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[34.83.123.78]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3a023cf10bbsm2034432a91.3.2026.09.19.15.26.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 19 Sep 2026 15:26:06 -0700 (PDT) From: Hui Peng To: slava@dubeyko.com, glaubitz@physik.fu-berlin.de, frank.li@vivo.com, brauner@kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] hfs: validate drAlBlkSiz and fs_ablocks in hfs_mdb_get() Date: Sat, 19 Sep 2026 22:26:05 +0000 Message-ID: <20260919222605.3794529-1-benquike@gmail.com> X-Mailer: git-send-email 2.55.0.1082.g2b9226bbc0-goog Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit In hfs_mdb_get() (fs/hfs/mdb.c), reject images with allocation block size (drAlBlkSiz) of 0 or not a multiple of HFS_SECTOR_SIZE (512), or with fs_ablocks == 0, preventing a divide-by-zero trap and out-of-bounds bitmap scans on crafted HFS images. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Assisted-by: LLM Signed-off-by: Hui Peng --- diff --git a/fs/hfs/mdb.c b/fs/hfs/mdb.c index 277de712f9d4..9e78c561a3f1 100644 --- a/fs/hfs/mdb.c +++ b/fs/hfs/mdb.c @@ -204,6 +204,11 @@ int hfs_mdb_get(struct super_block *sb) /* These parameters are read from the MDB, and never written */ HFS_SB(sb)->part_start = part_start; HFS_SB(sb)->fs_ablocks = be16_to_cpu(mdb->drNmAlBlks); + if (!HFS_SB(sb)->fs_ablocks) { + brelse(bh); + HFS_SB(sb)->mdb_bh = NULL; + return -EINVAL; + } HFS_SB(sb)->fs_div = HFS_SB(sb)->alloc_blksz >> sb->s_blocksize_bits; HFS_SB(sb)->clumpablks = be32_to_cpu(mdb->drClpSiz) / HFS_SB(sb)->alloc_blksz;