Re: git: 50d663b14b31 - main - vm: Fix vm_map_find_min()

On Wed, Jul 26, 2023 at 05:25:37AM +0000, Alan Cox wrote:
> The branch main has been updated by alc:
> 
> URL: https://cgit.FreeBSD.org/src/commit/?id=50d663b14b310d6020b4b6cc92d4fae985f086f2
> 
> commit 50d663b14b310d6020b4b6cc92d4fae985f086f2
> Author:     Alan Cox <alc@FreeBSD.org>
> AuthorDate: 2023-07-25 07:24:19 +0000
> Commit:     Alan Cox <alc@FreeBSD.org>
> CommitDate: 2023-07-26 05:24:50 +0000
> 
>     vm: Fix vm_map_find_min()
>     
>     Fix the handling of address hints that are less than min_addr by
>     vm_map_find_min().
>     
Thank you for fixing that, however it still fails under Linuxulator.


#include <sys/mman.h>
#include <sys/stat.h>

#include <assert.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

int
main(int argc, char** argv)
{
	struct stat sb;
	void *s32;
	int f, r;

	f = open(argv[0], O_RDONLY);
	assert(f > 0);

	r = fstat(f, &sb);
	assert(r == 0);

	s32  = mmap(NULL, sb.st_size, PROT_READ,
	    MAP_32BIT|MAP_PRIVATE, f, 0);
	assert(s32 != MAP_FAILED);
	assert((uintptr_t)s32 < 0x80000000);

	close(f);
	munmap(s32, sb.st_size);
	return (0);
}



>     Reported by:    dchagin
>     Reviewed by:    kib
>     Fixes:  d8e6f4946cec0 "vm: Fix anonymous memory clustering under ASLR"
>     Differential Revision:  https://reviews.freebsd.org/D41159
> ---
>  sys/vm/vm_map.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c
> index 444e09986d4e..eb607d519247 100644
> --- a/sys/vm/vm_map.c
> +++ b/sys/vm/vm_map.c
> @@ -2255,10 +2255,10 @@ vm_map_find_min(vm_map_t map, vm_object_t object, vm_ooffset_t offset,
>  	int rv;
>  
>  	hint = *addr;
> -	if (hint == 0)
> +	if (hint == 0) {
>  		cow |= MAP_NO_HINT;
> -	if (hint < min_addr)
>  		*addr = hint = min_addr;
> +	}
>  	for (;;) {
>  		rv = vm_map_find(map, object, offset, addr, length, max_addr,
>  		    find_space, prot, max, cow);