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Revert back to use int for the page counts. In vn_io_fault(), the i/o

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is chunked to pieces limited by integer io_hold_cnt tunable, while
vm_fault_quick_hold_pages() takes integer max_count as the upper bound.

Rearrange the checks to correctly handle overflowing address arithmetic.

Submitted by:	bde
Tested by:	pho
Discussed with:	alc
MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2013-11-20 08:45:26 +00:00
parent a2c0f474c4
commit 7e14088d93
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=258365
2 changed files with 13 additions and 15 deletions
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20
sys/kern/vfs_vnops.c
View File

@ -933,9 +933,8 @@ vn_io_fault(struct file *fp, struct uio *uio, struct ucred *active_cred,
void *rl_cookie;
struct mount *mp;
vm_page_t *prev_td_ma;
int error, save, saveheld, prev_td_ma_cnt;
int error, cnt, save, saveheld, prev_td_ma_cnt;
vm_offset_t addr, end;
vm_size_t cnt;
vm_prot_t prot;
size_t len, resid;
ssize_t adv;
@ -1008,21 +1007,20 @@ vn_io_fault(struct file *fp, struct uio *uio, struct ucred *active_cred,
uio_clone->uio_iovcnt--;
continue;
}
addr = (vm_offset_t)uio_clone->uio_iov->iov_base;
if (len > io_hold_cnt * PAGE_SIZE)
len = io_hold_cnt * PAGE_SIZE;
addr = (uintptr_t)uio_clone->uio_iov->iov_base;
end = round_page(addr + len);
cnt = howmany(end - trunc_page(addr), PAGE_SIZE);
if (end < addr) {
error = EFAULT;
break;
}
cnt = atop(end - trunc_page(addr));
/*
* A perfectly misaligned address and length could cause
* both the start and the end of the chunk to use partial
* page. +2 accounts for such a situation.
*/
if (cnt > io_hold_cnt + 2) {
len = io_hold_cnt * PAGE_SIZE;
KASSERT(howmany(round_page(addr + len) -
trunc_page(addr), PAGE_SIZE) <= io_hold_cnt + 2,
("cnt overflow"));
}
cnt = vm_fault_quick_hold_pages(&td->td_proc->p_vmspace->vm_map,
addr, len, prot, ma, io_hold_cnt + 2);
if (cnt == -1) {

8
sys/vm/vm_fault.c
View File

@ -1074,12 +1074,12 @@ vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len,
{
vm_offset_t end, va;
vm_page_t *mp;
vm_size_t count;
int count;
boolean_t pmap_failed;
if (len == 0)
return (0);
end = round_page(addr + len);
end = round_page(addr + len);
addr = trunc_page(addr);
/*
@ -1088,9 +1088,9 @@ vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len,
if (addr < vm_map_min(map) || addr > end || end > vm_map_max(map))
return (-1);
count = howmany(end - addr, PAGE_SIZE);
if (count > max_count)
if (atop(end - addr) > max_count)
panic("vm_fault_quick_hold_pages: count > max_count");
count = atop(end - addr);
/*
* Most likely, the physical pages are resident in the pmap, so it is