linux-ext4 - Re: [PATCH] ext4: fix potential use after free in __ext4_journal

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <D351F62D-C7F5-4B8F-8D7C-246DC6BB52CC@dilger.ca>
Date:	Mon, 5 Oct 2015 13:20:52 -0600
From:	Andreas Dilger <adilger@...ger.ca>
To:	Lukáš Czerner <lczerner@...hat.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH] ext4: fix potential use after free in __ext4_journal_stop


> On Oct 5, 2015, at 8:18 AM, Lukáš Czerner <lczerner@...hat.com> wrote:
> 
> On Wed, 2 Sep 2015, Lukas Czerner wrote:
> 
>> Date: Wed,  2 Sep 2015 16:45:54 +0200
>> From: Lukas Czerner <lczerner@...hat.com>
>> To: linux-ext4@...r.kernel.org
>> Cc: Lukas Czerner <lczerner@...hat.com>
>> Subject: [PATCH] ext4: fix potential use after free in __ext4_journal_stop
>> 
>> There is a use-after-free possibility in __ext4_journal_stop() in the
>> case that we free the handle in the first jbd2_journal_stop() because
>> we're referencing handle->h_err afterwards. This was introduced in
>> 9705acd63b125dee8b15c705216d7186daea4625 and it is wrong. Fix it by
>> storing the handle->h_err value beforehand and avoid referencing
>> potentially freed handle.
> 
> ping
>> 
>> Signed-off-by: Lukas Czerner <lczerner@...hat.com>

Reviewed-by: Andreas Dilger <adilger@...ger.ca>

>> ---
>> fs/ext4/ext4_jbd2.c | 6 +++---
>> 1 file changed, 3 insertions(+), 3 deletions(-)
>> 
>> diff --git a/fs/ext4/ext4_jbd2.c b/fs/ext4/ext4_jbd2.c
>> index d418431..e770c1ee 100644
>> --- a/fs/ext4/ext4_jbd2.c
>> +++ b/fs/ext4/ext4_jbd2.c
>> @@ -88,13 +88,13 @@ int __ext4_journal_stop(const char *where, unsigned int line, handle_t *handle)
>> 		return 0;
>> 	}
>> 
>> +	err = handle->h_err;
>> 	if (!handle->h_transaction) {
>> -		err = jbd2_journal_stop(handle);
>> -		return handle->h_err ? handle->h_err : err;
>> +		rc = jbd2_journal_stop(handle);
>> +		return err ? err : rc;
>> 	}
>> 
>> 	sb = handle->h_transaction->t_journal->j_private;
>> -	err = handle->h_err;
>> 	rc = jbd2_journal_stop(handle);
>> 
>> 	if (!err)
>> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> the body of a message to majordomo@...r.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html


Cheers, Andreas






Download attachment "signature.asc" of type "application/pgp-signature" (834 bytes)