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>

2 files changed, 5 insertions, 5 deletions

diff --git a/include/asm-powerpc/kprobes.h b/include/asm-powerpc/kprobes.h
index b0e40ff32ee0..9537fda238b8 100644
--- a/include/asm-powerpc/kprobes.h
+++ b/include/asm-powerpc/kprobes.h
@@ -65,10 +65,10 @@ typedef unsigned int kprobe_opcode_t;
                 } else if (name[0] != '.')                              \
                         addr = *(kprobe_opcode_t **)addr;               \
         } else {                                                        \
-                char dot_name[KSYM_NAME_LEN+1];                         \
+                char dot_name[KSYM_NAME_LEN];                           \
                 dot_name[0] = '.';                                      \
                 dot_name[1] = '\0';                                     \
-                strncat(dot_name, name, KSYM_NAME_LEN);                 \
+                strncat(dot_name, name, KSYM_NAME_LEN - 2);             \
                 addr = (kprobe_opcode_t *)kallsyms_lookup_name(dot_name); \
         }                                                               \
 }
diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
index 5f06527dca21..f73de6fb5c68 100644
--- a/include/linux/kallsyms.h
+++ b/include/linux/kallsyms.h
@@ -7,9 +7,9 @@
 
 #include <linux/errno.h>
 
-#define KSYM_NAME_LEN 127
-#define KSYM_SYMBOL_LEN (sizeof("%s+%#lx/%#lx [%s]") + KSYM_NAME_LEN +  \
-                         2*(BITS_PER_LONG*3/10) + MODULE_NAME_LEN + 1)
+#define KSYM_NAME_LEN 128
+#define KSYM_SYMBOL_LEN (sizeof("%s+%#lx/%#lx [%s]") + (KSYM_NAME_LEN - 1) + \
+                         2*(BITS_PER_LONG*3/10) + (MODULE_NAME_LEN - 1) + 1)
 
 #ifdef CONFIG_KALLSYMS
 /* Lookup the address for a symbol. Returns 0 if not found. */