Re: [PATCH v2] linux-user/mmap: Return EFAULT/EINVAL for invalid addresses

[Laurent Vivier <laurent@vivier.eu>]

Le 16/02/2021 à 20:01, Richard Purdie a écrit :
> When using qemu-i386 to build qemux86 webkitgtk on musl, it sits in an
> infinite loop of mremap calls of ever decreasing/increasing addresses.
> 
> I suspect something in the musl memory allocation code loops
> indefinitely if it only sees ENOMEM and only exits when it hits other
> errors such as EFAULT or EINVAL.
> 
> According to the docs, trying to mremap outside the address space
> can/should return EFAULT and changing this allows the build to succeed.
> 
> A better return value for the other cases of invalid addresses is
> EINVAL rather than ENOMEM so adjust the other part of the test to this.
> 
> Signed-off-by: Richard Purdie <richard.purdie@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
> @@ -722,12 +722,14 @@ abi_long target_mremap(abi_ulong old_add
>      int prot;
>      void *host_addr;
>  
> -    if (!guest_range_valid(old_addr, old_size) ||
> -        ((flags & MREMAP_FIXED) &&
> -         !guest_range_valid(new_addr, new_size)) ||
> -        ((flags & MREMAP_MAYMOVE) == 0 &&
> -         !guest_range_valid(old_addr, new_size))) {
> -        errno = ENOMEM;
> +    if (!guest_range_valid(old_addr, old_size)) {
> +        errno = EFAULT;
> +        return -1;
> +    }
> +
> +    if (((flags & MREMAP_FIXED) && !guest_range_valid(new_addr, new_size)) ||
> +        ((flags & MREMAP_MAYMOVE) == 0 && !guest_range_valid(old_addr, new_size))) {
> +        errno = EINVAL;
>          return -1;
>      }
>  
> 
> 

Reviewed-by: Laurent Vivier <laurent@vivier.eu>