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Message-ID: <20230414071729.57312-1-zhengyejian1@huawei.com>
Date: Fri, 14 Apr 2023 15:17:29 +0800
From: Zheng Yejian <zhengyejian1@...wei.com>
To: <rostedt@...dmis.org>, <mhiramat@...nel.org>,
<linux-trace-kernel@...r.kernel.org>
CC: <linux-kernel@...r.kernel.org>, <zhengyejian1@...wei.com>
Subject: [PATCH] ring-buffer: Clearly check null ptr returned by rb_set_head_page()
In error case, 'buffer_page' returned by rb_set_head_page() is NULL,
currently check '&buffer_page->list' is equivalent to check 'buffer_page'
due to 'list' is the first member of 'buffer_page', but suppose it is not
some time, 'head_page' would be wild memory while check would be bypassed.
Signed-off-by: Zheng Yejian <zhengyejian1@...wei.com>
---
kernel/trace/ring_buffer.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 76a2d91eecad..025324df1f96 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2060,10 +2060,11 @@ rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer)
struct list_head *head_page, *prev_page, *r;
struct list_head *last_page, *first_page;
struct list_head *head_page_with_bit;
+ struct buffer_page *hpage = rb_set_head_page(cpu_buffer);
- head_page = &rb_set_head_page(cpu_buffer)->list;
- if (!head_page)
+ if (!hpage)
break;
+ head_page = &hpage->list;
prev_page = head_page->prev;
first_page = pages->next;
--
2.25.1
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