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 conflicts due to lack of 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(-)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index aecf4342f67c..063e4ade1680 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1593,10 +1593,17 @@ static int check_kprobe_address_safe(struct kprobe *p, jump_label_lock(); preempt_disable();
- /* Ensure it is not in reserved area nor out of text */ - if (!(core_kernel_text((unsigned long) p->addr) || - is_module_text_address((unsigned long) p->addr)) || - in_gate_area_no_mm((unsigned long) p->addr) || + /* Ensure the address is in a text area, and find a module if exists. */ + *probed_mod = NULL; + if (!core_kernel_text((unsigned long) p->addr)) { + *probed_mod = __module_text_address((unsigned long) p->addr); + if (!(*probed_mod)) { + ret = -EINVAL; + goto out; + } + } + /* Ensure it is not in reserved area. */ + if (in_gate_area_no_mm((unsigned long) p->addr) || within_kprobe_blacklist((unsigned long) p->addr) || jump_label_text_reserved(p->addr, p->addr) || find_bug((unsigned long)p->addr)) { @@ -1604,8 +1611,7 @@ static int check_kprobe_address_safe(struct kprobe *p, goto out; }
- /* Check if are we probing a module */ - *probed_mod = __module_text_address((unsigned long) p->addr); + /* Get module refcount and reject __init functions for loaded modules. */ if (*probed_mod) { /* * We must hold a refcount of the probed module while updating