[PATCH 5.15 067/374] powerpc: Mark .opd section read-only

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5.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Christophe Leroy <christophe.leroy@xxxxxxxxxx>

[ Upstream commit 3091f5fc5f1df7741ddf326561384e0997eca2a1 ]

.opd section contains function descriptors used to locate
functions in the kernel. If someone is able to modify a
function descriptor he will be able to run arbitrary
kernel function instead of another.

To avoid that, move .opd section inside read-only memory.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/3cd40b682fb6f75bb40947b55ca0bac20cb3f995.1634136222.git.christophe.leroy@xxxxxxxxxx
Stable-dep-of: 1b1e38002648 ("powerpc: add crtsavres.o to always-y instead of extra-y")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 arch/powerpc/kernel/vmlinux.lds.S | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index d4531902d8c6..d8301ce7c675 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -148,6 +148,12 @@ SECTIONS
 	SOFT_MASK_TABLE(8)
 	RESTART_TABLE(8)
 
+	.opd : AT(ADDR(.opd) - LOAD_OFFSET) {
+		__start_opd = .;
+		KEEP(*(.opd))
+		__end_opd = .;
+	}
+
 	. = ALIGN(8);
 	__stf_entry_barrier_fixup : AT(ADDR(__stf_entry_barrier_fixup) - LOAD_OFFSET) {
 		__start___stf_entry_barrier_fixup = .;
@@ -346,12 +352,6 @@ SECTIONS
 		*(.branch_lt)
 	}
 
-	.opd : AT(ADDR(.opd) - LOAD_OFFSET) {
-		__start_opd = .;
-		KEEP(*(.opd))
-		__end_opd = .;
-	}
-
 	. = ALIGN(256);
 	.got : AT(ADDR(.got) - LOAD_OFFSET) {
 		__toc_start = .;
-- 
2.43.0







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