From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794349956; b=u2FyDEeSdwUnVPeP3iJ+ZUX7LCD4iXIhh434N+DSVgSMThtVziWD4p89vQpW9UmFF9G8 cUlNu9D8jutfyQVNXsL1IRPyTl67YFyr/w/JwWKQfjcYmN/7mmKs9YAsi/e6iJmw9lfbT JhFrG/piTu5Wv8etxJCPAl/IiwKrmh29KomrAlOBVX8szcDCdq39hgRRWCY7eqrjTOuEl 83J2NvPYmIPi7G3WG6b9bJOl7X+xSzg40+4R8yXuYskOAVZ36oAULef5snWfLX3SeeQUS sBRf5prF0dMVMX9hKGU/kk9C/DWU7pRCkgp0xUzGxWJLzRVMZoh8yGhphEfxRSmraFQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794349956; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=DN9YyLAHFEeZtkSI1xaRdnRxY+jclMNX6wFckRPNz1E=; b=VIkIBh/wLOUpM7A1YzKUe0VYQ31ck7TNl1dVLDMh77iN9Z4wnWhq3SQoxoKmJfCcZqaV Yai0a07Tp37oV4LZMkWaDV2HMsn/GmSbtfNqpyLNa0E39SC4CIft9MJGqSPL94Oxe+Qpw xfYB4LNS5CQ9v0mTCs/96al5crnEX3uL/eD/DgB/fP/iEpq+MVXDqAeT2CSqIOgp73C2o sOCXmRUloqpi3+9umHkI5xoCAmFvhFSb8UWBr8sWSCnEVuYm672AIxMKRWo1qR7msuK6S ZEXiTQ/jxD5lgR1TJsR6WzWXyZu3QyENPlw6dN51dJnUm79UIuIhv6ypUIyf6ukdreA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=HRmM+5e7; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 36DBE606A31C for ; Tue, 10 Nov 2026 22:32:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=HRmM+5e7 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 675021F008A2; Tue, 10 Nov 2026 22:32:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794349956; bh=DN9YyLAHFEeZtkSI1xaRdnRxY+jclMNX6wFckRPNz1E=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=HRmM+5e7iu0qc0R32W1RqS40fQX8WR29Az8iaKXYZts4s8zK5mvzBkytZ+iXK4Aol thq3miogvlVQGitUHi3VUFs2XdV7RD+PlSHnUeiLsKr9Yt0SQeZnIssQd4Os42eIDy Q+k3zF2YbIOPET/BoB4ib18csrgvfE5i38Wv7WzmqAuk5j1/IBQPVnjmG8OML1yHL+ 6EFV/dUslcOSy/2czOFxMkCQuas3M0nOGT9KWLnsQT6S2c96PrCuOOD/UrDs8SpxrX fNX1AgugkHerc1OcmKCq1iFMkvgvaAKZfBf74Wnta5tDXxkMZkGIWRfPqaxanYhXHG nlPyFRZ0q5LBg== From: Sasha Levin To: stable@vger.kernel.org Cc: Kaixuan Li , stable@kernel.org, Chao Yu , Jaegeuk Kim , Sasha Levin Subject: [PATCH 5.10.y] f2fs: bound the SIT/NAT bitmaps by the checkpoint pack Date: Tue, 10 Nov 2026 17:32:34 -0500 Message-ID: <20261110223036.4040558-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107062405-failed-5.10-080833a32fd5@kernel.org> References: <20261107062405-failed-5.10-080833a32fd5@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Kaixuan Li [ Upstream commit 080833a32fd5dc10b3acf2fa9af9b3213e6cb617 ] sit_ver_bitmap_bytesize and nat_ver_bitmap_bytesize are used as memcpy lengths into and out of sbi->ckpt, which is sized from cp_payload alone, and nothing compares either length against that allocation. sanity_check_ckpt() has checked these two fields since c77ec61ca0a4, which added them after a crafted image overran build_sit_info(). That check ties each length to a segment count; it never compares either against the allocation, which is the half this adds. Mounting over-reads in build_sit_info() and build_node_manager(), and the first checkpoint writes the same lengths back through the same pointers, so the over-read's contents reach the on-disk checkpoint. An unmount is enough; the filesystem does not have to be used. Bound both ends the way __bitmap_ptr() lays them out. The three branches differ, so a single sum of the two lengths would still admit a small overflow when cp_payload is non-zero. Fixes: 39a53e0ce0df ("f2fs: add superblock and major in-memory structure") Cc: stable@kernel.org Signed-off-by: Kaixuan Li Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim [ sashal: replaced both F2FS_BLKSIZE(sbi) uses with the existing F2FS_BLKSIZE constant ] Signed-off-by: Sasha Levin --- fs/f2fs/super.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index ad0f29f579463..56ee5a097c864 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -3030,6 +3030,7 @@ int f2fs_sanity_check_ckpt(struct f2fs_sb_info *sbi) block_t avail_node_count, valid_node_count; unsigned int nat_blocks, nat_bits_bytes, nat_bits_blocks; unsigned int sit_blk_cnt; + unsigned long long ckpt_size, sit_end, nat_end; int i, j; total = le32_to_cpu(raw_super->segment_count); @@ -3148,6 +3149,29 @@ int f2fs_sanity_check_ckpt(struct f2fs_sb_info *sbi) return 1; } + /* + * Nothing above ties the bitmap lengths to sbi->ckpt, which is + * (1 + cp_payload) blocks. Bound both ends the way __bitmap_ptr() + * lays them out. + */ + ckpt_size = (unsigned long long)(cp_payload + 1) * F2FS_BLKSIZE; + if (__is_set_ckpt_flags(ckpt, CP_LARGE_NAT_BITMAP_FLAG)) { + nat_end = CP_MIN_CHKSUM_OFFSET + sizeof(__le32) + nat_bitmap_size; + sit_end = nat_end + sit_bitmap_size; + } else if (cp_payload > 0) { + nat_end = CP_MIN_CHKSUM_OFFSET + nat_bitmap_size; + sit_end = F2FS_BLKSIZE + sit_bitmap_size; + } else { + sit_end = CP_MIN_CHKSUM_OFFSET + sit_bitmap_size; + nat_end = sit_end + nat_bitmap_size; + } + + if (sit_end > ckpt_size || nat_end > ckpt_size) { + f2fs_err(sbi, "Bitmaps do not fit the checkpoint pack: sit ends at %llu, nat at %llu, pack is %llu bytes", + sit_end, nat_end, ckpt_size); + return 1; + } + if (__is_set_ckpt_flags(ckpt, CP_LARGE_NAT_BITMAP_FLAG) && le32_to_cpu(ckpt->checksum_offset) != CP_MIN_CHKSUM_OFFSET) { f2fs_warn(sbi, "using deprecated layout of large_nat_bitmap, " -- 2.53.0