From: Daniil Tatianin d-tatianin@yandex-team.ru

rb_head_page_deactivate() expects cpu_buffer to contain a valid list of ->pages, so verify that the list is actually present before calling it.

Found by Linux Verification Center (linuxtesting.org) with the SVACE static analysis tool.

Link: https://lkml.kernel.org/r/20221114143129.3534443-1-d-tatianin@yandex-team.ru

Cc: stable@vger.kernel.org Fixes: 77ae365eca895 ("ring-buffer: make lockless") Signed-off-by: Daniil Tatianin d-tatianin@yandex-team.ru Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org --- kernel/trace/ring_buffer.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index a19369c4d8df..b21bf14bae9b 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1802,9 +1802,9 @@ static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer)

free_buffer_page(cpu_buffer->reader_page);

- rb_head_page_deactivate(cpu_buffer); - if (head) { + rb_head_page_deactivate(cpu_buffer); + list_for_each_entry_safe(bpage, tmp, head, list) { list_del_init(&bpage->list); free_buffer_page(bpage);