Patch "arm64: set UXN on swapper page tables" has been added to the 5.19-stable tree

[gregkh at linuxfoundation.org]

This is a note to let you know that I've just added the patch titled

    arm64: set UXN on swapper page tables

to the 5.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     arm64-set-uxn-on-swapper-page-tables.patch
and it can be found in the queue-5.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable at vger.kernel.org> know about it.


>From will at kernel.org  Mon Aug  8 15:23:59 2022
From: Will Deacon <will at kernel.org>
Date: Mon,  8 Aug 2022 13:53:21 +0100
Subject: arm64: set UXN on swapper page tables
To: gregkh at linuxfoundation.org
Cc: linux-kernel at vger.kernel.org, linux-arm-kernel at lists.infradead.org, Peter Collingbourne <pcc at google.com>, stable at vger.kernel.org, Will Deacon <will at kernel.org>, Ard Biesheuvel <ardb at kernel.org>, Catalin Marinas <catalin.marinas at arm.com>
Message-ID: <20220808125321.32598-1-will at kernel.org>

From: Peter Collingbourne <pcc at google.com>

[ This issue was fixed upstream by accident in c3cee924bd85 ("arm64:
  head: cover entire kernel image in initial ID map") as part of a
  large refactoring of the arm64 boot flow. This simple fix is therefore
  preferred for -stable backporting ]

On a system that implements FEAT_EPAN, read/write access to the idmap
is denied because UXN is not set on the swapper PTEs. As a result,
idmap_kpti_install_ng_mappings panics the kernel when accessing
__idmap_kpti_flag. Fix it by setting UXN on these PTEs.

Fixes: 18107f8a2df6 ("arm64: Support execute-only permissions with Enhanced PAN")
Cc: <stable at vger.kernel.org> # 5.15
Link: https://linux-review.googlesource.com/id/Ic452fa4b4f74753e54f71e61027e7222a0fae1b1
Signed-off-by: Peter Collingbourne <pcc at google.com>
Acked-by: Will Deacon <will at kernel.org>
Cc: Ard Biesheuvel <ardb at kernel.org>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Link: https://lore.kernel.org/r/20220719234909.1398992-1-pcc@google.com
Signed-off-by: Will Deacon <will at kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 arch/arm64/include/asm/kernel-pgtable.h |    4 ++--
 arch/arm64/kernel/head.S                |    2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

--- a/arch/arm64/include/asm/kernel-pgtable.h
+++ b/arch/arm64/include/asm/kernel-pgtable.h
@@ -103,8 +103,8 @@
 /*
  * Initial memory map attributes.
  */
-#define SWAPPER_PTE_FLAGS	(PTE_TYPE_PAGE | PTE_AF | PTE_SHARED)
-#define SWAPPER_PMD_FLAGS	(PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S)
+#define SWAPPER_PTE_FLAGS	(PTE_TYPE_PAGE | PTE_AF | PTE_SHARED | PTE_UXN)
+#define SWAPPER_PMD_FLAGS	(PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S | PMD_SECT_UXN)
 
 #if ARM64_KERNEL_USES_PMD_MAPS
 #define SWAPPER_MM_MMUFLAGS	(PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS)
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -285,7 +285,7 @@ SYM_FUNC_START_LOCAL(__create_page_table
 	subs	x1, x1, #64
 	b.ne	1b
 
-	mov	x7, SWAPPER_MM_MMUFLAGS
+	mov_q	x7, SWAPPER_MM_MMUFLAGS
 
 	/*
 	 * Create the identity mapping.


Patches currently in stable-queue which might be from will at kernel.org are

queue-5.19/arm64-set-uxn-on-swapper-page-tables.patch
queue-5.19/crypto-arm64-poly1305-fix-a-read-out-of-bound.patch