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