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ring-buffer: Clearly check null ptr returned by rb_set_head_page()

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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.

Link: https://lore.kernel.org/linux-trace-kernel/20230414071729.57312-1-zhengyejian1@huawei.com

Cc: <mhiramat@kernel.org>
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Zheng Yejian 2023-04-14 15:17:29 +08:00 committed by Steven Rostedt (Google)
parent 88fe1ec75f
commit 625ed52717
1 changed files with 3 additions and 2 deletions
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5
kernel/trace/ring_buffer.c
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@ -2054,10 +2054,11 @@ 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;