[PATCH -next,v3 0/2] Audit: fix warning and check priority early

[PATCH -next,v3 0/2] Audit: fix warning and check priority early

[Gaosheng Cui]

v3:
  drop the redundant commit message and add a Fixes tag to the first 
  patch
v2:
  audit: fix possible null-pointer dereference in audit_filter_rules
  audit: return early if the rule has a lower priority
v1:
  audit: return early if the rule has a lower priority

Gaosheng Cui (2):
  audit: fix possible null-pointer dereference in audit_filter_rules
  audit: return early if the rule has a lower priority

 kernel/auditsc.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

-- 
2.30.0


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[PATCH -next, v3 1/2] audit: fix possible null-pointer dereference in audit_filter_rules

[Gaosheng Cui]

Fix  possible null-pointer dereference in audit_filter_rules.

audit_filter_rules() error: we previously assumed 'ctx' could be null

Fixes: bf361231c295 ("audit: add saddr_fam filter field")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
---
 kernel/auditsc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 4ba3b8573ff4..42d4a4320526 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -647,7 +647,7 @@ static int audit_filter_rules(struct task_struct *tsk,
 			result = audit_comparator(audit_loginuid_set(tsk), f->op, f->val);
 			break;
 		case AUDIT_SADDR_FAM:
-			if (ctx->sockaddr)
+			if (ctx && ctx->sockaddr)
 				result = audit_comparator(ctx->sockaddr->ss_family,
 							  f->op, f->val);
 			break;
-- 
2.30.0


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[PATCH -next, v3 2/2] audit: return early if the rule has a lower priority

[Gaosheng Cui]

It is not necessary for audit_filter_rules() functions to check
audit fileds of the rule with a lower priority, and if we did,
there might be some unintended effects, such as the ctx->ppid
may be changed unexpectedly, so return early if the rule has
a lower priority.

Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
---
 kernel/auditsc.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 42d4a4320526..b517947bfa48 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -470,6 +470,9 @@ static int audit_filter_rules(struct task_struct *tsk,
 	u32 sid;
 	unsigned int sessionid;
 
+	if (ctx && rule->prio <= ctx->prio)
+		return 0;
+
 	cred = rcu_dereference_check(tsk->cred, tsk == current || task_creation);
 
 	for (i = 0; i < rule->field_count; i++) {
@@ -737,8 +740,6 @@ static int audit_filter_rules(struct task_struct *tsk,
 	}
 
 	if (ctx) {
-		if (rule->prio <= ctx->prio)
-			return 0;
 		if (rule->filterkey) {
 			kfree(ctx->filterkey);
 			ctx->filterkey = kstrdup(rule->filterkey, GFP_ATOMIC);
-- 
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Re: [PATCH -next, v3 1/2] audit: fix possible null-pointer dereference in audit_filter_rules

[Paul Moore]

On Sat, Oct 16, 2021 at 3:21 AM Gaosheng Cui <cuigaosheng1@huawei.com> wrote:
>
> Fix  possible null-pointer dereference in audit_filter_rules.
>
> audit_filter_rules() error: we previously assumed 'ctx' could be null
>
> Fixes: bf361231c295 ("audit: add saddr_fam filter field")
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
> ---
>  kernel/auditsc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Thank you for the patch; I added a stable tag and merged it into
audit/stable-5.15, I'll send it up to Linus later this week once it
has gone through some additional testing.

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Re: [PATCH -next, v3 2/2] audit: return early if the rule has a lower priority

[Paul Moore]

On Sat, Oct 16, 2021 at 3:21 AM Gaosheng Cui <cuigaosheng1@huawei.com> wrote:
>
> It is not necessary for audit_filter_rules() functions to check
> audit fileds of the rule with a lower priority, and if we did,
> there might be some unintended effects, such as the ctx->ppid
> may be changed unexpectedly, so return early if the rule has
> a lower priority.
>
> Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
> ---
>  kernel/auditsc.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)

Merged to audit/next, thanks!

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Re: [PATCH -next, v3 2/2] audit: return early if the rule has a lower priority

[Steve Grubb]

Hello,

On Saturday, October 16, 2021 3:23:51 AM EDT Gaosheng Cui wrote:
> It is not necessary for audit_filter_rules() functions to check
> audit fileds of the rule with a lower priority, and if we did,
> there might be some unintended effects, such as the ctx->ppid
> may be changed unexpectedly, so return early if the rule has
> a lower priority.
> 
> Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
> ---
>  kernel/auditsc.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index 42d4a4320526..b517947bfa48 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -470,6 +470,9 @@ static int audit_filter_rules(struct task_struct *tsk,
>  	u32 sid;
>  	unsigned int sessionid;
> 
> +	if (ctx && rule->prio <= ctx->prio)
> +		return 0;
> +

Just wondering something... If the first thing we do is to decide to return, 
should we have called the function in the first place? I wonder if this test 
should be used to break out of the rule iteration loops so that we don't keep 
calling only to return ?

-Steve

>  	cred = rcu_dereference_check(tsk->cred, tsk == current || 
task_creation);
> 
>  	for (i = 0; i < rule->field_count; i++) {
> @@ -737,8 +740,6 @@ static int audit_filter_rules(struct task_struct *tsk,
>  	}
> 
>  	if (ctx) {
> -		if (rule->prio <= ctx->prio)
> -			return 0;
>  		if (rule->filterkey) {
>  			kfree(ctx->filterkey);
>  			ctx->filterkey = kstrdup(rule->filterkey, GFP_ATOMIC);




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Re: [PATCH -next, v3 2/2] audit: return early if the rule has a lower priority

[Paul Moore]

On Tue, Oct 19, 2021 at 10:51 AM Steve Grubb <sgrubb@redhat.com> wrote:
> Just wondering something... If the first thing we do is to decide to return,
> should we have called the function in the first place? I wonder if this test
> should be used to break out of the rule iteration loops so that we don't keep
> calling only to return ?

Patches are welcome ... ;)

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