From: Ahmad Fatoum <a.fatoum@pengutronix.de>
To: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Barebox List <barebox@lists.infradead.org>
Subject: Re: [PATCH 4/4] fs: free unused dentries
Date: Tue, 15 Sep 2020 10:01:23 +0200 [thread overview]
Message-ID: <5e8911d3-2fe2-f2c7-09da-c971d97e8ff3@pengutronix.de> (raw)
In-Reply-To: <20200915071215.GZ4498@pengutronix.de>
Hello Sascha,
On 9/15/20 9:12 AM, Sascha Hauer wrote:
> On Tue, Sep 15, 2020 at 07:25:15AM +0200, Ahmad Fatoum wrote:
>> Hello Sascha,
>>
>> On 9/14/20 3:06 PM, Sascha Hauer wrote:
>>> So far we only ever freed dentries when the filesystem they are on is
>>> unmounted. With this patch we actually trust reference counting and free
>>> the dentries once the reference count hits zero.
>>
>> Unless I revert this patch, I run into a crash doing:
>>
>> dd if=/dev/zero of=barebox.env count=1
>> ./barebox --image=barebox.env
>> barebox@barebox sandbox:/ saveenv
>> saving environment
>
> "saveenv" answers with: "saveenv: No such file or directory". Did you
> mean to do a "saveenv /dev/fd0"?
>
>> barebox@barebox sandbox:/ reset
>> =================================================================
>> ==894761==ERROR: AddressSanitizer: heap-use-after-free on address 0x60e000005d70 at pc 0x5617cfde210a bp 0x7ffff89957d0 sp 0x7ffff89957c8
>
> I can't reproduce this here unfortunately.
Sorry, should've been ./barebox --env=barebox.env
I can reproduce it with upstream/next (91a23b64445b8861acbfd96fcc03082b343b0211)
and sandbox_defconfig (+CONFIG_RESET). saveenv; reset results in a segmentation fault.
CONFIG_KASAN=y
CONFIG_MALLOC_LIBC=y
gives the better debugging output.
Cheers,
Ahmad
>
> Sascha
>
>
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next prev parent reply other threads:[~2020-09-15 8:01 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-14 13:06 [PATCH 1/4] fs: don't free device in remove callback Sascha Hauer
2020-09-14 13:06 ` [PATCH 2/4] fs: Drop unnecessary dput() Sascha Hauer
2020-09-14 13:06 ` [PATCH 3/4] fs: Fix use after free Sascha Hauer
2020-09-14 13:06 ` [PATCH 4/4] fs: free unused dentries Sascha Hauer
2020-09-15 5:25 ` Ahmad Fatoum
2020-09-15 7:12 ` Sascha Hauer
2020-09-15 8:01 ` Ahmad Fatoum [this message]
2020-09-15 13:12 ` Sascha Hauer
2020-09-15 13:28 ` Ahmad Fatoum
2020-09-16 10:43 ` Ahmad Fatoum
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