1 files changed, 39 insertions, 5 deletions

diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c
index f713e2fc4d75..dd080837e6a9 100644
--- a/arch/arm64/kernel/module.c
+++ b/arch/arm64/kernel/module.c
@@ -56,7 +56,7 @@ void *module_alloc(unsigned long size)
 		 * can simply omit this fallback in that case.
 		 */
 		p = __vmalloc_node_range(size, MODULE_ALIGN, module_alloc_base,
-				module_alloc_base + SZ_4G, GFP_KERNEL,
+				module_alloc_base + SZ_2G, GFP_KERNEL,
 				PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
 				__builtin_return_address(0));
 
@@ -96,16 +96,50 @@ static int reloc_data(enum aarch64_reloc_op op, void *place, u64 val, int len)
 {
 	s64 sval = do_reloc(op, place, val);
 
+	/*
+	 * The ELF psABI for AArch64 documents the 16-bit and 32-bit place
+	 * relative and absolute relocations as having a range of [-2^15, 2^16)
+	 * or [-2^31, 2^32), respectively. However, in order to be able to
+	 * detect overflows reliably, we have to choose whether we interpret
+	 * such quantities as signed or as unsigned, and stick with it.
+	 * The way we organize our address space requires a signed
+	 * interpretation of 32-bit relative references, so let's use that
+	 * for all R_AARCH64_PRELxx relocations. This means our upper
+	 * bound for overflow detection should be Sxx_MAX rather than Uxx_MAX.
+	 */
+
 	switch (len) {
 	case 16:
 		*(s16 *)place = sval;
-		if (sval < S16_MIN || sval > U16_MAX)
-			return -ERANGE;
+		switch (op) {
+		case RELOC_OP_ABS:
+			if (sval < 0 || sval > U16_MAX)
+				return -ERANGE;
+			break;
+		case RELOC_OP_PREL:
+			if (sval < S16_MIN || sval > S16_MAX)
+				return -ERANGE;
+			break;
+		default:
+			pr_err("Invalid 16-bit data relocation (%d)\n", op);
+			return 0;
+		}
 		break;
 	case 32:
 		*(s32 *)place = sval;
-		if (sval < S32_MIN || sval > U32_MAX)
-			return -ERANGE;
+		switch (op) {
+		case RELOC_OP_ABS:
+			if (sval < 0 || sval > U32_MAX)
+				return -ERANGE;
+			break;
+		case RELOC_OP_PREL:
+			if (sval < S32_MIN || sval > S32_MAX)
+				return -ERANGE;
+			break;
+		default:
+			pr_err("Invalid 32-bit data relocation (%d)\n", op);
+			return 0;
+		}
 		break;
 	case 64:
 		*(s64 *)place = sval;