Re: [PATCH 3/3 V13] RO/NX protection for loadable kernel

[matthieu castet]

Kees Cook a écrit :
> Hi,
>
> I was just shown this[1] on Xen from an Ubuntu bug report[2].
>
> [    1.230382] NX-protecting the kernel data: 3884k
> [    1.231002] BUG: unable to handle kernel paging request at c1782ae0
> ...
> [    1.231145] Call Trace:
> [    1.231152]  [<c0138481>] ? __change_page_attr+0x2c1/0x370
> [    1.231161]  [<c02163a1>] ? __purge_vmap_area_lazy+0xc1/0x180
> [    1.231169]  [<c013857c>] ? __change_page_attr_set_clr+0x4c/0xb0
> [    1.231176]  [<c0138838>] ? change_page_attr_set_clr+0x128/0x300
> [    1.231183]  [<c010798e>] ? __raw_callee_save_xen_restore_fl+0x6/0x8
> [    1.231192]  [<c0159ca1>] ? vprintk+0x171/0x3f0
> [    1.231198]  [<c0138bdf>] ? set_memory_nx+0x5f/0x70
>
>
> Does Xen have different size page table allocations or something weird?
Note that this one isn't related to this one but to "Add NX protection for kernel data".

But have no idea how xen page table work.

Matthieu
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