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btrfs-progs: show-super: copy implementation of btrfs_read_sys_array

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btrfs-show-super has own implementation to read the sys array and it
lacks all the sanity checks.

Copy and adapt the improved implementation from btrfs_read_sys_array.
This will fix crashes on a fuzzed/corrupted images. It's duplicating
code but at the moment looks easier than refactoring and restructuring
btrfs_read_sys_array that now almost matches the kernel code, which we
want in the long term.

Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2015-11-30 17:56:58 +01:00
parent 5f03d1fc23
commit 88f584cfea
1 changed files with 54 additions and 15 deletions
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69
btrfs-show-super.c
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@ -186,11 +186,14 @@ static void print_sys_chunk_array(struct btrfs_super_block *sb)
struct extent_buffer *buf;
struct btrfs_disk_key *disk_key;
struct btrfs_chunk *chunk;
struct btrfs_key key;
u8 *ptr, *array_end;
u8 *array_ptr;
unsigned long sb_array_offset;
u32 num_stripes;
u32 array_size;
u32 len = 0;
int i = 0;
u32 cur_offset;
struct btrfs_key key;
int item;
buf = malloc(sizeof(*buf) + sizeof(*sb));
if (!buf) {
@ -198,34 +201,70 @@ static void print_sys_chunk_array(struct btrfs_super_block *sb)
exit(1);
}
write_extent_buffer(buf, sb, 0, sizeof(*sb));
ptr = sb->sys_chunk_array;
array_end = ptr + btrfs_super_sys_array_size(sb);
array_size = btrfs_super_sys_array_size(sb);
array_ptr = sb->sys_chunk_array;
sb_array_offset = offsetof(struct btrfs_super_block, sys_chunk_array);
cur_offset = 0;
item = 0;
while (cur_offset < array_size) {
disk_key = (struct btrfs_disk_key *)array_ptr;
len = sizeof(*disk_key);
if (cur_offset + len > array_size)
goto out_short_read;
while (ptr < array_end) {
disk_key = (struct btrfs_disk_key *)ptr;
btrfs_disk_key_to_cpu(&key, disk_key);
printf("\titem %d ", i);
btrfs_print_key(disk_key);
array_ptr += len;
sb_array_offset += len;
cur_offset += len;
len = sizeof(*disk_key);
printf("\titem %d ", item);
btrfs_print_key(disk_key);
putchar('\n');
ptr += len;
if (key.type == BTRFS_CHUNK_ITEM_KEY) {
chunk = (struct btrfs_chunk *)(ptr - (u8 *)sb);
chunk = (struct btrfs_chunk *)sb_array_offset;
/*
* At least one btrfs_chunk with one stripe must be
* present, exact stripe count check comes afterwards
*/
len = btrfs_chunk_item_size(1);
if (cur_offset + len > array_size)
goto out_short_read;
print_chunk(buf, chunk);
num_stripes = btrfs_chunk_num_stripes(buf, chunk);
if (!num_stripes) {
printk(
"ERROR: invalid number of stripes %u in sys_array at offset %u\n",
num_stripes, cur_offset);
break;
}
len = btrfs_chunk_item_size(num_stripes);
if (cur_offset + len > array_size)
goto out_short_read;
} else {
BUG();
printk(
"ERROR: unexpected item type %u in sys_array at offset %u\n",
(u32)key.type, cur_offset);
break;
}
array_ptr += len;
sb_array_offset += len;
cur_offset += len;
ptr += len;
i++;
item++;
}
free(buf);
return;
out_short_read:
printk("ERROR: sys_array too short to read %u bytes at offset %u\n",
len, cur_offset);
free(buf);
}
static int empty_backup(struct btrfs_root_backup *backup)