoVAffv6JvV4vh/aLpeg1e9kmyu/q6hMk66gO0wOgROEdKg3XAy8mqSuxT/8fOgZ7ZZ2M6k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728956860; c=relaxed/simple; bh=mKuzTgXZ5SrzCglC2W7yV36DIGk73UAm3Drpg1dOslg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:From:In-Reply-To: Content-Type; b=PMm72HaRfKfPUGf6GwLWZ9tsn4f8iFQiztAHad4uMXEGVdN2slI8g9aFWtgbIrqeq+Oz/MFvwWVFpMK7CLHdNZ/X3ezhtOijX0yOUuVfZ/tlGCnl2nK/ZuF4CCeyw820wAcpeyaRaFe4MLr5/5NO/jao/eOjx9MwD3KDxxaLrd0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=nfschina.com; spf=pass smtp.mailfrom=nfschina.com; arc=none smtp.client-ip=42.101.60.213 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=nfschina.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=nfschina.com Received: from [172.30.20.101] (unknown [180.167.10.98]) by mail.nfschina.com (MailData Gateway V2.8.8) with ESMTPSA id 7E0A760BFCF20; Tue, 15 Oct 2024 09:47:29 +0800 (CST) Message-ID: <725540a7-b3ab-d116-8410-8fe077e008c7@nfschina.com> Date: Tue, 15 Oct 2024 09:47:28 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.1 Subject: Re: [PATCH] smb: client: fix possible double free in smb2_set_ea() To: Dan Carpenter Cc: sfrench@samba.org, pc@manguebit.com, ronniesahlberg@gmail.com, sprasad@microsoft.com, stfrench@microsoft.com, tom@talpey.com, bharathsm@microsoft.com, nathan@kernel.org, ndesaulniers@google.com, morbo@google.com, justinstitt@google.com, linux-cifs@vger.kernel.org, samba-technical@lists.samba.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, kernel-janitors@vger.kernel.org Content-Language: en-US X-MD-Sfrom: suhui@nfschina.com X-MD-SrcIP: 180.167.10.98 From: Su Hui In-Reply-To: <8bd0fae3-82fe-41c4-a4e8-3c28aa2b1826@stanley.mountain> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2024/10/14 20:53, Dan Carpenter wrote: > On Mon, Oct 14, 2024 at 07:34:17PM +0800, Su Hui wrote: >> Clang static checker(scan-build) warning： >> fs/smb/client/smb2ops.c:1304:2: Attempt to free released memory. >> 1304 | kfree(ea); >> | ^~~~~~~~~ >> >> There is a double free in such case: >> 'ea is initialized to NULL' -> 'first successful memory allocation for >> ea' -> 'something failed, goto sea_exit' -> 'first memory release for ea' >> -> 'goto replay_again' -> 'second goto sea_exit before allocate memory >> for ea' -> 'second memory release for ea resulted in double free'. >> >> Assign NULL value to 'ea' after 'kfree(ea)', it can fix this double free >> problem. >> >> Fixes: 4f1fffa23769 ("cifs: commands that are retried should have replay flag set") >> Signed-off-by: Su Hui >> --- >> fs/smb/client/smb2ops.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c >> index 6b385fce3f2a..5b42b352b703 100644 >> --- a/fs/smb/client/smb2ops.c >> +++ b/fs/smb/client/smb2ops.c >> @@ -1302,6 +1302,7 @@ smb2_set_ea(const unsigned int xid, struct cifs_tcon *tcon, >> >> sea_exit: >> kfree(ea); >> + ea = NULL; > That's very clever. But I think that it would be better to do the "ea = NULL" > near to the replay_again label. There are some lines where we re-initialize > resp_buftype[], utf16_path and vars etc. > > ea = NULL; > resp_buftype[0] = resp_buftype[1] = resp_buftype[2] = CIFS_NO_BUFFER; Yes, it's better! Thanks for your suggestions. I will send v2 patch soon. Su Hui