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Auke Kok
70b80695cb
Scoutfs print segfaults walking a log_merge btree that has more than one level. print_btree_block() prints parent (level > 0) items via print_block_ref(), which invokes the item callback with a NULL value to print the key portion before printing the child ref: func(key, 0, 0, NULL, 0, arg); print_log_merge_item immediately casts val and reads a field, dereferencing NULL. A log_merge of a single leaf block (height 1) never hits the parent path; one with height > 1 crashes on the first parent item: scoutfs[22043]: segfault at 8 ip 0000000000408ef0 sp 00007fffc5edd8b0 error 4 #0 0x0000000000408ef0 in print_log_merge_item () #1 0x000000000040958d in print_btree_block.constprop.0.isra () #2 0x000000000040a471 in print_cmd () #3 0x0000000000404264 in cmd_execute () #4 0x00000000004025c9 in main () print_mounted_client_entry has the same bug: it casts val and reads mcv->addr / mcv->flags with no NULL guard, so a mounted_clients btree of height > 1 segfaults the same way. print_srch_root_item guards NULL but casts to scoutfs_srch_compact or scoutfs_srch_file without bounds checking, so a short or malformed item reads past its end. Fix all three: return early when val is NULL (printing just the key for the parent ref where applicable), and bounds-check val_len before each cast so a short item is reported instead of read past its end. Signed-off-by: Auke Kok <auke.kok@versity.com>
Introduction
scoutfs is a clustered in-kernel Linux filesystem designed to support large archival systems. It features additional interfaces and metadata so that archive agents can perform their maintenance workflows without walking all the files in the namespace. Its cluster support lets deployments add nodes to satisfy archival tier bandwidth targets.
The design goal is to reach file populations in the trillions, with the archival bandwidth to match, while remaining operational and responsive.
Highlights of the design and implementation include:
- Fully consistent POSIX semantics between nodes
- Atomic transactions to maintain consistent persistent structures
- Integrated archival metadata replaces syncing to external databases
- Dynamic seperation of resources lets nodes write in parallel
- 64bit throughout; no limits on file or directory sizes or counts
- Open GPLv2 implementation
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