[PATCH] Fix the kernel panic of audit_filter_task when AUDIT_PERM or AUDIT_FILETYPE field
is set
When calling audit_filter_task(), it calls audit_filter_rules() with audit_context is
NULL.
If the AUDIT_PERM or AUDIT_FILETYPE field is set, audit_match_perm() or
audit_match_filetype() will use ctx->xx.
But the ctx is NULL in this condition, so kernel will panic.
Signed-off-by: Zhang Xiliang <zhangxiliang(a)cn.fujitsu.com>
---
 kernel/auditsc.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 012c94e..29b6964 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -243,6 +243,8 @@ static inline int open_arg(int flags, int mask)
 
 static int audit_match_perm(struct audit_context *ctx, int mask)
 {
+	if(!ctx)
+		return 0;
 	unsigned n = ctx->major;
 	switch (audit_classify_syscall(ctx->arch, n)) {
 	case 0:	/* native */
@@ -284,6 +286,8 @@ static int audit_match_filetype(struct audit_context *ctx, int which)
 {
 	unsigned index = which & ~S_IFMT;
 	mode_t mode = which & S_IFMT;
+	if(!ctx)
+		return 0;
 	if (index >= ctx->name_count)
 		return 0;
 	if (ctx->names[index].ino == -1)
zhangxiliang said the following on 2008-08-01 19:15:
 When calling audit_filter_task(), it calls audit_filter_rules() with
audit_context is NULL.
 If the key field is set, the result in audit_filter_rules() will be set to 1 and 
 ctx->filterkey will be set to key.
 But the ctx is NULL in this condition, so kernel will panic.
 
 Signed-off-by: Zhang Xiliang <zhangxiliang(a)cn.fujitsu.com>
 ---
  kernel/auditsc.c |    2 +-
  1 files changed, 1 insertions(+), 1 deletions(-)
 
 diff --git a/kernel/auditsc.c b/kernel/auditsc.c
 index 4699950..012c94e 100644
 --- a/kernel/auditsc.c
 +++ b/kernel/auditsc.c
 @@ -610,7 +610,7 @@ static int audit_filter_rules(struct task_struct *tsk,
  		if (!result)
  			return 0;
  	}
 -	if (rule->filterkey)
 +	if (rule->filterkey && ctx)
  		ctx->filterkey = kstrdup(rule->filterkey, GFP_ATOMIC);
  	switch (rule->action) {
  	case AUDIT_NEVER:    *state = AUDIT_DISABLED;	    break;
 
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