On Fri, 2021-01-08 at 17:42 +0000, Richard Purdie wrote:
> If mremap() is called without the MREMAP_MAYMOVE flag with a start address
> just before the end of memory (reserved_va) where new_size would exceed
> it (and GUEST_ADDR_MAX), the assert(end - 1 <= GUEST_ADDR_MAX) in
> page_set_flags() would trigger.
>
> Add an extra guard to the guest_range_valid() checks to prevent this and
> avoid asserting binaries when reserved_va is set.
>
> This meant a bug I was seeing locally now gives the same behaviour
> regardless of whether reserved_va is set or not.
>
> Signed-off-by: Richard Purdie <richard.pur...@linuxfoundation.org
>
> Index: qemu-5.2.0/linux-user/mmap.c
> ===================================================================
> --- qemu-5.2.0.orig/linux-user/mmap.c
> +++ qemu-5.2.0/linux-user/mmap.c
> @@ -727,7 +727,9 @@ abi_long target_mremap(abi_ulong old_add
>
>
> if (!guest_range_valid(old_addr, old_size) ||
> ((flags & MREMAP_FIXED) &&
> - !guest_range_valid(new_addr, new_size))) {
> + !guest_range_valid(new_addr, new_size)) ||
> + ((flags & MREMAP_MAYMOVE) == 0 &&
> + !guest_range_valid(old_addr, new_size))) {
> errno = ENOMEM;
> return -1;
> }
>
>
Any comments on this? I believe its a valid issue that needs fixing and
multiple distros appear to be carrying fixes in this area related to
this.
Cheers,
Richard
