Re: git: c718009884b3 - main - vm_map.c: plug several more places which might modify entry->offset

> On 18. Aug 2023, at 14:44, Konstantin Belousov <kib@FreeBSD.org> wrote:
> 
> The branch main has been updated by kib:
> 
> URL: https://cgit.FreeBSD.org/src/commit/?id=c718009884b3d65528deaff24712cbf98e3be656
> 
> commit c718009884b3d65528deaff24712cbf98e3be656
> Author:     Konstantin Belousov <kib@FreeBSD.org>
> AuthorDate: 2023-08-15 19:05:33 +0000
> Commit:     Konstantin Belousov <kib@FreeBSD.org>
> CommitDate: 2023-08-18 12:43:35 +0000
> 
>   vm_map.c: plug several more places which might modify entry->offset
> 
>   for the GUARD entries protecting stacks gaps.
> 
>   syzkaller: https://syzkaller.appspot.com/bug?extid=c325d6a75e4fd0a68714
>   Reviewed by:    dougm, markj (previous version)
>   Tested by:      pho (previous version)
>   Sponsored by:   The FreeBSD Foundation
>   MFC after:      1 week
>   Differential revision:  https://reviews.freebsd.org/D41475
> ---
> sys/vm/vm_map.c | 13 ++++++++++---
> 1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c
> index 252b58ad2924..f609d1fd68d7 100644
> --- a/sys/vm/vm_map.c
> +++ b/sys/vm/vm_map.c
> @@ -1413,7 +1413,9 @@ vm_map_entry_link(vm_map_t map, vm_map_entry_t entry)
> KASSERT(entry->end < root->end,
>   ("%s: clip_start not within entry", __func__));
> vm_map_splay_findprev(root, &llist);
> - root->offset += entry->end - root->start;
> + if ((root->eflags & (MAP_ENTRY_STACK_GAP_DN |
> +    MAP_ENTRY_STACK_GAP_UP)) == 0)
> + root->offset += entry->end - root->start;
> root->start = entry->end;
> max_free_left = vm_map_splay_merge_pred(header, entry, llist);
> max_free_right = root->max_free = vm_size_max(
> @@ -1429,7 +1431,9 @@ vm_map_entry_link(vm_map_t map, vm_map_entry_t entry)
> KASSERT(entry->end == root->end,
>   ("%s: clip_start not within entry", __func__));
> vm_map_splay_findnext(root, &rlist);
> - entry->offset += entry->start - root->start;
> + if ((entry->eflags & (MAP_ENTRY_STACK_GAP_DN |
> +    MAP_ENTRY_STACK_GAP_UP)) == 0)
> + entry->offset += entry->start - root->start;
> root->end = entry->start;
> max_free_left = root->max_free = vm_size_max(
>   vm_map_splay_merge_left(header, root, llist),
> @@ -1463,6 +1467,8 @@ vm_map_entry_unlink(vm_map_t map, vm_map_entry_t entry,
> vm_map_splay_findnext(root, &rlist);
> if (op == UNLINK_MERGE_NEXT) {
> rlist->start = root->start;
> + MPASS((rlist->eflags & (MAP_ENTRY_STACK_GAP_DN |
> +    MAP_ENTRY_STACK_GAP_UP) == 0);
This breaks compilation. I guess it should be

+ MPASS((rlist->eflags & (MAP_ENTRY_STACK_GAP_DN |
+    MAP_ENTRY_STACK_GAP_UP)) == 0);

Best regards
Michael

> rlist->offset = root->offset;
> }
> if (llist != header) {
> @@ -3103,7 +3109,8 @@ vm_map_madvise(
>   entry = vm_map_entry_succ(entry)) {
> vm_offset_t useEnd, useStart;
> 
> - if ((entry->eflags & MAP_ENTRY_IS_SUB_MAP) != 0)
> + if ((entry->eflags & (MAP_ENTRY_IS_SUB_MAP |
> +    MAP_ENTRY_GUARD)) != 0)
> continue;
> 
> /*