kallsyms: make KSYM_NAME_LEN include space for trailing '\0'

KSYM_NAME_LEN is peculiar in that it does not include the space for the
trailing '\0', forcing all users to use KSYM_NAME_LEN + 1 when allocating
buffer.  This is nonsense and error-prone.  Moreover, when the caller
forgets that it's very likely to subtly bite back by corrupting the stack
because the last position of the buffer is always cleared to zero.

This patch increments KSYM_NAME_LEN by one and updates code accordingly.

* off-by-one bug in asm-powerpc/kprobes.h::kprobe_lookup_name() macro
  is fixed.

* Where MODULE_NAME_LEN and KSYM_NAME_LEN were used together,
  MODULE_NAME_LEN was treated as if it didn't include space for the
  trailing '\0'.  Fix it.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Acked-by: Paulo Marques <pmarques@grupopie.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

5 files changed, 17 insertions, 17 deletions

diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 0d662475dd9..474219a4192 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -152,7 +152,7 @@ static unsigned int get_symbol_offset(unsigned long pos)
 /* Lookup the address for this symbol. Returns 0 if not found. */
 unsigned long kallsyms_lookup_name(const char *name)
 {
-	char namebuf[KSYM_NAME_LEN+1];
+	char namebuf[KSYM_NAME_LEN];
 	unsigned long i;
 	unsigned int off;
 
@@ -248,7 +248,7 @@ const char *kallsyms_lookup(unsigned long addr,
 {
 	const char *msym;
 
-	namebuf[KSYM_NAME_LEN] = 0;
+	namebuf[KSYM_NAME_LEN - 1] = 0;
 	namebuf[0] = 0;
 
 	if (is_ksym_addr(addr)) {
@@ -265,7 +265,7 @@ const char *kallsyms_lookup(unsigned long addr,
 	/* see if it's in a module */
 	msym = module_address_lookup(addr, symbolsize, offset, modname);
 	if (msym)
-		return strncpy(namebuf, msym, KSYM_NAME_LEN);
+		return strncpy(namebuf, msym, KSYM_NAME_LEN - 1);
 
 	return NULL;
 }
@@ -273,7 +273,7 @@ const char *kallsyms_lookup(unsigned long addr,
 int lookup_symbol_name(unsigned long addr, char *symname)
 {
 	symname[0] = '\0';
-	symname[KSYM_NAME_LEN] = '\0';
+	symname[KSYM_NAME_LEN - 1] = '\0';
 
 	if (is_ksym_addr(addr)) {
 		unsigned long pos;
@@ -291,7 +291,7 @@ int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
 			unsigned long *offset, char *modname, char *name)
 {
 	name[0] = '\0';
-	name[KSYM_NAME_LEN] = '\0';
+	name[KSYM_NAME_LEN - 1] = '\0';
 
 	if (is_ksym_addr(addr)) {
 		unsigned long pos;
@@ -312,7 +312,7 @@ int sprint_symbol(char *buffer, unsigned long address)
 	char *modname;
 	const char *name;
 	unsigned long offset, size;
-	char namebuf[KSYM_NAME_LEN+1];
+	char namebuf[KSYM_NAME_LEN];
 
 	name = kallsyms_lookup(address, &size, &offset, &modname, namebuf);
 	if (!name)
@@ -342,8 +342,8 @@ struct kallsym_iter
 	unsigned long value;
 	unsigned int nameoff; /* If iterating in core kernel symbols */
 	char type;
-	char name[KSYM_NAME_LEN+1];
-	char module_name[MODULE_NAME_LEN + 1];
+	char name[KSYM_NAME_LEN];
+	char module_name[MODULE_NAME_LEN];
 	int exported;
 };
 
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 1a5ff2211d8..edba2ffb43d 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -379,7 +379,7 @@ get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4
 
 static void print_lock_name(struct lock_class *class)
 {
-	char str[KSYM_NAME_LEN + 1], c1, c2, c3, c4;
+	char str[KSYM_NAME_LEN], c1, c2, c3, c4;
 	const char *name;
 
 	get_usage_chars(class, &c1, &c2, &c3, &c4);
@@ -401,7 +401,7 @@ static void print_lock_name(struct lock_class *class)
 static void print_lockdep_cache(struct lockdep_map *lock)
 {
 	const char *name;
-	char str[KSYM_NAME_LEN + 1];
+	char str[KSYM_NAME_LEN];
 
 	name = lock->name;
 	if (!name)
diff --git a/kernel/module.c b/kernel/module.c
index 539fed9ac83..33c04ad5117 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2133,7 +2133,7 @@ int lookup_module_symbol_name(unsigned long addr, char *symname)
 			sym = get_ksymbol(mod, addr, NULL, NULL);
 			if (!sym)
 				goto out;
-			strlcpy(symname, sym, KSYM_NAME_LEN + 1);
+			strlcpy(symname, sym, KSYM_NAME_LEN);
 			mutex_unlock(&module_mutex);
 			return 0;
 		}
@@ -2158,9 +2158,9 @@ int lookup_module_symbol_attrs(unsigned long addr, unsigned long *size,
 			if (!sym)
 				goto out;
 			if (modname)
-				strlcpy(modname, mod->name, MODULE_NAME_LEN + 1);
+				strlcpy(modname, mod->name, MODULE_NAME_LEN);
 			if (name)
-				strlcpy(name, sym, KSYM_NAME_LEN + 1);
+				strlcpy(name, sym, KSYM_NAME_LEN);
 			mutex_unlock(&module_mutex);
 			return 0;
 		}
@@ -2181,8 +2181,8 @@ int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
 			*value = mod->symtab[symnum].st_value;
 			*type = mod->symtab[symnum].st_info;
 			strlcpy(name, mod->strtab + mod->symtab[symnum].st_name,
-				KSYM_NAME_LEN + 1);
-			strlcpy(module_name, mod->name, MODULE_NAME_LEN + 1);
+				KSYM_NAME_LEN);
+			strlcpy(module_name, mod->name, MODULE_NAME_LEN);
 			*exported = is_exported(name, mod);
 			mutex_unlock(&module_mutex);
 			return 0;
diff --git a/kernel/time/timer_list.c b/kernel/time/timer_list.c
index 8bbcfb77f7d..e5edc3a22a0 100644
--- a/kernel/time/timer_list.c
+++ b/kernel/time/timer_list.c
@@ -38,7 +38,7 @@ DECLARE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases);
 
 static void print_name_offset(struct seq_file *m, void *sym)
 {
-	char symname[KSYM_NAME_LEN+1];
+	char symname[KSYM_NAME_LEN];
 
 	if (lookup_symbol_name((unsigned long)sym, symname) < 0)
 		SEQ_printf(m, "<%p>", sym);
diff --git a/kernel/time/timer_stats.c b/kernel/time/timer_stats.c
index 9b8a826236d..8ed62fda16c 100644
--- a/kernel/time/timer_stats.c
+++ b/kernel/time/timer_stats.c
@@ -269,7 +269,7 @@ void timer_stats_update_stats(void *timer, pid_t pid, void *startf,
 
 static void print_name_offset(struct seq_file *m, unsigned long addr)
 {
-	char symname[KSYM_NAME_LEN+1];
+	char symname[KSYM_NAME_LEN];
 
 	if (lookup_symbol_name(addr, symname) < 0)
 		seq_printf(m, "<%p>", (void *)addr);