From nobody Mon Dec 1 21:30:55 2025 Received: from mail-pl1-f178.google.com (mail-pl1-f178.google.com [209.85.214.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A40231FDA for ; Mon, 1 Dec 2025 09:25:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.178 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764581104; cv=none; b=rOcBIQ79sXVcUNwIZ81NmfZPE0z8+Jx3mhnEWfL3H3+lSew71kuojx+OSLTM+gj+EqA6E8q7HTokgrRE8uvtOXbDgoVacGxbjPUzsU73CPXoQhgAwxJTqLw7j1PtDdPmO73/31QBC0pPMYrHKJ0TzFiKr8TwoS24iSOWjBM0UOY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764581104; c=relaxed/simple; bh=d9GBTfOrFJjQNQxndzxCPwaJdkYd9QaUiqFnCs8pM8Y=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=ir1H2R8/M+v68rMlNc4rw58Zkb1nKhzITCJAPdsFSrznVBGCrsw3ZJ1LRzLnEdyi2Z+YsqrCi2XrgmMLhhdb2fFl8G3yCKZ0uihgpgYmeTj9BtnW0jKVPHIrx2pKLktRSsj7N0J7Mey7Hs2DcfjTiW+LM5BOQMvKTdHHnovdsSg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=Cp5KPLRL; arc=none smtp.client-ip=209.85.214.178 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Cp5KPLRL" Received: by mail-pl1-f178.google.com with SMTP id d9443c01a7336-298039e00c2so56504635ad.3 for ; Mon, 01 Dec 2025 01:25:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1764581101; x=1765185901; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=qERR8P+/o4ObMaf4NL7eL/6PohQaFQTnCKkZHGpKlnM=; b=Cp5KPLRL66V+BLxH8ke8ZrenzCDZZGSRDrtvsDhxtQK8NE2++nJgwRCZIbSO8H6nJG EE5lzP7azUsPNI8S95h6lv3yVje5m2tIA9d+HvwAFBswi6hbL6ko9lJUt7nL+7Da9GLn tdB3nITbOHH1GAP+BLrUJ86QiL2DR8JdATkG5ABvKXxxp3m+S7BMNXKA5bkVp5A7akAZ ghGmRFxjh597lG1j9221drPe3dA0GRl1/RmvDxKqyHtb9DtpqfyjhoKzM/bePl+y+Oe7 HebRo/UXS7W8Dd5FRDxRDp3+eBiiGSAicgruCY6CglKsV+07LGRB9YxTlBtA/swSHeD2 iT5w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1764581101; x=1765185901; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=qERR8P+/o4ObMaf4NL7eL/6PohQaFQTnCKkZHGpKlnM=; b=KxpuDT50tgI0qkXyQor9pn+ifRNs7HsK4fJW+776pQTiX3ofQSeaVycruJHLH0kuLo 2qj0cjC8q+84H8C4LYEBDS6+Sq5NBY4VBOi2iyZ95qGFDHXAsnz3GpxNW//n0P8TOf+f 4FpT5X2kVJOHGR3Hqh+Mp8zP6RlGDsxWXeOPmnCFC+hvQoU5dpBW/SuoJPhliZ44zJQz k65jgwZmAaUKZPGVy45YvePAC9JezNGW5cQE8c7IRATMedb4vy320HxMHMVGuGR7SxA7 PHjYSTckD1X6mIOiRfr34DWKasozt+EKbK/3/N8roxasbpMSNfUdbQWNFgx58w2yK6bc nAyQ== X-Forwarded-Encrypted: i=1; AJvYcCVZkXAegYAcc7YFRLu0XO0eVPkKd9/1tG3eMfIjOGL1zQl2Z2t3EHSDWH5Hu+w6VVzuSNXA86VPQfO6LCg=@vger.kernel.org X-Gm-Message-State: AOJu0Ywy13zQe2Uum/zD9nLiNYkmGRYYV34truNJeOvvBii3Emz58ik8 P/2uJmkpPBuHXeANU1RYztyDiGZVYhvjlgBS+ADnQ5qKrnhvQrAr7oYX X-Gm-Gg: ASbGncuP63rpU2NVhYTXsVkZxAobNzQIebm0oNxu6fgK44RoUiG6Br3cGLGpyQVi6gx FbEI1V00JTELWif5GaQfoFaNqlJoRliKkvsSoNAa3l6nHAiPU8h7mPgIsCuRE9Sg9ol+nil0d4y JdX+x5aWVQTgxnVJslShHhYv2VPy+sJm9rZNvqc2OR4U42JcrS1YCdqmzbQMnKTijF2MUwZU7uj yzxlCl8mmO5nyRGVTBNapZXS7ym5b21fXx130xDj/GkmmK3A4bgeCiCpYS+Rss1GgNgNgczSmmF /FUGbvDbuGwNZPaM52o6fPCD4OjISb5GRsVcN5s7x87UG4AQQx8z5aVPOPBxubyW/6Zr//fCGm8 4l5gBoOd5b5VQhfiV2PyWZ8jVcYkpYXNMOQ07uYZz3V5fjzELbyREUUVysWVzv3wveDD29lO3nm DJvVD82ncCly18hSXPQIUoZ8hDugQ= X-Google-Smtp-Source: AGHT+IFXnf0d/pxuEm+gHoXJiVlLVuf56GuwzRCPB2DmvUZXgNgKDE4fu8biWpWXfSyNlaPjS17cGw== X-Received: by 2002:a17:903:2c10:b0:298:42ba:c437 with SMTP id d9443c01a7336-29b6bf75998mr389621755ad.50.1764581100937; Mon, 01 Dec 2025 01:25:00 -0800 (PST) Received: from localhost.localdomain ([114.79.136.226]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-29bce441e59sm118620605ad.33.2025.12.01.01.24.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 01 Dec 2025 01:25:00 -0800 (PST) From: Prithvi Tambewagh To: mark@fasheh.com, jlbec@evilplan.org, joseph.qi@linux.alibaba.com Cc: ocfs2-devel@lists.linux.dev, linux-kernel@vger.kernel.org, linux-kernel-mentees@lists.linux.dev, skhan@linuxfoundation.org, david.hunter.linux@gmail.com, khalid@kernel.org, Prithvi Tambewagh , syzbot+96d38c6e1655c1420a72@syzkaller.appspotmail.com, stable@vger.kernel.org Subject: [PATCH v2] ocfs2: fix kernel BUG in ocfs2_find_victim_chain Date: Mon, 1 Dec 2025 14:54:49 +0530 Message-Id: <20251201092450.84991-1-activprithvi@gmail.com> X-Mailer: git-send-email 2.34.1 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 a kernel BUG in ocfs2_find_victim_chain() because the `cl_next_free_rec` field of the allocation chain list is 0, triggring the BUG_ON(!cl->cl_next_free_rec) condition and panicking the kernel. To fix this, `cl_next_free_rec` is checked inside the caller of ocfs2_find_victim_chain() i.e. ocfs2_claim_suballoc_bits() and if it is equal to 0, ocfs2_error() is called, to log the corruption and force the filesystem into read-only mode, to prevent further damage. Reported-by: syzbot+96d38c6e1655c1420a72@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3D96d38c6e1655c1420a72 Tested-by: syzbot+96d38c6e1655c1420a72@syzkaller.appspotmail.com Cc: stable@vger.kernel.org Signed-off-by: Prithvi Tambewagh --- v1->v2: - Remove extra line before the if statement in patch - Add upper limit check for cl->cl_next_free_rec in the if condition fs/ocfs2/suballoc.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c index 6ac4dcd54588..1257c39c2c11 100644 --- a/fs/ocfs2/suballoc.c +++ b/fs/ocfs2/suballoc.c @@ -1992,6 +1992,13 @@ static int ocfs2_claim_suballoc_bits(struct ocfs2_al= loc_context *ac, } =20 cl =3D (struct ocfs2_chain_list *) &fe->id2.i_chain; + if (!le16_to_cpu(cl->cl_next_free_rec) || + le16_to_cpu(cl->cl_next_free_rec) > le16_to_cpu(cl->cl_count)) { + status =3D ocfs2_error(ac->ac_inode->i_sb, + "Chain allocator dinode %llu has 0 chains\n", + (unsigned long long)le64_to_cpu(fe->i_blkno)); + goto bail; + } =20 victim =3D ocfs2_find_victim_chain(cl); ac->ac_chain =3D victim; base-commit: 939f15e640f193616691d3bcde0089760e75b0d3 --=20 2.34.1