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=1794345230; b=wigXI4YyzThAAingnZvaEFBCFwB0alJI/gN/2mFqHtbrfqKewO4tQKx8PselYwAHeOGL pbjtoZBkJVEj15p05pG74aQ1LKamZ8y1n3U/vWFlKuJJq5sdjSGwEnjGawfiYtfD0tgO9 lH32IicWcYtsi0523tpqJQTeZ13PZpvPLSN1TlHXLYKk3zlouMvTMtACPEaOUzaZh8ycI FlDHhODRxcbuZNbhsF/ieTIFxd/mMAMf1l5crSTmhqI4Y7cOIAAOXEcugDh1jnnmLI7VP IpMLmiXhsXyxZ6EHHpi54PyFHKVwqckzY/dikA/ur06Jh1AnnMuMTngrOC7TAp0deZg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794345230; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=34mxTeZ9eMr8HUFuI5tyYPHaOJJYJMUYfEX+tnuiv1Q=; b=huzsJ4r9/PKuqZ6RLQY3TL9g12qOUY+xLT5EuMr1tuB90P2gkLgLH+5Z4quBjvXleI6d hTRCxR/T6jGf4IXJmqzltm2GbMx1HhSateRH23qEQB++IOHnG4qXsuKg3Pr8bXNF/Pu/3 wP95qvWE/hj/0jj8q8tlbwWgd7V5lw9fop3QBf98CDa884Joyl7oSrV7vGsIu58i3v4x8 djJ/ObuF0zf+HvJaQd8GBU8gljeFQHxOouyr3fWb6h8iispat0aBB09LcwmPgpoE6Ex1A rXQEF2RFPR8aF1JF5qFf/0dKyGOshdrBdA3qwE7Fx6Qu8zd6De1+5mXrHivjeSulxRw== 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=iWIwdJyT; 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 736AB606A327 for ; Tue, 10 Nov 2026 21:13:50 +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=iWIwdJyT Received: by smtp.kernel.org (Postfix) with ESMTPSA id A8E7C1F0089F; Tue, 10 Nov 2026 21:13:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794345230; bh=34mxTeZ9eMr8HUFuI5tyYPHaOJJYJMUYfEX+tnuiv1Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=iWIwdJyThkuSG0TvZbG+v9TsBqGKGP+1wJmsiQfzaS4iGi1am9egoMOipD4lb3poi wbb459K6X0WsZaBi6DRg4KpdQ/m22pyCrePpbD9cdGVEBeQrXEmFCYojlH7Fp+QZUu o6Lbje7/PkCOpRsVkP91R8h/tKxQ4BnLSIbF9J7Kqjft6jtbiptUpHlG9a86GZ810X Mu8LlF/FF8VtVCGftB+ZWDfX8AW6RwwBjTO0CVj9evgwtwHx0+L7QNZG1/Tp9PwUMu HOuDoHo6mZBRiith7gmF7Gh2abR8zPnedCKIdEdIRG2i91aDUw5ASscKFl83xln6oS xAYohXMoEWneA== From: Sasha Levin To: stable@vger.kernel.org Cc: Kaixuan Li , stable@kernel.org, Chao Yu , Jaegeuk Kim , Sasha Levin Subject: [PATCH 6.18.y] f2fs: bound the SIT/NAT bitmaps by the checkpoint pack Date: Tue, 10 Nov 2026 16:13:48 -0500 Message-ID: <20261110211325.3872544-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107051158-failed-6.18-080833a32fd5@kernel.org> References: <20261107051158-failed-6.18-080833a32fd5@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 the two F2FS_BLKSIZE(sbi) calls with the 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 69d36e1a301bf..93e6575706add 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -4128,6 +4128,7 @@ 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); @@ -4259,6 +4260,29 @@ 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