Re: [PATCH] linux-user: Ensure mmap_min_addr is non-zero

[Laurent Vivier]

Le 24/07/2020 à 23:23, Richard Henderson a écrit :
> When the chroot does not have /proc mounted, we can read neither
> /proc/sys/vm/mmap_min_addr nor /proc/sys/maps.
> 
> The enforcement of mmap_min_addr in the host kernel is done by
> the security module, and so does not apply to processes owned
> by root.  Which leads pgd_find_hole_fallback to succeed in probing
> a reservation at address 0.  Which confuses pgb_reserved_va to
> believe that guest_base has not actually been initialized.
> 
> We don't actually want NULL addresses to become accessible, so
> make sure that mmap_min_addr is initialized with a non-zero value.
> 
> Buglink: https://bugs.launchpad.net/qemu/+bug/1888728
> Reported-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  linux-user/main.c | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
> 

Richard, do you want to add this fix in one of your branches PR?

In this case:
Acked-by: Laurent Vivier <laurent@vivier.eu>

Otherwise I can prepare a small one for linux-user, adding one or two
fixes...

Thanks,
Laurent