There is once warn in __arm_kprobe_ftrace() on:
ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 0, 0);
if (WARN_ONCE(..., "Failed to arm kprobe-ftrace at %pS (error %d)\n", ...)
return ret;
This warning is generated because 'p->addr' is detected to be not a valid
ftrace location in ftrace_set_filter_ip(). The ftrace address check is done
by check_ftrace_location() at the beginning of check_kprobe_address_safe().
At that point, ftrace_location(addr) == addr should return true if the
module is loaded. Then the module is searched twice:
1. in is_module_text_address(), we find that 'p->addr' is in a module;
2. in __module_text_address(), we find the module;
If the module has just been unloaded before the second search, then
'*probed_mod' is NULL and we would not go to get the module refcount,
then the return value of check_kprobe_address_safe() would be 0, but
actually we need to return -EINVAL.
To fix it, originally we can simply check 'p->addr' is out of text again,
like below. But that would check twice respectively in kernel text and
module text, so finally I reduce them to be once.
if (!(core_kernel_text((unsigned long) p->addr) ||
is_module_text_address((unsigned long) p->addr)) || ...) {
ret = -EINVAL;
goto out;
}
...
*probed_mod = __module_text_address((unsigned long) p->addr);
if (*probed_mod) {
...
} else if (!core_kernel_text((unsigned long) p->addr)) { // check again!
ret = -EINVAL;
goto out;
}
Signed-off-by: Zheng Yejian <zhengyeji...@huawei.com>
---
kernel/kprobes.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)
v2:
- Update commit messages and comments as suggested by Masami.
Link:
https://lore.kernel.org/all/20240408115038.b0c85767bf1f249eccc32...@kernel.org/
v1:
- Link:
https://lore.kernel.org/all/20240407035904.2556645-1-zhengyeji...@huawei.com/
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 9d9095e81792..65adc815fc6e 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1567,10 +1567,17 @@ 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) ||
static_call_text_reserved(p->addr, p->addr) ||
@@ -1580,8 +1587,7 @@ static int check_kprobe_address_safe(struct kprobe *p,
goto out;
}
- /* Check if 'p' is 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
--
2.25.1
