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[118.19.49.33]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-20d1805cc09sm16768935ad.275.2024.10.15.14.33.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Oct 2024 14:33:05 -0700 (PDT) From: Ryusuke Konishi To: Andrew Morton Cc: linux-nilfs@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot , syzkaller-bugs@googlegroups.com, linux-fsdevel@vger.kernel.org Subject: [PATCH] nilfs2: fix kernel bug due to missing clearing of buffer delay flag Date: Wed, 16 Oct 2024 06:32:07 +0900 Message-ID: <20241015213300.7114-1-konishi.ryusuke@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <670cb3f6.050a0220.3e960.0052.GAE@google.com> References: <670cb3f6.050a0220.3e960.0052.GAE@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Syzbot reported that after nilfs2 reads a corrupted file system image and degrades to read-only, the BUG_ON check for the buffer delay flag in submit_bh_wbc() may fail, causing a kernel bug. This is because the buffer delay flag is not cleared when clearing the buffer state flags to discard a page/folio or a buffer head. So, fix this. This became necessary when the use of nilfs2's own page clear routine was expanded. This state inconsistency does not occur if the buffer is written normally by log writing. Signed-off-by: Ryusuke Konishi Reported-by: syzbot+985ada84bf055a575c07@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3D985ada84bf055a575c07 Fixes: 8c26c4e2694a ("nilfs2: fix issue with flush kernel thread after remo= unt in RO mode because of driver's internal error or metadata corruption") Cc: stable@vger.kernel.org --- Andrew, please apply this as a bug fix. This fixes a kernel bug recently reported by Syzbot. Thanks, Ryusuke Konishi fs/nilfs2/page.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/nilfs2/page.c b/fs/nilfs2/page.c index 9c0b7cddeaae..5436eb0424bd 100644 --- a/fs/nilfs2/page.c +++ b/fs/nilfs2/page.c @@ -77,7 +77,8 @@ void nilfs_forget_buffer(struct buffer_head *bh) const unsigned long clear_bits =3D (BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) | BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) | - BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected)); + BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected) | + BIT(BH_Delay)); =20 lock_buffer(bh); set_mask_bits(&bh->b_state, clear_bits, 0); @@ -406,7 +407,8 @@ void nilfs_clear_folio_dirty(struct folio *folio) const unsigned long clear_bits =3D (BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) | BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) | - BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected)); + BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected) | + BIT(BH_Delay)); =20 bh =3D head; do { --=20 2.43.0