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Clear the MAP_WIREFUTURE flag on the vm map in exec_new_vmspace() when it

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recycles the current vm space.  Otherwise, an mlockall(MCL_FUTURE) could
still be in effect on the process after an execve(2), which violates the
specification for mlockall(2).

It's pointless for vm_map_stack() to check the MEMLOCK limit.  It will
never be asked to wire the stack.  Moreover, it doesn't even implement
wiring of the stack.

Reviewed by:	kib, markj
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D11421
This commit is contained in:
Alan Cox 2017-06-30 15:49:36 +00:00
parent 2da3e34e0a
commit 8056df6e25
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=320498
2 changed files with 10 additions and 8 deletions
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4
sys/kern/kern_exec.c
View File

@ -1091,6 +1091,10 @@ exec_new_vmspace(struct image_params *imgp, struct sysentvec *sv)
shmexit(vmspace);
pmap_remove_pages(vmspace_pmap(vmspace));
vm_map_remove(map, vm_map_min(map), vm_map_max(map));
/* An exec terminates mlockall(MCL_FUTURE). */
vm_map_lock(map);
vm_map_modflags(map, 0, MAP_WIREFUTURE);
vm_map_unlock(map);
} else {
error = vmspace_exec(p, sv_minuser, sv->sv_maxuser);
if (error)

14
sys/vm/vm_map.c
View File

@ -3557,25 +3557,23 @@ vmspace_fork(struct vmspace *vm1, vm_ooffset_t *fork_charge)
return (vm2);
}
/*
* Create a process's stack for exec_new_vmspace(). This function is never
* asked to wire the newly created stack.
*/
int
vm_map_stack(vm_map_t map, vm_offset_t addrbos, vm_size_t max_ssize,
vm_prot_t prot, vm_prot_t max, int cow)
{
vm_size_t growsize, init_ssize;
rlim_t lmemlim, vmemlim;
rlim_t vmemlim;
int rv;
MPASS((map->flags & MAP_WIREFUTURE) == 0);
growsize = sgrowsiz;
init_ssize = (max_ssize < growsize) ? max_ssize : growsize;
vm_map_lock(map);
lmemlim = lim_cur(curthread, RLIMIT_MEMLOCK);
vmemlim = lim_cur(curthread, RLIMIT_VMEM);
if (!old_mlock && map->flags & MAP_WIREFUTURE) {
if (ptoa(pmap_wired_count(map->pmap)) + init_ssize > lmemlim) {
rv = KERN_NO_SPACE;
goto out;
}
}
/* If we would blow our VMEM resource limit, no go */
if (map->size + init_ssize > vmemlim) {
rv = KERN_NO_SPACE;