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=1794348136; b=1GLE/m15vh9cOB+xuWW0aDXsE0j7LW5hVGztNkDpb7+WQb8N4BopjoiM2twVINvwt2cw mGIplnN+uuzs/xtpHFHGgZla29i5Ni3talj+ssW4BFU5H0xE/J7HG79xoJBg/2tuXBF31 +noSgbHFesPGUC4RFzHYyfoKTafldCBAmo8oePQPDZ+7Dg44Ukqffuuqt5aSoOHmPm8qW muU38FN/ZyaseZ+h5ISDt1bFurwyRPmL4iDhMCCqDGLZgsBPIuIPnjvvtOy88ocmc9MEB r7vb0Z5FugpkpbpEc8uY/8FLOu8SMAl0+fwV81y0JM+G9h2BPTf9+EiYaCHVPCjo0bA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794348136; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=emq8jmanvB3G0F7LubffLV2bdhN8Gqxf4XaL1jtvBuc=; b=PQJ2h9oOiBn9LD4jC4Y+cQuLFpgDY2rTnzrhSyqElXJ3e8vY3lfSP9KBzIQEtiEn8RIX WYo3pyxKzXTAiKFZ0Oej33SLJkM2viSyQdvOCabVxUnx0rU73+aIXXiLbSpv69t1x61m2 Bobszh4VzuRn+BTNkYffyQOg0FwxVD5k+fLIEK+6jfDVdOzbessjo9qj72p+W6t1PygEd yKews+DqNsrDuvmZAsMgTcfKsaCaKyPBsUMTibEfOslj0M8gkIxDZrzR/wyUONfsf07Rb O3b8ijWj3nftKl+KvMMIvWpazCb9Ls5mX/8iqUuVPKMS9va4RlmLNVc0kPKbIgL9kEw== 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=fcUsiqWW; 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 241A7606A31C for ; Tue, 10 Nov 2026 22:02:15 +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=fcUsiqWW Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0AF721F0089F; Tue, 10 Nov 2026 22:02:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794348135; bh=emq8jmanvB3G0F7LubffLV2bdhN8Gqxf4XaL1jtvBuc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=fcUsiqWWTheVufgV1WLGI5BUHWbeD4f7Y71Up+/rR/Suj1cvjdLijkMKQHQdRs1pE zIKKplH0Xunmdn6eJ9UFcy/IPn7B4rpcDoL+Yg2YTU1CNFRAJx9BOp9mxrk2B0hEOi Re2IsI+fchvWpJygX0ZYzewiLvrkckp3a1yQNrmeloOFkvij5UyKocc05uHdBSwEWy 4Rx95xqzhKOMDYBm8hfTLDBhxb8Ol3bvPv5H+vie+4g2QJyRNu0EputQuZpKtn488m D8H9+8N4DrpBPhioDUTXSakaTBvYLeP1sAXQSLmmLO3J4/dIB36AJZ/oyNF2SX2nAQ vhjntE6PozkRA== From: Sasha Levin To: stable@vger.kernel.org Cc: Kaixuan Li , stable@kernel.org, Chao Yu , Jaegeuk Kim , Sasha Levin Subject: [PATCH 6.1.y] f2fs: bound the SIT/NAT bitmaps by the checkpoint pack Date: Tue, 10 Nov 2026 17:02:13 -0500 Message-ID: <20261110215940.3991417-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107055006-failed-6.1-080833a32fd5@kernel.org> References: <20261107055006-failed-6.1-080833a32fd5@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 F2FS_BLKSIZE(sbi) with the constant F2FS_BLKSIZE in two expressions. ] 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 1b6d28116a04c..89d1de05cb31c 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -3553,6 +3553,7 @@ 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); @@ -3684,6 +3685,29 @@ 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