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=1794346643; b=5RrPLgWVvB3bMKm/dFZ0Uoj46oY5p8r9+31UZPsafgZafIsCZKM475Jpq/kmNvedqv2p 5b3nzP12aMOFevmz+7LPVs8nY1ESEcHd5eUOot/7wCJaqGz321ZZ8EqSXntK9eN1sAK6a nsS7ANo7mBT9SKfuXOlTZh5D9BhXbsAlvGjYGVtqnbumvWA6Mgl67RQWpHJYlNcFewWQe vGTofF4fG/OHpLkk/1/8N6Cz3r0dUk42vy4iYeI0BkBRPjlAMxXPBCq0rZ2MJvvtGtmeX wlZ07hnjejubedgycvac/DkQqoTDvel6hrEQ76XoirWYLUMH9v4YppnsBIxHjNyqIuw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794346643; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=JeAlVsVNVXxg5LJ1Nt9/PQy/ettNVIB2Xs3BGyBTOPw=; b=TiELrHYY321T69gDtHHZQv+brcOsmP08dhuIoPOxodOYr3+EnmEBjuqUkdfxP6HGtFcJ gBNMslcLKfJkSNM4AxU6i6VgNnX/Tkvhsb2NEAcuQsxMcjnA6xkTXmSv0LdyfIDnsBbbX 5sWjWaY7MzH2W35RFi08O7xFZk6dD9ebZVpsNiaXe1EuyedlP2EfnV6ArH+ihj7pVizZK 7Lo0hlJiDME4/Qs7ZFHqgAOsaGxj9KvDyFSjVA29cPhGBuL3RHz09x0SM2/mg3I520k0r w0LB+l4agM6LfJ4IsudUuf8+QmZl5aq9xOftfWWhhyYWA8WT/dI+1vflNxbGzjXvURQ== 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=UyOVwxGl; 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 E027C606A332 for ; Tue, 10 Nov 2026 21:37:22 +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=UyOVwxGl Received: by smtp.kernel.org (Postfix) with ESMTPSA id C29F11F008A1; Tue, 10 Nov 2026 21:37:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794346642; bh=JeAlVsVNVXxg5LJ1Nt9/PQy/ettNVIB2Xs3BGyBTOPw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=UyOVwxGlZAy7rJCCyVKzB67uqZJSK56IZXH7QmtQyNtpBntG8dwZBimKh5n8ABJjn WzIoAm1T6yMvSVGT0l5SoAHAAKQhwFdDD0R1NJUjXAHIzt5bfJOEi8x6FBkJT46ec0 u7X3/QaU32MBu0mlc0WXdfsAZsi1tHI5y8jpuvMeIS/UBNPo4uJRz35A3g18rUEWt5 kotdmOlOMXBEnfCOgTM8QURq1CMG5YKkOmc5bV7vDSIaGGRTVShu7d45lwmB/TaDTG J83dPzvLiQNkS5rtK/NCNHWn5UjWKiAWrzKvfDOpKKIH1aNiPePJUX8+CUUsE2t3Qe +EM9Yg3v6FBUg== From: Sasha Levin To: stable@vger.kernel.org Cc: Kaixuan Li , stable@kernel.org, Chao Yu , Jaegeuk Kim , Sasha Levin Subject: [PATCH 6.12.y] f2fs: bound the SIT/NAT bitmaps by the checkpoint pack Date: Tue, 10 Nov 2026 16:37:19 -0500 Message-ID: <20261110213551.3918808-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107052312-failed-6.12-080833a32fd5@kernel.org> References: <20261107052312-failed-6.12-080833a32fd5@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 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 31724ab224d4a..ec3e20cd6c5eb 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -3773,6 +3773,7 @@ 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); @@ -3904,6 +3905,29 @@ 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