linux-ext4 - Re: [PATCH] ext4: do not use extent after put

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Message-ID: <93d5b1bf-0cf9-a483-ff5d-40a6a9c4b92b@linux.ibm.com>
Date:   Thu, 29 Oct 2020 21:38:34 +0530
From:   Ritesh Harjani <riteshh@...ux.ibm.com>
To:     yangerkun <yangerkun@...wei.com>, adilger@...ger.ca
Cc:     tytso@....edu, jack@...e.com, linux-ext4@...r.kernel.org
Subject: Re: [PATCH] ext4: do not use extent after put_bh



On 10/28/20 11:26 AM, yangerkun wrote:
> ext4_ext_search_right will read more extent block and call put_bh after
> we get the information we need. However ret_ex will break this and may
> cause use-after-free once pagecache has been freed. Fix it by dup the
> extent we need.


It would be good if we have a test case to reproduce it. Do you?
Ideally it should go in fstests, if you have some way to forcefully
reproduce it/simulate it. Let me know, if needed, I can as well help to
get those into fstests.

-ritesh