From 625ed52717603f0de4c8b5cf163a3bba5cd9a362 Mon Sep 17 00:00:00 2001 From: Zheng Yejian Date: Fri, 14 Apr 2023 15:17:29 +0800 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. Link: https://lore.kernel.org/linux-trace-kernel/20230414071729.57312-1-zhengyejian1@huawei.com Cc: Signed-off-by: Zheng Yejian Signed-off-by: Steven Rostedt (Google) --- 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 2d5c3caff32d7..58be5b409f72f 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -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; -- 2.30.2