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bhyve: Use MAP_GUARD when mapping guest memory ranges.

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Instead of relying on PROT_NONE mappings with MAP_ANON, use MAP_GUARD
to reserve address space around guest memory ranges including the
guard ranges of address space around mappings.

Submitted by:	Shawn Webb
Reviewed by:	araujo
Approved by:	re (rgrimes)
MFC after:	1 month
Sponsored by:	HardendBSD and G2, Inc
Differential Revision:	https://reviews.freebsd.org/D16822
This commit is contained in:
John Baldwin 2018-09-06 20:29:40 +00:00
parent c56c7299c2
commit 6a9648b537
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=338511
1 changed files with 4 additions and 5 deletions
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9
lib/libvmmapi/vmmapi.c
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@ -362,7 +362,7 @@ vm_setup_memory(struct vmctx *ctx, size_t memsize, enum vm_mmap_style vms)
size_t objsize, len;
vm_paddr_t gpa;
char *baseaddr, *ptr;
int error, flags;
int error;
assert(vms == VM_MMAP_ALL);
@ -389,8 +389,7 @@ vm_setup_memory(struct vmctx *ctx, size_t memsize, enum vm_mmap_style vms)
* and the adjoining guard regions.
*/
len = VM_MMAP_GUARD_SIZE + objsize + VM_MMAP_GUARD_SIZE;
flags = MAP_PRIVATE | MAP_ANON | MAP_NOCORE | MAP_ALIGNED_SUPER;
ptr = mmap(NULL, len, PROT_NONE, flags, -1, 0);
ptr = mmap(NULL, len, PROT_NONE, MAP_GUARD | MAP_ALIGNED_SUPER, -1, 0);
if (ptr == MAP_FAILED)
return (-1);
@ -492,8 +491,8 @@ vm_create_devmem(struct vmctx *ctx, int segid, const char *name, size_t len)
* adjoining guard regions.
*/
len2 = VM_MMAP_GUARD_SIZE + len + VM_MMAP_GUARD_SIZE;
flags = MAP_PRIVATE | MAP_ANON | MAP_NOCORE | MAP_ALIGNED_SUPER;
base = mmap(NULL, len2, PROT_NONE, flags, -1, 0);
base = mmap(NULL, len2, PROT_NONE, MAP_GUARD | MAP_ALIGNED_SUPER, -1,
0);
if (base == MAP_FAILED)
goto done;