diff options
| author |   tedu <tedu@openbsd.org> | 2015-09-26 15:37:28 +0000 |
|---|---|---|
| committer | tedu <tedu@openbsd.org> | 2015-09-26 15:37:28 +0000 |
| commit | 39b0071161235cf072a988f78d81fb4d7654a4eb (patch) | |
| tree | 1990a73fce12980231885f4753799ef0d6cb0a8b /sys | |
| parent | We don't need no stinking "EXAMPLE OF THE DSA" or README (the credits are (diff) | |
| download | wireguard-openbsd-39b0071161235cf072a988f78d81fb4d7654a4eb.tar.xz wireguard-openbsd-39b0071161235cf072a988f78d81fb4d7654a4eb.zip | |
matthew noticed there's a race where we are using the kernel lock to tie
together the unmap and map portions of a fixed mmap. make this explicit
by pulling the lock up higher. in preparation for unlocking the syscall.
there's still (always has been) a race where if the unmap sleeps, another
mmap may see partial results because the map lock isn't held througout.
another problem, another day.
Diffstat (limited to 'sys')
| -rw-r--r-- | sys/uvm/uvm_mmap.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/sys/uvm/uvm_mmap.c b/sys/uvm/uvm_mmap.c index c473046c7f4..92498a4e397 100644 --- a/sys/uvm/uvm_mmap.c +++ b/sys/uvm/uvm_mmap.c @@ -1,4 +1,4 @@ -/* $OpenBSD: uvm_mmap.c,v 1.115 2015/09/23 00:16:44 guenther Exp $ */ +/* $OpenBSD: uvm_mmap.c,v 1.116 2015/09/26 15:37:28 tedu Exp $ */ /* $NetBSD: uvm_mmap.c,v 1.49 2001/02/18 21:19:08 chs Exp $ */ /* @@ -513,8 +513,12 @@ is_anon: /* label for SunOS style /dev/zero */ } } maxprot = PROT_MASK; + if ((flags & (MAP_FIXED|__MAP_NOREPLACE)) == MAP_FIXED) + KERNEL_LOCK(); error = uvm_mmapanon(&p->p_vmspace->vm_map, &addr, size, prot, maxprot, flags, p->p_rlimit[RLIMIT_MEMLOCK].rlim_cur, p); + if ((flags & (MAP_FIXED|__MAP_NOREPLACE)) == MAP_FIXED) + KERNEL_UNLOCK(); } if (error == 0) @@ -987,9 +991,8 @@ uvm_mmapanon(vm_map_t map, vaddr_t *addr, vsize_t size, vm_prot_t prot, uvmflag |= UVM_FLAG_FIXED; if ((flags & __MAP_NOREPLACE) == 0) { - KERNEL_LOCK(); + /* KERNEL_LOCK held above */ uvm_unmap(map, *addr, *addr + size); /* zap! */ - KERNEL_UNLOCK(); } } |