RISC-V: hwprobe: Fix vDSO SIGSEGV

A hwprobe pair key is signed, but the hwprobe vDSO function was only checking that the upper bound was valid. In order to help avoid this type of problem in the future, and in anticipation of this check becoming more complicated with sparse keys, introduce and use a "key is valid" predicate function for the check. Fixes: aa5af0a ("RISC-V: Add hwprobe vDSO function and data") Signed-off-by: Andrew Jones <[email protected]> Reviewed-by: Evan Green <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Palmer Dabbelt <[email protected]>
niw · Nov 2, 2023 · e1c05b3 · e1c05b3
1 parent 6533010
commit e1c05b3
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Showing 2 changed files with 6 additions and 1 deletion.
diff --git a/arch/riscv/include/asm/hwprobe.h b/arch/riscv/include/asm/hwprobe.h
@@ -10,4 +10,9 @@
 
 #define RISCV_HWPROBE_MAX_KEY 6
 
+static inline bool riscv_hwprobe_key_is_valid(__s64 key)
+{
+	return key >= 0 && key <= RISCV_HWPROBE_MAX_KEY;
+}
+
 #endif
diff --git a/arch/riscv/kernel/vdso/hwprobe.c b/arch/riscv/kernel/vdso/hwprobe.c
@@ -37,7 +37,7 @@ int __vdso_riscv_hwprobe(struct riscv_hwprobe *pairs, size_t pair_count,
 
 	/* This is something we can handle, fill out the pairs. */
 	while (p < end) {
-		if (p->key <= RISCV_HWPROBE_MAX_KEY) {
+		if (riscv_hwprobe_key_is_valid(p->key)) {
 			p->value = avd->all_cpu_hwprobe_values[p->key];
 
 		} else {