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Fix a use-after-free in the riscv pmap_release() implementation.

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Don't bother zeroing the top-level page before freeing it.  Previously,
the page was freed before being zeroed.

Reviewed by:	jhb, kib
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D18720
This commit is contained in:
Mark Johnston 2019-01-03 16:26:52 +00:00
parent bad66a29d4
commit 7c59ec14e6
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=342736
1 changed files with 3 additions and 7 deletions
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10
sys/riscv/riscv/pmap.c
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@ -1297,17 +1297,13 @@ pmap_release(pmap_t pmap)
("pmap_release: pmap resident count %ld != 0",
pmap->pm_stats.resident_count));
m = PHYS_TO_VM_PAGE(DMAP_TO_PHYS((vm_offset_t)pmap->pm_l1));
vm_page_unwire_noq(m);
vm_page_free_zero(m);
/* Remove pmap from the allpmaps list */
mtx_lock(&allpmaps_lock);
LIST_REMOVE(pmap, pm_list);
mtx_unlock(&allpmaps_lock);
/* Remove kernel pagetables */
bzero(pmap->pm_l1, PAGE_SIZE);
m = PHYS_TO_VM_PAGE(DMAP_TO_PHYS((vm_offset_t)pmap->pm_l1));
vm_page_unwire_noq(m);
vm_page_free(m);
}
#if 0