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From: Sascha Hauer <s.hauer@pengutronix.de>
To: Ahmad Fatoum <a.fatoum@pengutronix.de>
Cc: Barebox List <barebox@lists.infradead.org>
Subject: Re: [PATCH 4/4] fs: free unused dentries
Date: Tue, 15 Sep 2020 15:12:19 +0200	[thread overview]
Message-ID: <20200915131219.GP4498@pengutronix.de> (raw)
In-Reply-To: <5e8911d3-2fe2-f2c7-09da-c971d97e8ff3@pengutronix.de>

On Tue, Sep 15, 2020 at 10:01:23AM +0200, Ahmad Fatoum wrote:
> 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.

Hm, still can't reproduce, neither with
91a23b64445b8861acbfd96fcc03082b343b0211 nor with current next.

Sascha


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  reply	other threads:[~2020-09-15 13:12 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
2020-09-15 13:12         ` Sascha Hauer [this message]
2020-09-15 13:28           ` Ahmad Fatoum
2020-09-16 10:43             ` Ahmad Fatoum

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