Commit 625ed527 authored by Zheng Yejian's avatar Zheng Yejian Committed by Steven Rostedt (Google)
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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.

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



Cc: <mhiramat@kernel.org>
Signed-off-by: default avatarZheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 88fe1ec7

kernel/trace/ring_buffer.c

+3 −2
Original line number Diff line number Diff line
@@ -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;