1 files changed, 70 insertions, 63 deletions

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 3b8129dd374c..24f37bab8bc1 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -49,10 +49,15 @@
 
 #include <asm/page.h>		/* for PAGE_SIZE */
 #include <asm/byteorder.h>	/* cpu_to_le16 */
+#include <asm/unaligned.h>
 
 #include <linux/string_helpers.h>
 #include "kstrtox.h"
 
+/* Disable pointer hashing if requested */
+bool no_hash_pointers __ro_after_init;
+EXPORT_SYMBOL_GPL(no_hash_pointers);
+
 static noinline unsigned long long simple_strntoull(const char *startp, size_t max_chars, char **endp, unsigned int base)
 {
 	const char *cp;
@@ -745,59 +750,42 @@ static int __init debug_boot_weak_hash_enable(char *str)
 }
 early_param("debug_boot_weak_hash", debug_boot_weak_hash_enable);
 
-static DEFINE_STATIC_KEY_TRUE(not_filled_random_ptr_key);
+static bool filled_random_ptr_key __read_mostly;
 static siphash_key_t ptr_key __read_mostly;
+static void fill_ptr_key_workfn(struct work_struct *work);
+static DECLARE_DELAYED_WORK(fill_ptr_key_work, fill_ptr_key_workfn);
 
-static void enable_ptr_key_workfn(struct work_struct *work)
+static void fill_ptr_key_workfn(struct work_struct *work)
 {
-	get_random_bytes(&ptr_key, sizeof(ptr_key));
-	/* Needs to run from preemptible context */
-	static_branch_disable(&not_filled_random_ptr_key);
-}
+	if (!rng_is_initialized()) {
+		queue_delayed_work(system_unbound_wq, &fill_ptr_key_work, HZ  * 2);
+		return;
+	}
 
-static DECLARE_WORK(enable_ptr_key_work, enable_ptr_key_workfn);
+	get_random_bytes(&ptr_key, sizeof(ptr_key));
 
-static void fill_random_ptr_key(struct random_ready_callback *unused)
-{
-	/* This may be in an interrupt handler. */
-	queue_work(system_unbound_wq, &enable_ptr_key_work);
+	/* Pairs with smp_rmb() before reading ptr_key. */
+	smp_wmb();
+	WRITE_ONCE(filled_random_ptr_key, true);
 }
 
-static struct random_ready_callback random_ready = {
-	.func = fill_random_ptr_key
-};
-
-static int __init initialize_ptr_random(void)
+static int __init vsprintf_init_hashval(void)
 {
-	int key_size = sizeof(ptr_key);
-	int ret;
-
-	/* Use hw RNG if available. */
-	if (get_random_bytes_arch(&ptr_key, key_size) == key_size) {
-		static_branch_disable(&not_filled_random_ptr_key);
-		return 0;
-	}
-
-	ret = add_random_ready_callback(&random_ready);
-	if (!ret) {
-		return 0;
-	} else if (ret == -EALREADY) {
-		/* This is in preemptible context */
-		enable_ptr_key_workfn(&enable_ptr_key_work);
-		return 0;
-	}
-
-	return ret;
+	fill_ptr_key_workfn(NULL);
+	return 0;
 }
-early_initcall(initialize_ptr_random);
+subsys_initcall(vsprintf_init_hashval)
 
 /* Maps a pointer to a 32 bit unique identifier. */
 static inline int __ptr_to_hashval(const void *ptr, unsigned long *hashval_out)
 {
 	unsigned long hashval;
 
-	if (static_branch_unlikely(&not_filled_random_ptr_key))
-		return -EAGAIN;
+	if (!READ_ONCE(filled_random_ptr_key))
+		return -EBUSY;
+
+	/* Pairs with smp_wmb() after writing ptr_key. */
+	smp_rmb();
 
 #ifdef CONFIG_64BIT
 	hashval = (unsigned long)siphash_1u64((u64)ptr, &ptr_key);
@@ -848,6 +836,19 @@ static char *ptr_to_id(char *buf, char *end, const void *ptr,
 	return pointer_string(buf, end, (const void *)hashval, spec);
 }
 
+static char *default_pointer(char *buf, char *end, const void *ptr,
+			     struct printf_spec spec)
+{
+	/*
+	 * default is to _not_ leak addresses, so hash before printing,
+	 * unless no_hash_pointers is specified on the command line.
+	 */
+	if (unlikely(no_hash_pointers))
+		return pointer_string(buf, end, ptr, spec);
+
+	return ptr_to_id(buf, end, ptr, spec);
+}
+
 int kptr_restrict __read_mostly;
 
 static noinline_for_stack
@@ -857,7 +858,7 @@ char *restricted_pointer(char *buf, char *end, const void *ptr,
 	switch (kptr_restrict) {
 	case 0:
 		/* Handle as %p, hash and do _not_ leak addresses. */
-		return ptr_to_id(buf, end, ptr, spec);
+		return default_pointer(buf, end, ptr, spec);
 	case 1: {
 		const struct cred *cred;
 
@@ -1193,7 +1194,7 @@ char *hex_string(char *buf, char *end, u8 *addr, struct printf_spec spec,
 }
 
 static noinline_for_stack
-char *bitmap_string(char *buf, char *end, unsigned long *bitmap,
+char *bitmap_string(char *buf, char *end, const unsigned long *bitmap,
 		    struct printf_spec spec, const char *fmt)
 {
 	const int CHUNKSZ = 32;
@@ -1237,7 +1238,7 @@ char *bitmap_string(char *buf, char *end, unsigned long *bitmap,
 }
 
 static noinline_for_stack
-char *bitmap_list_string(char *buf, char *end, unsigned long *bitmap,
+char *bitmap_list_string(char *buf, char *end, const unsigned long *bitmap,
 			 struct printf_spec spec, const char *fmt)
 {
 	int nr_bits = max_t(int, spec.field_width, 0);
@@ -1761,7 +1762,7 @@ char *fourcc_string(char *buf, char *end, const u32 *fourcc,
 	char output[sizeof("0123 little-endian (0x01234567)")];
 	char *p = output;
 	unsigned int i;
-	u32 val;
+	u32 orig, val;
 
 	if (fmt[1] != 'c' || fmt[2] != 'c')
 		return error_string(buf, end, "(%p4?)", spec);
@@ -1769,21 +1770,23 @@ char *fourcc_string(char *buf, char *end, const u32 *fourcc,
 	if (check_pointer(&buf, end, fourcc, spec))
 		return buf;
 
-	val = *fourcc & ~BIT(31);
+	orig = get_unaligned(fourcc);
+	val = orig & ~BIT(31);
 
-	for (i = 0; i < sizeof(*fourcc); i++) {
+	for (i = 0; i < sizeof(u32); i++) {
 		unsigned char c = val >> (i * 8);
 
 		/* Print non-control ASCII characters as-is, dot otherwise */
 		*p++ = isascii(c) && isprint(c) ? c : '.';
 	}
 
-	strcpy(p, *fourcc & BIT(31) ? " big-endian" : " little-endian");
+	*p++ = ' ';
+	strcpy(p, orig & BIT(31) ? "big-endian" : "little-endian");
 	p += strlen(p);
 
 	*p++ = ' ';
 	*p++ = '(';
-	p = special_hex_number(p, output + sizeof(output) - 2, *fourcc, sizeof(u32));
+	p = special_hex_number(p, output + sizeof(output) - 2, orig, sizeof(u32));
 	*p++ = ')';
 	*p = '\0';
 
@@ -2223,10 +2226,6 @@ char *fwnode_string(char *buf, char *end, struct fwnode_handle *fwnode,
 	return widen_string(buf, buf - buf_start, end, spec);
 }
 
-/* Disable pointer hashing if requested */
-bool no_hash_pointers __ro_after_init;
-EXPORT_SYMBOL_GPL(no_hash_pointers);
-
 int __init no_hash_pointers_enable(char *str)
 {
 	if (no_hash_pointers)
@@ -2252,6 +2251,9 @@ int __init no_hash_pointers_enable(char *str)
 }
 early_param("no_hash_pointers", no_hash_pointers_enable);
 
+/* Used for Rust formatting ('%pA'). */
+char *rust_fmt_argument(char *buf, char *end, void *ptr);
+
 /*
  * Show a '%p' thing.  A kernel extension is that the '%p' is followed
  * by an extra set of alphanumeric characters that are extended format
@@ -2378,6 +2380,10 @@ early_param("no_hash_pointers", no_hash_pointers_enable);
  *
  * Note: The default behaviour (unadorned %p) is to hash the address,
  * rendering it useful as a unique identifier.
+ *
+ * There is also a '%pA' format specifier, but it is only intended to be used
+ * from Rust code to format core::fmt::Arguments. Do *not* use it from C.
+ * See rust/kernel/print.rs for details.
  */
 static noinline_for_stack
 char *pointer(const char *fmt, char *buf, char *end, void *ptr,
@@ -2450,12 +2456,18 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
 		return device_node_string(buf, end, ptr, spec, fmt + 1);
 	case 'f':
 		return fwnode_string(buf, end, ptr, spec, fmt + 1);
+	case 'A':
+		if (!IS_ENABLED(CONFIG_RUST)) {
+			WARN_ONCE(1, "Please remove %%pA from non-Rust code\n");
+			return error_string(buf, end, "(%pA?)", spec);
+		}
+		return rust_fmt_argument(buf, end, ptr);
 	case 'x':
 		return pointer_string(buf, end, ptr, spec);
 	case 'e':
 		/* %pe with a non-ERR_PTR gets treated as plain %p */
 		if (!IS_ERR(ptr))
-			break;
+			return default_pointer(buf, end, ptr, spec);
 		return err_ptr(buf, end, ptr, spec);
 	case 'u':
 	case 'k':
@@ -2465,16 +2477,9 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
 		default:
 			return error_string(buf, end, "(einval)", spec);
 		}
+	default:
+		return default_pointer(buf, end, ptr, spec);
 	}
-
-	/*
-	 * default is to _not_ leak addresses, so hash before printing,
-	 * unless no_hash_pointers is specified on the command line.
-	 */
-	if (unlikely(no_hash_pointers))
-		return pointer_string(buf, end, ptr, spec);
-	else
-		return ptr_to_id(buf, end, ptr, spec);
 }
 
 /*
@@ -2895,13 +2900,15 @@ int vscnprintf(char *buf, size_t size, const char *fmt, va_list args)
 {
 	int i;
 
+	if (unlikely(!size))
+		return 0;
+
 	i = vsnprintf(buf, size, fmt, args);
 
 	if (likely(i < size))
 		return i;
-	if (size != 0)
-		return size - 1;
-	return 0;
+
+	return size - 1;
 }
 EXPORT_SYMBOL(vscnprintf);