5.4-stable patches

added patches:
	x86-mm-avoid-using-set_pgd-outside-of-real-pgd-pages.patch

diff --git a/queue-5.4/series b/queue-5.4/series
index d46b27cd867c07344357f9b6214d3788103f2c58..6643acd92737773523fc7bab3b1d0846ded569b8 100644 (file)
--- a/queue-5.4/series
+++ b/queue-5.4/series
@@ -21,3 +21,4 @@ cifs-get-rid-of-kstrdup_const-d-paths.patch
 cifs-introduce-helpers-for-finding-tcp-connection.patch
 cifs-merge-is_path_valid-into-get_normalized_path.patch
 cifs-fix-potential-deadlock-when-updating-vol-in-cifs_reconnect.patch
+x86-mm-avoid-using-set_pgd-outside-of-real-pgd-pages.patch

diff --git a/queue-5.4/x86-mm-avoid-using-set_pgd-outside-of-real-pgd-pages.patch b/queue-5.4/x86-mm-avoid-using-set_pgd-outside-of-real-pgd-pages.patch
new file mode 100644 (file)
index 0000000..36b6e0b
--- /dev/null
+++ b/queue-5.4/x86-mm-avoid-using-set_pgd-outside-of-real-pgd-pages.patch
@@ -0,0 +1,58 @@
+From d082d48737c75d2b3cc1f972b8c8674c25131534 Mon Sep 17 00:00:00 2001
+From: Lee Jones <lee@kernel.org>
+Date: Wed, 14 Jun 2023 17:38:54 +0100
+Subject: x86/mm: Avoid using set_pgd() outside of real PGD pages
+
+From: Lee Jones <lee@kernel.org>
+
+commit d082d48737c75d2b3cc1f972b8c8674c25131534 upstream.
+
+KPTI keeps around two PGDs: one for userspace and another for the
+kernel. Among other things, set_pgd() contains infrastructure to
+ensure that updates to the kernel PGD are reflected in the user PGD
+as well.
+
+One side-effect of this is that set_pgd() expects to be passed whole
+pages.  Unfortunately, init_trampoline_kaslr() passes in a single entry:
+'trampoline_pgd_entry'.
+
+When KPTI is on, set_pgd() will update 'trampoline_pgd_entry' (an
+8-Byte globally stored [.bss] variable) and will then proceed to
+replicate that value into the non-existent neighboring user page
+(located +4k away), leading to the corruption of other global [.bss]
+stored variables.
+
+Fix it by directly assigning 'trampoline_pgd_entry' and avoiding
+set_pgd().
+
+[ dhansen: tweak subject and changelog ]
+
+Fixes: 0925dda5962e ("x86/mm/KASLR: Use only one PUD entry for real mode trampoline")
+Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
+Signed-off-by: Lee Jones <lee@kernel.org>
+Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
+Cc: <stable@vger.kernel.org>
+Link: https://lore.kernel.org/all/20230614163859.924309-1-lee@kernel.org/g
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ arch/x86/mm/kaslr.c |    8 ++++----
+ 1 file changed, 4 insertions(+), 4 deletions(-)
+
+--- a/arch/x86/mm/kaslr.c
++++ b/arch/x86/mm/kaslr.c
+@@ -182,11 +182,11 @@ static void __meminit init_trampoline_pu
+               set_p4d(p4d_tramp,
+                       __p4d(_KERNPG_TABLE | __pa(pud_page_tramp)));
+ 
+-              set_pgd(&trampoline_pgd_entry,
+-                      __pgd(_KERNPG_TABLE | __pa(p4d_page_tramp)));
++              trampoline_pgd_entry =
++                      __pgd(_KERNPG_TABLE | __pa(p4d_page_tramp));
+       } else {
+-              set_pgd(&trampoline_pgd_entry,
+-                      __pgd(_KERNPG_TABLE | __pa(pud_page_tramp)));
++              trampoline_pgd_entry =
++                      __pgd(_KERNPG_TABLE | __pa(pud_page_tramp));
+       }
+ }
+