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([2405:201:682f:389d:8847:f08b:572c:9775]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7e7f42a43basm7660212b3a.2.2025.12.08.00.44.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Dec 2025 00:44:14 -0800 (PST) From: Deepanshu Kartikey To: mark@fasheh.com, jlbec@evilplan.org, joseph.qi@linux.alibaba.com Cc: ocfs2-devel@lists.linux.dev, linux-kernel@vger.kernel.org, Deepanshu Kartikey , syzbot+6d832e79d3efe1c46743@syzkaller.appspotmail.com Subject: [PATCH] ocfs2: validate i_refcount_loc when refcount flag is set Date: Mon, 8 Dec 2025 14:14:07 +0530 Message-ID: <20251208084407.3021466-1-kartikey406@gmail.com> X-Mailer: git-send-email 2.43.0 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" Add validation in ocfs2_validate_inode_block() to check that if an inode has OCFS2_HAS_REFCOUNT_FL set, it must also have a valid i_refcount_loc. A corrupted filesystem image can have this inconsistent state, which later triggers a BUG_ON in ocfs2_remove_refcount_tree() when the inode is being wiped during unlink. Catch this corruption early during inode validation to fail gracefully instead of crashing the kernel. Reported-by: syzbot+6d832e79d3efe1c46743@syzkaller.appspotmail.com Tested-by: syzbot+6d832e79d3efe1c46743@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3D6d832e79d3efe1c46743 Signed-off-by: Deepanshu Kartikey --- fs/ocfs2/inode.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c index 78f81950c9ee..dd56407fc056 100644 --- a/fs/ocfs2/inode.c +++ b/fs/ocfs2/inode.c @@ -1484,6 +1484,13 @@ int ocfs2_validate_inode_block(struct super_block *s= b, goto bail; } =20 + if ((di->i_dyn_features & cpu_to_le16(OCFS2_HAS_REFCOUNT_FL)) && + !di->i_refcount_loc) { + rc =3D ocfs2_error(sb, "Invalid dinode #%llu: refcount flag set but i_re= fcount_loc is zero\n", + (unsigned long long)bh->b_blocknr); + goto bail; + } + rc =3D 0; =20 bail: --=20 2.43.0