forked from luck/tmp_suning_uos_patched
e7c9559300
When mounting an ext4 filesystem with corrupted s_first_data_block, things
can go very wrong and oops.
Because blocks_count in ext4_fill_super is a u64, and we must use do_div,
the calculation of db_count is done differently than on ext4. If
first_data_block is corrupted such that it is larger than ext4_blocks_count,
for example, then the intermediate blocks_count value may go negative,
but sign-extend to a very large value:
blocks_count = (ext4_blocks_count(es) -
le32_to_cpu(es->s_first_data_block) +
EXT4_BLOCKS_PER_GROUP(sb) - 1);
This is then assigned to s_groups_count which is an unsigned long:
sbi->s_groups_count = blocks_count;
This may result in a value of 0xFFFFFFFF which is then used to compute
db_count:
db_count = (sbi->s_groups_count + EXT4_DESC_PER_BLOCK(sb) - 1) /
EXT4_DESC_PER_BLOCK(sb);
and in this case db_count will wind up as 0 because the addition overflows
32 bits. This in turn causes the kmalloc for group_desc to be of 0 size:
sbi->s_group_desc = kmalloc(db_count * sizeof (struct buffer_head *),
GFP_KERNEL);
and eventually in ext4_check_descriptors, dereferencing
sbi->s_group_desc[desc_block] will result in a NULL pointer dereference.
The simplest test seems to be to sanity check s_first_data_block,
EXT4_BLOCKS_PER_GROUP, and ext4_blocks_count values to be sure
their combination won't result in a bad intermediate value for
blocks_count. We could just check for db_count == 0, but
catching it at the root cause seems like it provides more info.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Mingming Cao <cmm@us.ibm.com>
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| .. | ||
| 9p | ||
| adfs | ||
| affs | ||
| afs | ||
| autofs | ||
| autofs4 | ||
| befs | ||
| bfs | ||
| cifs | ||
| coda | ||
| configfs | ||
| cramfs | ||
| debugfs | ||
| devpts | ||
| dlm | ||
| ecryptfs | ||
| efs | ||
| exportfs | ||
| ext2 | ||
| ext3 | ||
| ext4 | ||
| fat | ||
| freevxfs | ||
| fuse | ||
| gfs2 | ||
| hfs | ||
| hfsplus | ||
| hostfs | ||
| hpfs | ||
| hppfs | ||
| hugetlbfs | ||
| isofs | ||
| jbd | ||
| jbd2 | ||
| jffs2 | ||
| jfs | ||
| lockd | ||
| minix | ||
| msdos | ||
| ncpfs | ||
| nfs | ||
| nfs_common | ||
| nfsd | ||
| nls | ||
| ntfs | ||
| ocfs2 | ||
| openpromfs | ||
| partitions | ||
| proc | ||
| qnx4 | ||
| ramfs | ||
| reiserfs | ||
| romfs | ||
| smbfs | ||
| sysfs | ||
| sysv | ||
| udf | ||
| ufs | ||
| vfat | ||
| xfs | ||
| aio.c | ||
| anon_inodes.c | ||
| attr.c | ||
| bad_inode.c | ||
| binfmt_aout.c | ||
| binfmt_elf_fdpic.c | ||
| binfmt_elf.c | ||
| binfmt_em86.c | ||
| binfmt_flat.c | ||
| binfmt_misc.c | ||
| binfmt_script.c | ||
| binfmt_som.c | ||
| bio.c | ||
| block_dev.c | ||
| buffer.c | ||
| char_dev.c | ||
| compat_ioctl.c | ||
| compat.c | ||
| dcache.c | ||
| dcookies.c | ||
| direct-io.c | ||
| dnotify.c | ||
| dquot.c | ||
| drop_caches.c | ||
| eventfd.c | ||
| eventpoll.c | ||
| exec.c | ||
| fcntl.c | ||
| fifo.c | ||
| file_table.c | ||
| file.c | ||
| filesystems.c | ||
| fs-writeback.c | ||
| generic_acl.c | ||
| inode.c | ||
| inotify_user.c | ||
| inotify.c | ||
| internal.h | ||
| ioctl.c | ||
| ioprio.c | ||
| Kconfig | ||
| Kconfig.binfmt | ||
| libfs.c | ||
| locks.c | ||
| Makefile | ||
| mbcache.c | ||
| mpage.c | ||
| namei.c | ||
| namespace.c | ||
| nfsctl.c | ||
| no-block.c | ||
| open.c | ||
| pipe.c | ||
| pnode.c | ||
| pnode.h | ||
| posix_acl.c | ||
| quota_v1.c | ||
| quota_v2.c | ||
| quota.c | ||
| read_write.c | ||
| read_write.h | ||
| readdir.c | ||
| select.c | ||
| seq_file.c | ||
| signalfd.c | ||
| splice.c | ||
| stack.c | ||
| stat.c | ||
| super.c | ||
| sync.c | ||
| timerfd.c | ||
| utimes.c | ||
| xattr_acl.c | ||
| xattr.c | ||