From: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
To: Randy Dunlap <rdunlap@infradead.org>,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
Andrew Morton <akpm@linux-foundation.org>,
Namjae Jeon <linkinjeon@kernel.org>,
Shigeru Yoshida <syoshida@redhat.com>
Cc: syzbot <syzbot+1631f09646bc214d2e76@syzkaller.appspotmail.com>,
<syzkaller-bugs@googlegroups.com>, <ntfs3@lists.linux.dev>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] fs/ntfs3: fix negative shift size in true_sectors_per_clst()
Date: Fri, 23 Sep 2022 14:58:21 +0300 [thread overview]
Message-ID: <1bf6d8ea-9e81-f65a-d7dc-6e94fa12da7b@paragon-software.com> (raw)
In-Reply-To: <e0173c17-3837-a619-4bcc-7a0ba4843cc4@infradead.org>
On 9/23/22 03:38, Randy Dunlap wrote:
> Hi,
>
> On 9/20/22 08:59, Tetsuo Handa wrote:
>> syzbot is reporting shift-out-of-bounds in true_sectors_per_clst() [1], for
>> commit a3b774342fa752a5 ("fs/ntfs3: validate BOOT sectors_per_clusters")
>> did not address that (0 - boot->sectors_per_clusters) < 0 because "u8" was
>> chosen for type of boot->sectors_per_clusters because 0x80 needs to be
>> positive in order to support 64K clusters. Use "s8" cast in order to make
>> sure that (0 - (s8) boot->sectors_per_clusters) > 0.
>>
>> Link: https://syzkaller.appspot.com/bug?extid=1631f09646bc214d2e76 [1]
>> Reported-by: syzbot <syzbot+1631f09646bc214d2e76@syzkaller.appspotmail.com>
>> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
>> Tested-by: syzbot <syzbot+1631f09646bc214d2e76@syzkaller.appspotmail.com>
>> Fixes: a3b774342fa752a5 ("fs/ntfs3: validate BOOT sectors_per_clusters")
>>
>> diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c
>> index 47012c9bf505..c7ffd21fb255 100644
>> --- a/fs/ntfs3/super.c
>> +++ b/fs/ntfs3/super.c
>> @@ -672,7 +672,7 @@ static u32 true_sectors_per_clst(const struct NTFS_BOOT *boot)
>> if (boot->sectors_per_clusters <= 0x80)
>> return boot->sectors_per_clusters;
>> if (boot->sectors_per_clusters >= 0xf4) /* limit shift to 2MB max */
>> - return 1U << (0 - boot->sectors_per_clusters);
>> + return 1U << (0 - (s8) boot->sectors_per_clusters);
>> return -EINVAL;
>> }
>>
>
> I slightly prefer the earlier patch:
>
> https://lore.kernel.org/all/20220823144625.1627736-1-syoshida@redhat.com/
>
> but it appears that the NTFS3 maintainer is MIA again. :(
>
Hello
I've sent patches on 12.09, so I'm not MIA.
I plan to look at patches next week, there are quite a lot of them.
next prev parent reply other threads:[~2022-09-23 12:03 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-21 8:16 [syzbot] UBSAN: shift-out-of-bounds in ntfs_fill_super syzbot
2022-04-21 8:37 ` syzbot
2022-04-21 12:29 ` syzbot
2022-09-20 15:59 ` [PATCH] fs/ntfs3: fix negative shift size in true_sectors_per_clst() Tetsuo Handa
2022-09-23 0:38 ` Randy Dunlap
2022-09-23 0:47 ` Joe Perches
2022-09-23 1:14 ` Randy Dunlap
2022-09-23 9:59 ` Dan Carpenter
2022-09-23 1:25 ` Tetsuo Handa
2022-09-23 11:58 ` Aleksandr Nogikh
2022-09-23 14:35 ` Tetsuo Handa
2022-09-24 11:58 ` Aleksandr Nogikh
2022-09-24 12:03 ` Aleksandr Nogikh
2022-09-23 11:58 ` Konstantin Komarov [this message]
2022-09-23 16:07 ` Randy Dunlap
2022-09-30 16:34 ` Konstantin Komarov
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