From: Steven Rostedt (Google) Date: Mon, 11 Dec 2023 03:12:50 +0000 (-0500) Subject: ring-buffer: Fix memory leak of free page X-Git-Tag: v6.6.17~1862 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=b02bf0d952ad237444d91881adc56a75912e5e7a;p=platform%2Fkernel%2Flinux-rpi.git ring-buffer: Fix memory leak of free page commit 17d801758157bec93f26faaf5ff1a8b9a552d67a upstream. Reading the ring buffer does a swap of a sub-buffer within the ring buffer with a empty sub-buffer. This allows the reader to have full access to the content of the sub-buffer that was swapped out without having to worry about contention with the writer. The readers call ring_buffer_alloc_read_page() to allocate a page that will be used to swap with the ring buffer. When the code is finished with the reader page, it calls ring_buffer_free_read_page(). Instead of freeing the page, it stores it as a spare. Then next call to ring_buffer_alloc_read_page() will return this spare instead of calling into the memory management system to allocate a new page. Unfortunately, on freeing of the ring buffer, this spare page is not freed, and causes a memory leak. Link: https://lore.kernel.org/linux-trace-kernel/20231210221250.7b9cc83c@rorschach.local.home Cc: stable@vger.kernel.org Cc: Mark Rutland Cc: Mathieu Desnoyers Fixes: 73a757e63114d ("ring-buffer: Return reader page back into existing ring buffer") Acked-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman --- diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index f1ef432..be41f48 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1787,6 +1787,8 @@ static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) free_buffer_page(bpage); } + free_page((unsigned long)cpu_buffer->free_page); + kfree(cpu_buffer); }