Currently the vdso doesn't include .note.gnu.property or a GNU noexec
stack annotation (the -z noexecstack in the linker script is
ineffective because we specify PHDRs explicitly.)
The motivation is that the dynamic linker currently do not check
these.
However, this is a weak excuse: the vdso*.so are also supposed to be
usable at link libraries, and there is no reason why the dynamic
linker might not want or need to check these in the future, so add
them back in -- it is trivial enough.
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
---
arch/x86/entry/vdso/common/vdso-layout.lds.S | 51 +++++++++++---------
1 file changed, 28 insertions(+), 23 deletions(-)
diff --git a/arch/x86/entry/vdso/common/vdso-layout.lds.S b/arch/x86/entry/vdso/common/vdso-layout.lds.S
index ec1ac191a057..696bacb99ed8 100644
--- a/arch/x86/entry/vdso/common/vdso-layout.lds.S
+++ b/arch/x86/entry/vdso/common/vdso-layout.lds.S
@@ -26,7 +26,7 @@ SECTIONS
. = SIZEOF_HEADERS;
- .hash : { *(.hash) } :text
+ .hash : { *(.hash) } :text
.gnu.hash : { *(.gnu.hash) }
.dynsym : { *(.dynsym) }
.dynstr : { *(.dynstr) }
@@ -34,7 +34,7 @@ SECTIONS
.gnu.version_d : { *(.gnu.version_d) }
.gnu.version_r : { *(.gnu.version_r) }
- .dynamic : { *(.dynamic) } :text :dynamic
+ .dynamic : { *(.dynamic) } :text :dynamic
.rodata : {
*(.rodata*)
@@ -45,31 +45,28 @@ SECTIONS
*(.bss*)
*(.dynbss*)
*(.gnu.linkonce.b.*)
- } :text
+ } :text
- /*
- * Discard .note.gnu.property sections which are unused and have
- * different alignment requirement from vDSO note sections.
- */
- /DISCARD/ : {
+ .note.gnu.property : {
*(.note.gnu.property)
- }
- .note : { *(.note.*) } :text :note
-
- .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
- .eh_frame : { KEEP (*(.eh_frame)) } :text
+ } :text :note :gnu_property
+ .note : {
+ *(.note*)
+ } :text :note
+ .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
+ .eh_frame : {
+ KEEP (*(.eh_frame))
+ *(.eh_frame.*)
+ } :text
/*
* Text is well-separated from actual data: there's plenty of
* stuff that isn't used at runtime in between.
- */
-
+ */
.text : {
*(.text*)
- } :text =0x90909090,
-
-
+ } :text =0x90909090
.altinstructions : { *(.altinstructions) } :text
.altinstr_replacement : { *(.altinstr_replacement) } :text
@@ -87,15 +84,23 @@ SECTIONS
* Very old versions of ld do not recognize this name token; use the constant.
*/
#define PT_GNU_EH_FRAME 0x6474e550
+#define PT_GNU_STACK 0x6474e551
+#define PT_GNU_PROPERTY 0x6474e553
/*
* We must supply the ELF program headers explicitly to get just one
* PT_LOAD segment, and set the flags explicitly to make segments read-only.
- */
+*/
+#define PF_R FLAGS(4)
+#define PF_RW FLAGS(6)
+#define PF_RX FLAGS(5)
+
PHDRS
{
- text PT_LOAD FLAGS(5) FILEHDR PHDRS; /* PF_R|PF_X */
- dynamic PT_DYNAMIC FLAGS(4); /* PF_R */
- note PT_NOTE FLAGS(4); /* PF_R */
- eh_frame_hdr PT_GNU_EH_FRAME;
+ text PT_LOAD PF_RX FILEHDR PHDRS;
+ dynamic PT_DYNAMIC PF_R;
+ note PT_NOTE PF_R;
+ eh_frame_hdr PT_GNU_EH_FRAME PF_R;
+ gnu_stack PT_GNU_STACK PF_RW;
+ gnu_property PT_GNU_PROPERTY PF_R;
}
--
2.51.1On 12/11/2025 8:22 pm, H. Peter Anvin wrote:
> arch/x86/entry/vdso/common/vdso-layout.lds.S | 51 +++++++++++---------
> 1 file changed, 28 insertions(+), 23 deletions(-)
>
> diff --git a/arch/x86/entry/vdso/common/vdso-layout.lds.S b/arch/x86/entry/vdso/common/vdso-layout.lds.S
> index ec1ac191a057..696bacb99ed8 100644
> --- a/arch/x86/entry/vdso/common/vdso-layout.lds.S
> +++ b/arch/x86/entry/vdso/common/vdso-layout.lds.S
> @@ -26,7 +26,7 @@ SECTIONS
>
> . = SIZEOF_HEADERS;
>
> - .hash : { *(.hash) } :text
> + .hash : { *(.hash) } :text
> .gnu.hash : { *(.gnu.hash) }
> .dynsym : { *(.dynsym) }
> .dynstr : { *(.dynstr) }
> @@ -34,7 +34,7 @@ SECTIONS
> .gnu.version_d : { *(.gnu.version_d) }
> .gnu.version_r : { *(.gnu.version_r) }
>
> - .dynamic : { *(.dynamic) } :text :dynamic
> + .dynamic : { *(.dynamic) } :text :dynamic
>
> .rodata : {
> *(.rodata*)
> @@ -45,31 +45,28 @@ SECTIONS
> *(.bss*)
> *(.dynbss*)
> *(.gnu.linkonce.b.*)
> - } :text
> + } :text
>
> - /*
> - * Discard .note.gnu.property sections which are unused and have
> - * different alignment requirement from vDSO note sections.
> - */
> - /DISCARD/ : {
> + .note.gnu.property : {
> *(.note.gnu.property)
> - }
> - .note : { *(.note.*) } :text :note
> -
> - .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
> - .eh_frame : { KEEP (*(.eh_frame)) } :text
> + } :text :note :gnu_property
> + .note : {
> + *(.note*)
> + } :text :note
>
> + .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
> + .eh_frame : {
> + KEEP (*(.eh_frame))
> + *(.eh_frame.*)
> + } :text
>
> /*
> * Text is well-separated from actual data: there's plenty of
> * stuff that isn't used at runtime in between.
> - */
> -
> + */
> .text : {
> *(.text*)
> - } :text =0x90909090,
> -
> -
> + } :text =0x90909090
>
Almost all of these hunks look to be whitespace changes only. Was that
intentional? It certainly makes it harder to read.
> .altinstructions : { *(.altinstructions) } :text
> .altinstr_replacement : { *(.altinstr_replacement) } :text
> @@ -87,15 +84,23 @@ SECTIONS
> * Very old versions of ld do not recognize this name token; use the constant.
> */
> #define PT_GNU_EH_FRAME 0x6474e550
> +#define PT_GNU_STACK 0x6474e551
> +#define PT_GNU_PROPERTY 0x6474e553
>
> /*
> * We must supply the ELF program headers explicitly to get just one
> * PT_LOAD segment, and set the flags explicitly to make segments read-only.
> - */
> +*/
This looks like it wants undoing too.
That said, I do strongly agree with the reasoning behind this patch.
~Andrew
On 2025-11-13 11:09, Andrew Cooper wrote:
>
> Almost all of these hunks look to be whitespace changes only. Was that
> intentional? It certainly makes it harder to read.
>
It is intentional; although it adds to the patch it tidies up the file itself.
>> .altinstructions : { *(.altinstructions) } :text
>> .altinstr_replacement : { *(.altinstr_replacement) } :text
>> @@ -87,15 +84,23 @@ SECTIONS
>> * Very old versions of ld do not recognize this name token; use the constant.
>> */
>> #define PT_GNU_EH_FRAME 0x6474e550
>> +#define PT_GNU_STACK 0x6474e551
>> +#define PT_GNU_PROPERTY 0x6474e553
>>
>> /*
>> * We must supply the ELF program headers explicitly to get just one
>> * PT_LOAD segment, and set the flags explicitly to make segments read-only.
>> - */
>> +*/
>
> This looks like it wants undoing too.
OK, fair.
> That said, I do strongly agree with the reasoning behind this patch.
Thanks.
-hpa
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