Commit-ID: bab2c42e8a52d5a76009ad805c97060377f98fdf Gitweb: http://git.kernel.org/tip/bab2c42e8a52d5a76009ad805c97060377f98fdf Author: Andy Lutomirski <l...@amacapital.net> AuthorDate: Mon, 3 Mar 2014 22:12:23 +0100 Committer: H. Peter Anvin <h...@linux.intel.com> CommitDate: Wed, 5 Mar 2014 14:02:39 -0800
x86, vdso: Zero-pad the VVAR page By coincidence, the VVAR page is at the end of an ELF segment. As a result, if it ends up being a partial page, the kernel loader will leave garbage behind at the end of the vvar page. Zero-pad it to a full page to fix this issue. This has probably been broken since the VVAR page was introduced. On QEMU, if you dump the run-time contents of the VVAR page, you can find entertaining strings from seabios left behind. It's remotely possible that this is a security bug -- conceivably there's some BIOS out there that leaves something sensitive in the few K of memory that is exposed to userspace. Signed-off-by: Stefani Seibold <stef...@seibold.net> Link: http://lkml.kernel.org/r/1393881143-3569-13-git-send-email-stef...@seibold.net Signed-off-by: H. Peter Anvin <h...@linux.intel.com> --- arch/x86/kernel/vmlinux.lds.S | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index 1d4897b..49edf2d 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -164,6 +164,11 @@ SECTIONS #undef __VVAR_KERNEL_LDS #undef EMIT_VVAR + /* + * Pad the rest of the page with zeros. Otherwise the loader + * can leave garbage here. + */ + . = __vvar_beginning_hack + PAGE_SIZE; } :data . = ALIGN(__vvar_page + PAGE_SIZE, PAGE_SIZE); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
