Subject: Avoid disk sector_t overflow for >2TB ext3 filesystem From: Mingming Cao If ext3 filesystem is larger than 2TB, and sector_t is a u32 (i.e. CONFIG_LBD not defined in the kernel), the calculation of the disk sector will overflow. Add check at ext3_fill_super() and ext3_group_extend() to prevent mount/remount/resize >2TB ext3 filesystem if sector_t size is 4 bytes. Verified this patch on a 32 bit platform without CONFIG_LBD defined (sector_t is 32 bits long), mount refuse to mount a 10TB ext3. Signed-off-by: Mingming Cao Acked-by: Andreas Dilger Signed-off-by: Andrew Morton --- fs/ext3/resize.c | 10 ++++++++++ fs/ext3/super.c | 10 ++++++++++ 2 files changed, 20 insertions(+) diff -puN fs/ext3/resize.c~avoid-disk-sector_t-overflow-for-2tb-ext3-filesystem fs/ext3/resize.c --- devel/fs/ext3/resize.c~avoid-disk-sector_t-overflow-for-2tb-ext3-filesystem 2006-05-22 14:09:53.000000000 -0700 +++ devel-akpm/fs/ext3/resize.c 2006-05-22 14:10:56.000000000 -0700 @@ -926,6 +926,16 @@ int ext3_group_extend(struct super_block if (n_blocks_count == 0 || n_blocks_count == o_blocks_count) return 0; + if (n_blocks_count > (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) { + printk(KERN_ERR "EXT3-fs: filesystem on %s: " + "too large to resize to %lu blocks safely\n", + sb->s_id, n_blocks_count); + if (sizeof(sector_t) < 8) + ext3_warning(sb, __FUNCTION__, + "CONFIG_LBD not enabled\n"); + return -EINVAL; + } + if (n_blocks_count < o_blocks_count) { ext3_warning(sb, __FUNCTION__, "can't shrink FS - resize aborted"); diff -puN fs/ext3/super.c~avoid-disk-sector_t-overflow-for-2tb-ext3-filesystem fs/ext3/super.c --- devel/fs/ext3/super.c~avoid-disk-sector_t-overflow-for-2tb-ext3-filesystem 2006-05-22 14:09:53.000000000 -0700 +++ devel-akpm/fs/ext3/super.c 2006-05-22 14:11:10.000000000 -0700 @@ -1565,6 +1565,17 @@ static int ext3_fill_super (struct super goto failed_mount; } + if (le32_to_cpu(es->s_blocks_count) > + (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) { + printk(KERN_ERR "EXT3-fs: filesystem on %s: " + "too large to mount safely - %u blocks\n", sb->s_id, + le32_to_cpu(es->s_blocks_count)); + if (sizeof(sector_t) < 8) + printk(KERN_WARNING + "EXT3-fs: CONFIG_LBD not enabled\n"); + goto failed_mount; + } + if (EXT3_BLOCKS_PER_GROUP(sb) == 0) goto cantfind_ext3; sbi->s_groups_count = (le32_to_cpu(es->s_blocks_count) - _