grub2/0189-grub_dl_load_segments-page-align-the-tramp-GOT-areas.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Laszlo Ersek <lersek@redhat.com>
Date: Fri, 7 Apr 2023 16:56:09 +0200
Subject: [PATCH] grub_dl_load_segments(): page-align the tramp/GOT areas too

The tramp/GOT write-protection in grub_dl_set_mem_attrs() requires that
the tramp/GOT areas of the module image *not* share a page with any other
memory allocations. Page-align the tramp/GOT areas, while satisfying their
intrinsic alignment requirements too.

Fixes: 887f1d8fa976 (modules: load module sections at page-aligned addresses)
Fixes: ad1b904d325b (nx: set page permissions for loaded modules.)
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
---
 grub-core/kern/dl.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/grub-core/kern/dl.c b/grub-core/kern/dl.c
index bad0ad4b945..c55f0ecf931 100644
--- a/grub-core/kern/dl.c
+++ b/grub-core/kern/dl.c
@@ -272,7 +272,9 @@ grub_dl_load_segments (grub_dl_t mod, const Elf_Ehdr *e)
 #if !defined (__i386__) && !defined (__x86_64__) && !defined(__riscv) && \
   !defined (__loongarch__)
   grub_size_t tramp;
+  grub_size_t tramp_align;
   grub_size_t got;
+  grub_size_t got_align;
   grub_err_t err;
 #endif
   char *ptr;
@@ -304,12 +306,18 @@ grub_dl_load_segments (grub_dl_t mod, const Elf_Ehdr *e)
   err = grub_arch_dl_get_tramp_got_size (e, &tramp, &got);
   if (err)
     return err;
-  tsize += ALIGN_UP (tramp, GRUB_ARCH_DL_TRAMP_ALIGN);
-  if (talign < GRUB_ARCH_DL_TRAMP_ALIGN)
-    talign = GRUB_ARCH_DL_TRAMP_ALIGN;
-  tsize += ALIGN_UP (got, GRUB_ARCH_DL_GOT_ALIGN);
-  if (talign < GRUB_ARCH_DL_GOT_ALIGN)
-    talign = GRUB_ARCH_DL_GOT_ALIGN;
+  tramp_align = GRUB_ARCH_DL_TRAMP_ALIGN;
+  if (tramp_align < arch_addralign)
+    tramp_align = arch_addralign;
+  tsize += ALIGN_UP (tramp, tramp_align);
+  if (talign < tramp_align)
+    talign = tramp_align;
+  got_align = GRUB_ARCH_DL_GOT_ALIGN;
+  if (got_align < arch_addralign)
+    got_align = arch_addralign;
+  tsize += ALIGN_UP (got, got_align);
+  if (talign < got_align)
+    talign = got_align;
 #endif
 
 #ifdef GRUB_MACHINE_EMU
@@ -370,11 +378,11 @@ grub_dl_load_segments (grub_dl_t mod, const Elf_Ehdr *e)
     }
 #if !defined (__i386__) && !defined (__x86_64__) && !defined(__riscv) && \
   !defined (__loongarch__)
-  ptr = (char *) ALIGN_UP ((grub_addr_t) ptr, GRUB_ARCH_DL_TRAMP_ALIGN);
+  ptr = (char *) ALIGN_UP ((grub_addr_t) ptr, tramp_align);
   mod->tramp = ptr;
   mod->trampptr = ptr;
   ptr += tramp;
-  ptr = (char *) ALIGN_UP ((grub_addr_t) ptr, GRUB_ARCH_DL_GOT_ALIGN);
+  ptr = (char *) ALIGN_UP ((grub_addr_t) ptr, got_align);
   mod->got = ptr;
   mod->gotptr = ptr;
   ptr += got;