6.8-stable patches

added patches:
	x86-efistub-call-mixed-mode-boot-services-on-the-firmware-s-stack.patch

diff --git a/queue-6.8/series b/queue-6.8/series
index a22edbd07af5d95f510ac71903a0e8db756928c8..80056d7226d0d474570b05f9b98c07b708cc8e0d 100644 (file)
--- a/queue-6.8/series
+++ b/queue-6.8/series
@@ -243,3 +243,4 @@ workqueue-shorten-events_freezable_power_efficient-name.patch
 drm-amd-display-use-freesync-when-drm_edid_feature_continuous_freq-found.patch
 netfilter-nf_tables-reject-constant-set-with-timeout.patch
 revert-crypto-pkcs7-remove-sha1-support.patch
+x86-efistub-call-mixed-mode-boot-services-on-the-firmware-s-stack.patch

diff --git a/queue-6.8/x86-efistub-call-mixed-mode-boot-services-on-the-firmware-s-stack.patch b/queue-6.8/x86-efistub-call-mixed-mode-boot-services-on-the-firmware-s-stack.patch
new file mode 100644 (file)
index 0000000..61d68b8
--- /dev/null
+++ b/queue-6.8/x86-efistub-call-mixed-mode-boot-services-on-the-firmware-s-stack.patch
@@ -0,0 +1,77 @@
+From cefcd4fe2e3aaf792c14c9e56dab89e3d7a65d02 Mon Sep 17 00:00:00 2001
+From: Ard Biesheuvel <ardb@kernel.org>
+Date: Fri, 22 Mar 2024 17:03:58 +0200
+Subject: x86/efistub: Call mixed mode boot services on the firmware's stack
+
+From: Ard Biesheuvel <ardb@kernel.org>
+
+commit cefcd4fe2e3aaf792c14c9e56dab89e3d7a65d02 upstream.
+
+Normally, the EFI stub calls into the EFI boot services using the stack
+that was live when the stub was entered. According to the UEFI spec,
+this stack needs to be at least 128k in size - this might seem large but
+all asynchronous processing and event handling in EFI runs from the same
+stack and so quite a lot of space may be used in practice.
+
+In mixed mode, the situation is a bit different: the bootloader calls
+the 32-bit EFI stub entry point, which calls the decompressor's 32-bit
+entry point, where the boot stack is set up, using a fixed allocation
+of 16k. This stack is still in use when the EFI stub is started in
+64-bit mode, and so all calls back into the EFI firmware will be using
+the decompressor's limited boot stack.
+
+Due to the placement of the boot stack right after the boot heap, any
+stack overruns have gone unnoticed. However, commit
+
+  5c4feadb0011983b ("x86/decompressor: Move global symbol references to C code")
+
+moved the definition of the boot heap into C code, and now the boot
+stack is placed right at the base of BSS, where any overruns will
+corrupt the end of the .data section.
+
+While it would be possible to work around this by increasing the size of
+the boot stack, doing so would affect all x86 systems, and mixed mode
+systems are a tiny (and shrinking) fraction of the x86 installed base.
+
+So instead, record the firmware stack pointer value when entering from
+the 32-bit firmware, and switch to this stack every time a EFI boot
+service call is made.
+
+Cc: <stable@kernel.org> # v6.1+
+Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ arch/x86/boot/compressed/efi_mixed.S |    9 +++++++++
+ 1 file changed, 9 insertions(+)
+
+--- a/arch/x86/boot/compressed/efi_mixed.S
++++ b/arch/x86/boot/compressed/efi_mixed.S
+@@ -49,6 +49,11 @@ SYM_FUNC_START(startup_64_mixed_mode)
+       lea     efi32_boot_args(%rip), %rdx
+       mov     0(%rdx), %edi
+       mov     4(%rdx), %esi
++
++      /* Switch to the firmware's stack */
++      movl    efi32_boot_sp(%rip), %esp
++      andl    $~7, %esp
++
+ #ifdef CONFIG_EFI_HANDOVER_PROTOCOL
+       mov     8(%rdx), %edx           // saved bootparams pointer
+       test    %edx, %edx
+@@ -254,6 +259,9 @@ SYM_FUNC_START_LOCAL(efi32_entry)
+       /* Store firmware IDT descriptor */
+       sidtl   (efi32_boot_idt - 1b)(%ebx)
+ 
++      /* Store firmware stack pointer */
++      movl    %esp, (efi32_boot_sp - 1b)(%ebx)
++
+       /* Store boot arguments */
+       leal    (efi32_boot_args - 1b)(%ebx), %ebx
+       movl    %ecx, 0(%ebx)
+@@ -318,5 +326,6 @@ SYM_DATA_END(efi32_boot_idt)
+ 
+ SYM_DATA_LOCAL(efi32_boot_cs, .word 0)
+ SYM_DATA_LOCAL(efi32_boot_ds, .word 0)
++SYM_DATA_LOCAL(efi32_boot_sp, .long 0)
+ SYM_DATA_LOCAL(efi32_boot_args, .long 0, 0, 0)
+ SYM_DATA(efi_is64, .byte 1)