* Eric Paris ([email protected]) wrote:
> +mmap_protect_memory
I'm terrible at names, but something like mmap_minimum_addr would be a
little clearer at describing that it's a lower bound on mapping memory.
BTW, this is also an arch specific issue, those with disjoint kernel
and user memory space don't suffer (yet another reason to default to 0).
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -615,6 +615,15 @@ static ctl_table kern_table[] = {
> .proc_handler = &proc_dointvec,
> },
> #endif
> + {
> + .ctl_name = CTL_UNNUMBERED,
> + .procname = "mmap_protect_memory",
> + .data = &mmap_protect_memory,
> + .maxlen = sizeof(int),
> + .mode = 0644,
> + .proc_handler = &proc_dointvec,
> + .strategy = &sysctl_intvec,
I don't think this strategy does anything without some boundary values.
> --- a/mm/mremap.c
> +++ b/mm/mremap.c
> @@ -291,6 +291,10 @@ unsigned long do_mremap(unsigned long addr,
> if ((addr <= new_addr) && (addr+old_len) > new_addr)
> goto out;
>
> + ret = security_file_mmap(0, 0, 0, 0, new_addr, 1);
> + if (ret)
> + goto out;
> +
> ret = do_munmap(mm, new_addr, new_len);
> if (ret)
> goto out;
> @@ -390,9 +394,16 @@ unsigned long do_mremap(unsigned long addr,
>
> new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
> vma->vm_pgoff, map_flags);
> - ret = new_addr;
> - if (new_addr & ~PAGE_MASK)
> + if (new_addr & ~PAGE_MASK) {
> + ret = new_addr;
> goto out;
> + }
> +
> + ret = security_file_mmap(0, 0, 0, 0, new_addr, 1);
> + if (ret)
> + goto out;
> +
> + ret = new_addr;
Nit: unnecessary assignment...
> }
> ret = move_vma(vma, addr, old_len, new_len, new_addr);
^^^
...as it's overwritten immediately after.
-
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