From ecd3d7c8a9f7dc56320c6bba9c43f7b769bacb66 Mon Sep 17 00:00:00 2001 From: kib Date: Sat, 18 Feb 2012 00:49:09 +0000 Subject: [PATCH 105/175] MFC r231526: Close a race due to dropping of the map lock between creating map entry for a shared mapping and marking the entry for inheritance. git-svn-id: http://svn.freebsd.org/base/stable/9@231889 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f (cherry picked from commit af29713dd40fbabf77a7e29c76e5b75a71139012) Signed-off-by: Xin Li --- sys/vm/vm_map.c | 9 +++++++-- sys/vm/vm_map.h | 2 +- sys/vm/vm_mmap.c | 10 +++------- 3 files changed, 11 insertions(+), 10 deletions(-) diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c index d62576f..0c98d56 100644 --- a/sys/vm/vm_map.c +++ b/sys/vm/vm_map.c @@ -1130,6 +1130,7 @@ vm_map_insert(vm_map_t map, vm_object_t object, vm_ooffset_t offset, vm_map_entry_t temp_entry; vm_eflags_t protoeflags; struct ucred *cred; + vm_inherit_t inheritance; boolean_t charge_prev_obj; VM_MAP_ASSERT_LOCKED(map); @@ -1173,6 +1174,10 @@ vm_map_insert(vm_map_t map, vm_object_t object, vm_ooffset_t offset, protoeflags |= MAP_ENTRY_NOSYNC; if (cow & MAP_DISABLE_COREDUMP) protoeflags |= MAP_ENTRY_NOCOREDUMP; + if (cow & MAP_INHERIT_SHARE) + inheritance = VM_INHERIT_SHARE; + else + inheritance = VM_INHERIT_DEFAULT; cred = NULL; KASSERT((object != kmem_object && object != kernel_object) || @@ -1227,7 +1232,7 @@ charged: * can extend the previous map entry to include the * new range as well. */ - if ((prev_entry->inheritance == VM_INHERIT_DEFAULT) && + if ((prev_entry->inheritance == inheritance) && (prev_entry->protection == prot) && (prev_entry->max_protection == max)) { map->size += (end - prev_entry->end); @@ -1276,7 +1281,7 @@ charged: new_entry->offset = offset; new_entry->avail_ssize = 0; - new_entry->inheritance = VM_INHERIT_DEFAULT; + new_entry->inheritance = inheritance; new_entry->protection = prot; new_entry->max_protection = max; new_entry->wired_count = 0; diff --git a/sys/vm/vm_map.h b/sys/vm/vm_map.h index 5311e02..11ff632 100644 --- a/sys/vm/vm_map.h +++ b/sys/vm/vm_map.h @@ -307,7 +307,7 @@ long vmspace_wired_count(struct vmspace *vmspace); /* * Copy-on-write flags for vm_map operations */ -#define MAP_UNUSED_01 0x0001 +#define MAP_INHERIT_SHARE 0x0001 #define MAP_COPY_ON_WRITE 0x0002 #define MAP_NOFAULT 0x0004 #define MAP_PREFAULT 0x0008 diff --git a/sys/vm/vm_mmap.c b/sys/vm/vm_mmap.c index e85b681..4b4996f 100644 --- a/sys/vm/vm_mmap.c +++ b/sys/vm/vm_mmap.c @@ -1517,6 +1517,9 @@ vm_mmap(vm_map_t map, vm_offset_t *addr, vm_size_t size, vm_prot_t prot, docow |= MAP_DISABLE_SYNCER; if (flags & MAP_NOCORE) docow |= MAP_DISABLE_COREDUMP; + /* Shared memory is also shared with children. */ + if (flags & MAP_SHARED) + docow |= MAP_INHERIT_SHARE; if (flags & MAP_STACK) rv = vm_map_stack(map, *addr, size, prot, maxprot, @@ -1536,13 +1539,6 @@ vm_mmap(vm_map_t map, vm_offset_t *addr, vm_size_t size, vm_prot_t prot, * or named anonymous without other references. */ vm_object_deallocate(object); - } else if (flags & MAP_SHARED) { - /* - * Shared memory is also shared with children. - */ - rv = vm_map_inherit(map, *addr, *addr + size, VM_INHERIT_SHARE); - if (rv != KERN_SUCCESS) - (void) vm_map_remove(map, *addr, *addr + size); } /* -- 1.7.9.4