Re: [PATCH 5.15.y] kprobes: Fix possible use-after-free issue on kprobe registration

[Greg KH <greg@kroah.com>]

On Tue, Apr 16, 2024 at 10:16:54AM +0800, Zheng Yejian wrote:
> commit 325f3fb551f8cd672dbbfc4cf58b14f9ee3fc9e8 upstream.
> 
> When unloading a module, its state is changing MODULE_STATE_LIVE ->
>  MODULE_STATE_GOING -> MODULE_STATE_UNFORMED. Each change will take
> a time. `is_module_text_address()` and `__module_text_address()`
> works with MODULE_STATE_LIVE and MODULE_STATE_GOING.
> If we use `is_module_text_address()` and `__module_text_address()`
> separately, there is a chance that the first one is succeeded but the
> next one is failed because module->state becomes MODULE_STATE_UNFORMED
> between those operations.
> 
> In `check_kprobe_address_safe()`, if the second `__module_text_address()`
> is failed, that is ignored because it expected a kernel_text address.
> But it may have failed simply because module->state has been changed
> to MODULE_STATE_UNFORMED. In this case, arm_kprobe() will try to modify
> non-exist module text address (use-after-free).
> 
> To fix this problem, we should not use separated `is_module_text_address()`
> and `__module_text_address()`, but use only `__module_text_address()`
> once and do `try_module_get(module)` which is only available with
> MODULE_STATE_LIVE.
> 
> Link: https://lore.kernel.org/all/20240410015802.265220-1-zhengyejian1@huawei.com/
> 
> Fixes: 28f6c37a2910 ("kprobes: Forbid probing on trampoline and BPF code areas")
> Cc: stable@vger.kernel.org
> Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> [Fix conflict due to lack dependency
> commit 223a76b268c9 ("kprobes: Fix coding style issues")]
> Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
> ---
>  kernel/kprobes.c | 18 ++++++++++++------
>  1 file changed, 12 insertions(+), 6 deletions(-)

All now queued up, thanks.

greg k-h