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X-BeenThere: barebox@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Claude Opus 4.6 \(1M context\)" Sender: "barebox" X-SA-Exim-Connect-IP: 2607:7c80:54:3::133 X-SA-Exim-Mail-From: barebox-bounces+lore=pengutronix.de@lists.infradead.org X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on metis.whiteo.stw.pengutronix.de X-Spam-Level: X-Spam-Status: No, score=-5.2 required=4.0 tests=AWL,BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.2 Subject: [PATCH 2/5] fs: ext4: reject superblocks with zero inodesz, gdsize or inodes_per_group X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on metis.whiteo.stw.pengutronix.de) The superblock fields inode_size, descriptor_size, and inodes_per_group are read from disk and used as divisors without validation: - inodesz == 0: division by zero in ext4fs_read_inode() - gdsize == 0: division by zero in ext4fs_blockgroup() - inodes_per_group == 0: division by zero in ext4fs_read_inode() All three are trivially triggered by a crafted filesystem image. Validate these fields are non-zero at mount time and reject the filesystem if they aren't. Signed-off-by: Sascha Hauer Co-Authored-By: Claude Opus 4.6 (1M context) --- fs/ext4/ext4_common.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c index 094293a069..5d252b4a2c 100644 --- a/fs/ext4/ext4_common.c +++ b/fs/ext4/ext4_common.c @@ -541,6 +541,15 @@ int ext4fs_mount(struct ext_filesystem *fs) le32_to_cpu(data->sblock.revision_level), fs->inodesz, fs->gdsize); + if (!fs->inodesz || !fs->gdsize || + !le32_to_cpu(data->sblock.inodes_per_group)) { + dev_err(fs->dev, "invalid superblock: inodesz=%u gdsize=%u inodes_per_group=%u\n", + fs->inodesz, fs->gdsize, + le32_to_cpu(data->sblock.inodes_per_group)); + ret = -EINVAL; + goto fail; + } + data->diropen.data = data; data->diropen.ino = 2; data->diropen.inode_read = 1; -- 2.47.3