[PATCH] name_count array overrun

Steve Grubb
2006-09-07T17:59:37Z

Hello,

The below patch closes an unbounded use of name_count. This can lead to oopses
in some new file systems.

Signed-off-by: Steve Grubb <sgrubb@redhat.com>

diff -urp linux-2.6.17.x86_64.orig/kernel/auditsc.c linux-2.6.17.x86_64/kernel/auditsc.c
--- linux-2.6.17.x86_64.orig/kernel/auditsc.c 2006-08-29 11:21:20.000000000 -0400
+++ linux-2.6.17.x86_64/kernel/auditsc.c 2006-08-29 15:15:28.000000000 -0400
@@ -1281,7 +1281,15 @@ void __audit_inode(const char *name, con
* associated name? */
if (context->name_count >= AUDIT_NAMES - AUDIT_NAMES_RESERVED)
return;
- idx = context->name_count++;
+ idx = context->name_count;
+ if (context->name_count == (AUDIT_NAMES - 1)) {
+ printk(KERN_DEBUG
+ "name_count maxed and losing entry [%d]=%s\n",
+ context->name_count,
+ context->names[context->name_count].name ?:
+ "(null)");
+ } else
+ context->name_count++;
context->names[idx].name = NULL;
#if AUDIT_DEBUG
++context->ino_count;
@@ -1333,7 +1341,13 @@ void __audit_inode_child(const char *dna
}

update_context:
- idx = context->name_count++;
+ idx = context->name_count;
+ if (context->name_count == (AUDIT_NAMES - 1)) {
+ printk(KERN_DEBUG "name_count maxed and losing entry [%d]=%s\n",
+ context->name_count,
+ context->names[context->name_count].name ?: "(null)");
+ } else
+ context->name_count++;
#if AUDIT_DEBUG
context->ino_count++;
#endif
@@ -1351,7 +1365,15 @@ update_context:
/* A parent was not found in audit_names, so copy the inode data for the
* provided parent. */
if (!found_name) {
- idx = context->name_count++;
+ idx = context->name_count;
+ if (context->name_count == (AUDIT_NAMES - 1)) {
+ printk(KERN_DEBUG
+ "name_count maxed and losing entry [%d]=%s\n",
+ context->name_count,
+ context->names[context->name_count].name ?:
+ "(null)");
+ } else
+ context->name_count++;
#if AUDIT_DEBUG
context->ino_count++;
#endif