From ab4ba2e133463c702b37242560d7fabedd2dc750 Mon Sep 17 00:00:00 2001
From: Qu Wenruo <wqu@suse.com>
Date: Fri, 8 Mar 2019 14:20:03 +0800
Git-commit: ab4ba2e133463c702b37242560d7fabedd2dc750
References: dependency for bsc#1157692
Patch-mainline: v5.2
Subject: [PATCH 05/22] btrfs: tree-checker: Verify dev item
[BUG]
For fuzzed image whose DEV_ITEM has invalid total_bytes as 0, then
kernel will just panic:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000098
#PF error: [normal kernel read fault]
PGD 800000022b2bd067 P4D 800000022b2bd067 PUD 22b2bc067 PMD 0
Oops: 0000 [#1] SMP PTI
CPU: 0 PID: 1106 Comm: mount Not tainted 5.0.0-rc8+ #9
RIP: 0010:btrfs_verify_dev_extents+0x2a5/0x5a0
Call Trace:
open_ctree+0x160d/0x2149
btrfs_mount_root+0x5b2/0x680
[CAUSE]
If device extent verification finds a deivce with 0 total_bytes, then it
assumes it's a seed dummy, then search for seed devices.
But in this case, there is no seed device at all, causing NULL pointer.
[FIX]
Since this is caused by fuzzed image, let's go the tree-check way, just
add a new verification for device item.
Reported-by: Yoon Jungyeon <jungyeon@gatech.edu>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=202691
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>
---
fs/btrfs/tree-checker.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++++
fs/btrfs/volumes.c | 13 +-------
fs/btrfs/volumes.h | 9 +++++
3 files changed, 85 insertions(+), 11 deletions(-)
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -608,6 +608,77 @@ int btrfs_check_chunk_valid(struct btrfs
return 0;
}
+__printf(4, 5)
+__cold
+static void dev_item_err(const struct btrfs_fs_info *fs_info,
+ const struct extent_buffer *eb, int slot,
+ const char *fmt, ...)
+{
+ struct btrfs_key key;
+ struct va_format vaf;
+ va_list args;
+
+ btrfs_item_key_to_cpu(eb, &key, slot);
+ va_start(args, fmt);
+
+ vaf.fmt = fmt;
+ vaf.va = &args;
+
+ btrfs_crit(fs_info,
+ "corrupt %s: root=%llu block=%llu slot=%d devid=%llu %pV",
+ btrfs_header_level(eb) == 0 ? "leaf" : "node",
+ btrfs_header_owner(eb), btrfs_header_bytenr(eb), slot,
+ key.objectid, &vaf);
+ va_end(args);
+}
+
+static int check_dev_item(struct btrfs_fs_info *fs_info,
+ struct extent_buffer *leaf,
+ struct btrfs_key *key, int slot)
+{
+ struct btrfs_dev_item *ditem;
+ u64 max_devid = max(BTRFS_MAX_DEVS(fs_info), BTRFS_MAX_DEVS_SYS_CHUNK);
+
+ if (key->objectid != BTRFS_DEV_ITEMS_OBJECTID) {
+ dev_item_err(fs_info, leaf, slot,
+ "invalid objectid: has=%llu expect=%llu",
+ key->objectid, BTRFS_DEV_ITEMS_OBJECTID);
+ return -EUCLEAN;
+ }
+ if (key->offset > max_devid) {
+ dev_item_err(fs_info, leaf, slot,
+ "invalid devid: has=%llu expect=[0, %llu]",
+ key->offset, max_devid);
+ return -EUCLEAN;
+ }
+ ditem = btrfs_item_ptr(leaf, slot, struct btrfs_dev_item);
+ if (btrfs_device_id(leaf, ditem) != key->offset) {
+ dev_item_err(fs_info, leaf, slot,
+ "devid mismatch: key has=%llu item has=%llu",
+ key->offset, btrfs_device_id(leaf, ditem));
+ return -EUCLEAN;
+ }
+
+ /*
+ * For device total_bytes, we don't have reliable way to check it, as
+ * it can be 0 for device removal. Device size check can only be done
+ * by dev extents check.
+ */
+ if (btrfs_device_bytes_used(leaf, ditem) >
+ btrfs_device_total_bytes(leaf, ditem)) {
+ dev_item_err(fs_info, leaf, slot,
+ "invalid bytes used: have %llu expect [0, %llu]",
+ btrfs_device_bytes_used(leaf, ditem),
+ btrfs_device_total_bytes(leaf, ditem));
+ return -EUCLEAN;
+ }
+ /*
+ * Remaining members like io_align/type/gen/dev_group aren't really
+ * utilized. Skip them to make later usage of them easier.
+ */
+ return 0;
+}
+
/*
* Common point to switch the item-specific validation.
*/
@@ -638,6 +709,9 @@ static int check_leaf_item(struct btrfs_
ret = btrfs_check_chunk_valid(fs_info, leaf, chunk,
key->offset);
break;
+ case BTRFS_DEV_ITEM_KEY:
+ ret = check_dev_item(fs_info, leaf, key, slot);
+ break;
}
return ret;
}
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4700,15 +4700,6 @@ static void check_raid56_incompat_flag(s
btrfs_set_fs_incompat(info, RAID56);
}
-#define BTRFS_MAX_DEVS(r) ((BTRFS_MAX_ITEM_SIZE(r->fs_info) \
- - sizeof(struct btrfs_chunk)) \
- / sizeof(struct btrfs_stripe) + 1)
-
-#define BTRFS_MAX_DEVS_SYS_CHUNK ((BTRFS_SYSTEM_CHUNK_ARRAY_SIZE \
- - 2 * sizeof(struct btrfs_disk_key) \
- - 2 * sizeof(struct btrfs_chunk)) \
- / sizeof(struct btrfs_stripe) + 1)
-
static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
u64 start, u64 type)
{
@@ -4758,7 +4749,7 @@ static int __btrfs_alloc_chunk(struct bt
max_stripe_size = SZ_1G;
max_chunk_size = BTRFS_MAX_DATA_CHUNK_SIZE;
if (!devs_max)
- devs_max = BTRFS_MAX_DEVS(info->chunk_root);
+ devs_max = BTRFS_MAX_DEVS(info);
} else if (type & BTRFS_BLOCK_GROUP_METADATA) {
/* for larger filesystems, use larger metadata chunks */
if (fs_devices->total_rw_bytes > 50ULL * SZ_1G)
@@ -4767,7 +4758,7 @@ static int __btrfs_alloc_chunk(struct bt
max_stripe_size = SZ_256M;
max_chunk_size = max_stripe_size;
if (!devs_max)
- devs_max = BTRFS_MAX_DEVS(info->chunk_root);
+ devs_max = BTRFS_MAX_DEVS(info);
} else if (type & BTRFS_BLOCK_GROUP_SYSTEM) {
max_stripe_size = SZ_32M;
max_chunk_size = 2 * max_stripe_size;
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -263,6 +263,15 @@ struct btrfs_fs_devices {
#define BTRFS_BIO_INLINE_CSUM_SIZE 64
+#define BTRFS_MAX_DEVS(info) ((BTRFS_MAX_ITEM_SIZE(info) \
+ - sizeof(struct btrfs_chunk)) \
+ / sizeof(struct btrfs_stripe) + 1)
+
+#define BTRFS_MAX_DEVS_SYS_CHUNK ((BTRFS_SYSTEM_CHUNK_ARRAY_SIZE \
+ - 2 * sizeof(struct btrfs_disk_key) \
+ - 2 * sizeof(struct btrfs_chunk)) \
+ / sizeof(struct btrfs_stripe) + 1)
+
/*
* we need the mirror number and stripe index to be passed around
* the call chain while we are processing end_io (especially errors).