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From: Chao Yu <chao@kernel.org>
To: Seongjae Jeong <jsjlee1020@gmail.com>, jaegeuk@kernel.org
Cc: chao@kernel.org, daehojeong@google.com,
	linux-f2fs-devel@lists.sourceforge.net,
	linux-kernel@vger.kernel.org,
	syzbot+ae5b8eb92ed40411ce16@syzkaller.appspotmail.com
Subject: Re: [PATCH] f2fs: reject device aliasing without a multi-device configuration
Date: Wed, 30 Sep 2026 16:10:43 +0800	[thread overview]
Message-ID: <989ede44-7d64-48b1-af9b-a0a45f824ab3@kernel.org> (raw)
In-Reply-To: <20260918133922.8163-1-jsjlee1020@gmail.com>

On 9/18/26 21:39, Seongjae Jeong wrote:
> A malformed F2FS image can enable F2FS_FEATURE_DEVICE_ALIAS without
> providing a multi-device configuration. For a regular single-device
> filesystem, f2fs_scan_devices() returns without allocating sbi->devs.
> 
> In this state, f2fs_dev_is_alloc_blocked() passes the device alias
> feature check and dereferences FDEV(0), resulting in a NULL pointer
> dereference during segment allocation.
> 
> Device aliasing requires at least one secondary device. Reject
> superblocks that enable device aliasing without entries for both the
> main and secondary devices in sanity_check_raw_super().
> 
> Fixes: eae3faf210bd ("f2fs: support dynamic reserve/release for device aliasing")
> Reported-by: syzbot+ae5b8eb92ed40411ce16@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=ae5b8eb92ed40411ce16
> Signed-off-by: Seongjae Jeong <jsjlee1020@gmail.com>

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,

  reply	other threads:[~2026-09-30  8:10 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-18 13:39 Seongjae Jeong
2026-09-30  8:10 ` Chao Yu [this message]
2026-09-30 17:20 ` [f2fs-dev] " patchwork-bot+f2fs

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