From 4e84f18db19589074cbc0b8bda353eb2314a1a01 Mon Sep 17 00:00:00 2001
From: Anders Kaseorg <andersk@mit.edu>
Date: Mon, 23 Jun 2008 21:56:36 -0400
Subject: [PATCH] Fix various off-by-one comparison bugs.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>
---
 kmodsrc/ksplice.c | 15 +++++++++------
 kmodsrc/ksplice.h |  2 +-
 objcommon.h       |  7 +++++--
 3 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/kmodsrc/ksplice.c b/kmodsrc/ksplice.c
index b414957..7b4194b 100644
--- a/kmodsrc/ksplice.c
+++ b/kmodsrc/ksplice.c
@@ -324,16 +324,19 @@ int check_address_for_conflict(struct module_pack *pack, long addr)
 	struct ksplice_size *s = pack->primary_sizes;
 	struct safety_record *rec;
 
+	/* It is safe for addr to point to the beginning of a patched
+	   function, because that location will be overwritten with a
+	   trampoline. */
 	list_for_each_entry(rec, pack->safety_records, list) {
 		if (rec->care == 1 && addr > rec->addr
-		    && addr <= (rec->addr + rec->size)) {
+		    && addr < rec->addr + rec->size) {
 			ksplice_debug(2, "[<-- CONFLICT] ");
 			return -EAGAIN;
 		}
 	}
 	for (; s->name != NULL; s++) {
-		if (addr > s->thismod_addr
-		    && addr <= (s->thismod_addr + s->size)) {
+		if (addr >= s->thismod_addr
+		    && addr < s->thismod_addr + s->size) {
 			ksplice_debug(2, "[<-- CONFLICT] ");
 			return -EAGAIN;
 		}
@@ -1077,13 +1080,13 @@ void set_temp_myst_relocs(struct module_pack *pack, int status_val)
 
 int starts_with(const char *str, const char *prefix)
 {
-	return !strncmp(str, prefix, strlen(prefix));
+	return strncmp(str, prefix, strlen(prefix)) == 0;
 }
 
 int ends_with(const char *str, const char *suffix)
 {
-	return strlen(str) > strlen(suffix) &&
-	    !strcmp(&str[strlen(str) - strlen(suffix)], suffix);
+	return strlen(str) >= strlen(suffix) &&
+	    strcmp(&str[strlen(str) - strlen(suffix)], suffix) == 0;
 }
 
 int label_offset(const char *sym_name)
diff --git a/kmodsrc/ksplice.h b/kmodsrc/ksplice.h
index 863e833..258e47e 100644
--- a/kmodsrc/ksplice.h
+++ b/kmodsrc/ksplice.h
@@ -81,7 +81,7 @@ static inline int virtual_address_mapped(long addr)
 	pmd_t *pmd;
 	pte_t *ptep;
 
-	if (addr > init_mm.start_code && addr < init_mm.end_code)
+	if (addr >= init_mm.start_code && addr < init_mm.end_code)
 		return 1;
 
 	pgd = pgd_offset_k(addr);
diff --git a/objcommon.h b/objcommon.h
index b7575a9..7785024 100644
--- a/objcommon.h
+++ b/objcommon.h
@@ -24,8 +24,11 @@ struct supersect {
 long get_syms(bfd *abfd, asymbol ***syms_ptr);
 struct supersect *fetch_supersect(bfd *abfd, asection *sect, asymbol **sympp);
 
-#define starts_with(str, prefix) (!strncmp(str, prefix, strlen(prefix)))
-#define ends_with(str, suffix) (strlen(str) > strlen(suffix) && !strcmp(&str[strlen(str)-strlen(suffix)], suffix))
+#define starts_with(str, prefix)			\
+	(strncmp(str, prefix, strlen(prefix)) == 0)
+#define ends_with(str, suffix)						\
+	(strlen(str) >= strlen(suffix) &&				\
+	 strcmp(&str[strlen(str) - strlen(suffix)], suffix) == 0)
 
 int label_offset(const char *sym_name);
 const char *only_label(const char *sym_name);
-- 
2.11.4.GIT