Date: Mon, 17 Apr 2017 16:59:19 +0000 (UTC) From: Mark Johnston <markj@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Subject: svn commit: r317054 - stable/11/sys/vm Message-ID: <201704171659.v3HGxJ8m006651@repo.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: markj Date: Mon Apr 17 16:59:18 2017 New Revision: 317054 URL: https://svnweb.freebsd.org/changeset/base/317054 Log: MFC r316686, r316687, r316689 Fix a race between vm_map_wire() and vm_map_protect(). Modified: stable/11/sys/vm/vm_map.c Directory Properties: stable/11/ (props changed) Modified: stable/11/sys/vm/vm_map.c ============================================================================== --- stable/11/sys/vm/vm_map.c Mon Apr 17 16:51:04 2017 (r317053) +++ stable/11/sys/vm/vm_map.c Mon Apr 17 16:59:18 2017 (r317054) @@ -1655,6 +1655,8 @@ _vm_map_clip_start(vm_map_t map, vm_map_ vm_map_entry_t new_entry; VM_MAP_ASSERT_LOCKED(map); + KASSERT(entry->end > start && entry->start < start, + ("_vm_map_clip_start: invalid clip of entry %p", entry)); /* * Split off the front portion -- note that we must insert the new @@ -1739,6 +1741,8 @@ _vm_map_clip_end(vm_map_t map, vm_map_en vm_map_entry_t new_entry; VM_MAP_ASSERT_LOCKED(map); + KASSERT(entry->start < end && entry->end > end, + ("_vm_map_clip_end: invalid clip of entry %p", entry)); /* * If there is no object backing this entry, we might as well create @@ -1963,6 +1967,14 @@ vm_map_protect(vm_map_t map, vm_offset_t vm_map_lock(map); + /* + * Ensure that we are not concurrently wiring pages. vm_map_wire() may + * need to fault pages into the map and will drop the map lock while + * doing so, and the VM object may end up in an inconsistent state if we + * update the protection on the map entry in between faults. + */ + vm_map_wait_busy(map); + VM_MAP_RANGE_CHECK(map, start, end); if (vm_map_lookup_entry(map, start, &entry)) { @@ -1974,8 +1986,8 @@ vm_map_protect(vm_map_t map, vm_offset_t /* * Make a first pass to check for protection violations. */ - current = entry; - while ((current != &map->header) && (current->start < end)) { + for (current = entry; current != &map->header && current->start < end; + current = current->next) { if (current->eflags & MAP_ENTRY_IS_SUB_MAP) { vm_map_unlock(map); return (KERN_INVALID_ARGUMENT); @@ -1984,17 +1996,15 @@ vm_map_protect(vm_map_t map, vm_offset_t vm_map_unlock(map); return (KERN_PROTECTION_FAILURE); } - current = current->next; } - /* * Do an accounting pass for private read-only mappings that * now will do cow due to allowed write (e.g. debugger sets * breakpoint on text segment) */ - for (current = entry; (current != &map->header) && - (current->start < end); current = current->next) { + for (current = entry; current != &map->header && current->start < end; + current = current->next) { vm_map_clip_end(map, current, end); @@ -2047,8 +2057,8 @@ vm_map_protect(vm_map_t map, vm_offset_t * Go back and fix up protections. [Note that clipping is not * necessary the second time.] */ - current = entry; - while ((current != &map->header) && (current->start < end)) { + for (current = entry; current != &map->header && current->start < end; + current = current->next) { old_prot = current->protection; if (set_max) @@ -2082,7 +2092,6 @@ vm_map_protect(vm_map_t map, vm_offset_t #undef MASK } vm_map_simplify_entry(map, current); - current = current->next; } vm_map_unlock(map); return (KERN_SUCCESS);
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201704171659.v3HGxJ8m006651>