Date: Fri, 25 Aug 2023 01:08:37 GMT From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: d5fccc19aa1b - stable/13 - vm_map_protect(): add VM_MAP_PROTECT_GROWSDOWN flag Message-ID: <202308250108.37P18bdd058508@gitrepo.freebsd.org>
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The branch stable/13 has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=d5fccc19aa1b1e9440b5ad3bc386b6bb42fdff78 commit d5fccc19aa1b1e9440b5ad3bc386b6bb42fdff78 Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2023-07-28 00:40:53 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2023-08-25 01:06:44 +0000 vm_map_protect(): add VM_MAP_PROTECT_GROWSDOWN flag (cherry picked from commit 90049eabcfadf229e3983f04310a8ea28fe3d2b1) --- sys/vm/vm_map.c | 19 +++++++++++++++++++ sys/vm/vm_map.h | 1 + 2 files changed, 20 insertions(+) diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c index 1f223bbbd396..029605eb272a 100644 --- a/sys/vm/vm_map.c +++ b/sys/vm/vm_map.c @@ -2752,6 +2752,7 @@ vm_map_protect(vm_map_t map, vm_offset_t start, vm_offset_t end, vm_map_entry_t entry, first_entry, in_tran, prev_entry; vm_object_t obj; struct ucred *cred; + vm_offset_t orig_start; vm_prot_t check_prot, max_prot, old_prot; int rv; @@ -2763,8 +2764,10 @@ vm_map_protect(vm_map_t map, vm_offset_t start, vm_offset_t end, !CONTAINS_BITS(new_maxprot, new_prot)) return (KERN_OUT_OF_BOUNDS); + orig_start = start; again: in_tran = NULL; + start = orig_start; vm_map_lock(map); if ((map->flags & MAP_WXORX) != 0 && @@ -2787,6 +2790,22 @@ again: if (!vm_map_lookup_entry(map, start, &first_entry)) first_entry = vm_map_entry_succ(first_entry); + if ((flags & VM_MAP_PROTECT_GROWSDOWN) != 0 && + (first_entry->eflags & MAP_ENTRY_GROWS_DOWN) != 0) { + /* + * Handle Linux's PROT_GROWSDOWN flag. + * It means that protection is applied down to the + * whole stack, including the specified range of the + * mapped region, and the grow down region (AKA + * guard). + */ + while (!CONTAINS_BITS(first_entry->eflags, + MAP_ENTRY_GUARD | MAP_ENTRY_STACK_GAP_DN) && + first_entry != vm_map_entry_first(map)) + first_entry = vm_map_entry_pred(first_entry); + start = first_entry->start; + } + /* * Make a first pass to check for protection violations. */ diff --git a/sys/vm/vm_map.h b/sys/vm/vm_map.h index 8adfcaf57cb3..9e4e1db0fd98 100644 --- a/sys/vm/vm_map.h +++ b/sys/vm/vm_map.h @@ -518,6 +518,7 @@ vm_map_entry_succ(vm_map_entry_t entry) #define VM_MAP_PROTECT_SET_PROT 0x0001 #define VM_MAP_PROTECT_SET_MAXPROT 0x0002 +#define VM_MAP_PROTECT_GROWSDOWN 0x0004 int vm_map_protect(vm_map_t map, vm_offset_t start, vm_offset_t end, vm_prot_t new_prot, vm_prot_t new_maxprot, int flags);
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