linux-kernel - [PATCH] lib/error-inject: Traverse list with mutex

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Message-Id: <20220620100244.82896-1-wuchi.zero@gmail.com>
Date:   Mon, 20 Jun 2022 18:02:44 +0800
From:   wuchi <wuchi.zero@...il.com>
To:     mhiramat@...nel.org, kafai@...com, songliubraving@...com,
        yhs@...com, john.fastabend@...il.com, kpsingh@...nel.org
Cc:     akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, bpf@...r.kernel.org
Subject: [PATCH] lib/error-inject: Traverse list with mutex

Traversing list without mutex in get_injectable_error_type will
race with the following code:
    list_del_init(&ent->list)
    kfree(ent)
in module_unload_ei_list. So fix that.

Signed-off-by: wuchi <wuchi.zero@...il.com>
---
 lib/error-inject.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/lib/error-inject.c b/lib/error-inject.c
index 4a4f1278c419..1afca1b1cdea 100644
--- a/lib/error-inject.c
+++ b/lib/error-inject.c
@@ -40,12 +40,18 @@ bool within_error_injection_list(unsigned long addr)
 int get_injectable_error_type(unsigned long addr)
 {
 	struct ei_entry *ent;
+	int ei_type = EI_ETYPE_NONE;
 
+	mutex_lock(&ei_mutex);
 	list_for_each_entry(ent, &error_injection_list, list) {
-		if (addr >= ent->start_addr && addr < ent->end_addr)
-			return ent->etype;
+		if (addr >= ent->start_addr && addr < ent->end_addr) {
+			ei_type = ent->etype;
+			break;
+		}
 	}
-	return EI_ETYPE_NONE;
+	mutex_unlock(&ei_mutex);
+
+	return ei_type;
 }
 
 /*
-- 
2.20.1