On Mon, Jan 22, 2024 at 02:30:31PM +0300, Fedor Pchelkin wrote:
From: "Masami Hiramatsu (Google)" mhiramat@kernel.org
commit 4fbd2f83fda0ca44a2ec6421ca3508b355b31858 upstream.
Since forcibly unoptimized kprobes will be put on the freeing_list directly in the unoptimize_kprobe(), do_unoptimize_kprobes() must continue to check the freeing_list even if unoptimizing_list is empty.
This bug can happen if a kprobe is put in an instruction which is in the middle of the jump-replaced instruction sequence of an optprobe, *and* the optprobe is recently unregistered and queued on unoptimizing_list. In this case, the optprobe will be unoptimized forcibly (means immediately) and put it into the freeing_list, expecting the optprobe will be handled in do_unoptimize_kprobe(). But if there is no other optprobes on the unoptimizing_list, current code returns from the do_unoptimize_kprobe() soon and does not handle the optprobe which is on the freeing_list. Then the optprobe will hit the WARN_ON_ONCE() in the do_free_cleaned_kprobes(), because it is not handled in the latter loop of the do_unoptimize_kprobe().
To solve this issue, do not return from do_unoptimize_kprobes() immediately even if unoptimizing_list is empty.
Moreover, this change affects another case. kill_optimized_kprobes() expects kprobe_optimizer() will just free the optprobe on freeing_list. So I changed it to just do list_move() to freeing_list if optprobes are on unoptimizing list. And the do_unoptimize_kprobe() will skip arch_disarm_kprobe() if the probe on freeing_list has gone flag.
Link: https://lore.kernel.org/all/Y8URdIfVr3pq2X8w@xpf.sh.intel.com/ Link: https://lore.kernel.org/all/167448024501.3253718.13037333683110512967.stgit@...
Fixes: e4add247789e ("kprobes: Fix optimize_kprobe()/unoptimize_kprobe() cancellation logic") Reported-by: Pengfei Xu pengfei.xu@intel.com Signed-off-by: Masami Hiramatsu (Google) mhiramat@kernel.org Cc: stable@vger.kernel.org Acked-by: Steven Rostedt (Google) rostedt@goodmis.org [fp: adjust comment conflict regarding commit 223a76b268c9 ("kprobes: Fix coding style issues")] Signed-off-by: Fedor Pchelkin pchelkin@ispras.ru
kernel/kprobes.c | 23 ++++++++++------------- 1 file changed, 10 insertions(+), 13 deletions(-)
Now queued up, thanks.
greg k-h