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Subject: Re: [PATCH] jffs2: ensure wbuf_verify is valid before using it.
From:   Hou Tao <houtao1@huawei.com>
To:     <linux-mtd@lists.infradead.org>, <dwmw2@infradead.org>
CC:     <richard.weinberger@gmail.com>, <boris.brezillon@bootlin.com>,
        <linux-kernel@vger.kernel.org>, <stable@vger.kernel.org>
References: <20181020120849.65708-1-houtao1@huawei.com>
 <df5b520c-bc32-e550-4c58-2c79d5e09893@huawei.com>
Message-ID: <0c465568-8459-5164-bba9-8a1651b97bb6@huawei.com>
Date:   Sat, 15 Dec 2018 21:24:06 +0800
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ping ?

On 2018/12/9 14:35, Hou Tao wrote:
> ping ?
> 
> On 2018/10/20 20:08, Hou Tao wrote:
>> Now MTD emulated by UBI volumn doesn't allocate wbuf_verify in
>> jffs2_ubivol_setup(), because UBI can do the verifcation itself,
>> so when CONFIG_JFFS2_FS_WBUF_VERIFY is enabled and a MTD device
>> emulated by UBI volumn is used, a Oops will occur as show in the
>> following trace:
>>
>>     general protection fault: 0000 [#1] SMP KASAN PTI
>>     CPU: 6 PID: 404 Comm: kworker/6:1 Not tainted 4.19.0-rc8
>>     Workqueue: events_long delayed_wbuf_sync
>>     RIP: 0010:ubi_io_read+0x156/0x650
>>     Call Trace:
>>      ubi_eba_read_leb+0x57d/0xba0
>>      ubi_leb_read+0xe5/0x1b0
>>      gluebi_read+0x10c/0x1a0
>>      mtd_read+0x112/0x340
>>      jffs2_verify_write+0xef/0x440
>>      __jffs2_flush_wbuf+0x3fa/0x3540
>>      jffs2_flush_wbuf_gc+0x1b1/0x2e0
>>      process_one_work+0x58b/0x11e0
>>      worker_thread+0x8f/0xfe0
>>      kthread+0x2ae/0x3a0
>>      ret_from_fork+0x35/0x40
>>
>> Fix the problem by checking the validity of wbuf_verify before
>> using it in jffs2_verify_write().
>>
>> Cc: stable@vger.kernel.org
>> Fixes: 0029da3bf430 ("JFFS2: add UBI support")
>> Signed-off-by: Hou Tao <houtao1@huawei.com>
>> ---
>>  fs/jffs2/wbuf.c | 7 +++++++
>>  1 file changed, 7 insertions(+)
>>
>> diff --git a/fs/jffs2/wbuf.c b/fs/jffs2/wbuf.c
>> index c6821a509481..3de45f4559d1 100644
>> --- a/fs/jffs2/wbuf.c
>> +++ b/fs/jffs2/wbuf.c
>> @@ -234,6 +234,13 @@ static int jffs2_verify_write(struct jffs2_sb_info *c, unsigned char *buf,
>>  	size_t retlen;
>>  	char *eccstr;
>>  
>> +	/*
>> +	 * MTD emulated by UBI volume doesn't allocate wbuf_verify,
>> +	 * because it can do the verification itself.
>> +	 */
>> +	if (!c->wbuf_verify)
>> +		return 0;
>> +
>>  	ret = mtd_read(c->mtd, ofs, c->wbuf_pagesize, &retlen, c->wbuf_verify);
>>  	if (ret && ret != -EUCLEAN && ret != -EBADMSG) {
>>  		pr_warn("%s(): Read back of page at %08x failed: %d\n",
>>
> 
> 
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