1 files changed, 15 insertions, 3 deletions

diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c
index f713e2fc4d75..f32359cffb01 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));
 
@@ -96,15 +96,27 @@ 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 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)
+                if (sval < S16_MIN || sval > S16_MAX)
                         return -ERANGE;
                 break;
         case 32:
                 *(s32 *)place = sval;
-                if (sval < S32_MIN || sval > U32_MAX)
+                if (sval < S32_MIN || sval > S32_MAX)
                         return -ERANGE;
                 break;
         case 64: