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tracing/fprobe: Remove fprobe from hash in failure path

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When register_fprobe_ips() fails, it tries to remove a list of
fprobe_hash_node from fprobe_ip_table, but it missed to remove
fprobe itself from fprobe_table. Moreover, when removing
the fprobe_hash_node which is added to rhltable once, it must
use kfree_rcu() after removing from rhltable.

To fix these issues, this reuses unregister_fprobe() internal
code to rollback the half-way registered fprobe.

Link: https://lore.kernel.org/all/177669366417.132053.17874946321744910456.stgit@mhiramat.tok.corp.google.com/

Fixes: 4346ba1604 ("fprobe: Rewrite fprobe on function-graph tracer")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
This commit is contained in:
Masami Hiramatsu (Google) 2026-04-20 23:01:04 +09:00
parent 1aec9e5c3e
commit 845947aca6
1 changed files with 48 additions and 44 deletions
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92
kernel/trace/fprobe.c
View File

@ -79,20 +79,27 @@ static const struct rhashtable_params fprobe_rht_params = {
};
/* Node insertion and deletion requires the fprobe_mutex */
static int insert_fprobe_node(struct fprobe_hlist_node *node)
static int insert_fprobe_node(struct fprobe_hlist_node *node, struct fprobe *fp)
{
int ret;
lockdep_assert_held(&fprobe_mutex);
return rhltable_insert(&fprobe_ip_table, &node->hlist, fprobe_rht_params);
ret = rhltable_insert(&fprobe_ip_table, &node->hlist, fprobe_rht_params);
/* Set the fprobe pointer if insertion was successful. */
if (!ret)
WRITE_ONCE(node->fp, fp);
return ret;
}
/* Return true if there are synonims */
static bool delete_fprobe_node(struct fprobe_hlist_node *node)
{
lockdep_assert_held(&fprobe_mutex);
bool ret;
/* Avoid double deleting */
lockdep_assert_held(&fprobe_mutex);
/* Avoid double deleting and non-inserted nodes */
if (READ_ONCE(node->fp) != NULL) {
WRITE_ONCE(node->fp, NULL);
rhltable_remove(&fprobe_ip_table, &node->hlist,
@ -756,7 +763,6 @@ static int fprobe_init(struct fprobe *fp, unsigned long *addrs, int num)
fp->hlist_array = hlist_array;
hlist_array->fp = fp;
for (i = 0; i < num; i++) {
hlist_array->array[i].fp = fp;
addr = ftrace_location(addrs[i]);
if (!addr) {
fprobe_fail_cleanup(fp);
@ -820,6 +826,8 @@ int register_fprobe(struct fprobe *fp, const char *filter, const char *notfilter
}
EXPORT_SYMBOL_GPL(register_fprobe);
static int unregister_fprobe_nolock(struct fprobe *fp);
/**
* register_fprobe_ips() - Register fprobe to ftrace by address.
* @fp: A fprobe data structure to be registered.
@ -846,28 +854,25 @@ int register_fprobe_ips(struct fprobe *fp, unsigned long *addrs, int num)
if (ret)
return ret;
hlist_array = fp->hlist_array;
if (fprobe_is_ftrace(fp))
ret = fprobe_ftrace_add_ips(addrs, num);
else
ret = fprobe_graph_add_ips(addrs, num);
if (!ret) {
add_fprobe_hash(fp);
for (i = 0; i < hlist_array->size; i++) {
ret = insert_fprobe_node(&hlist_array->array[i]);
if (ret)
break;
}
/* fallback on insert error */
if (ret) {
for (i--; i >= 0; i--)
delete_fprobe_node(&hlist_array->array[i]);
}
if (ret) {
fprobe_fail_cleanup(fp);
return ret;
}
if (ret)
fprobe_fail_cleanup(fp);
hlist_array = fp->hlist_array;
ret = add_fprobe_hash(fp);
for (i = 0; i < hlist_array->size && !ret; i++)
ret = insert_fprobe_node(&hlist_array->array[i], fp);
if (ret) {
unregister_fprobe_nolock(fp);
/* In error case, wait for clean up safely. */
synchronize_rcu();
}
return ret;
}
@ -911,27 +916,12 @@ bool fprobe_is_registered(struct fprobe *fp)
return true;
}
/**
* unregister_fprobe() - Unregister fprobe.
* @fp: A fprobe data structure to be unregistered.
*
* Unregister fprobe (and remove ftrace hooks from the function entries).
*
* Return 0 if @fp is unregistered successfully, -errno if not.
*/
int unregister_fprobe(struct fprobe *fp)
static int unregister_fprobe_nolock(struct fprobe *fp)
{
struct fprobe_hlist *hlist_array;
struct fprobe_hlist *hlist_array = fp->hlist_array;
unsigned long *addrs = NULL;
int ret = 0, i, count;
int i, count;
mutex_lock(&fprobe_mutex);
if (!fp || !fprobe_registered(fp)) {
ret = -EINVAL;
goto out;
}
hlist_array = fp->hlist_array;
addrs = kcalloc(hlist_array->size, sizeof(unsigned long), GFP_KERNEL);
/*
* This will remove fprobe_hash_node from the hash table even if
@ -957,12 +947,26 @@ int unregister_fprobe(struct fprobe *fp)
kfree_rcu(hlist_array, rcu);
fp->hlist_array = NULL;
out:
mutex_unlock(&fprobe_mutex);
kfree(addrs);
return ret;
return 0;
}
/**
* unregister_fprobe() - Unregister fprobe.
* @fp: A fprobe data structure to be unregistered.
*
* Unregister fprobe (and remove ftrace hooks from the function entries).
*
* Return 0 if @fp is unregistered successfully, -errno if not.
*/
int unregister_fprobe(struct fprobe *fp)
{
guard(mutex)(&fprobe_mutex);
if (!fp || !fprobe_registered(fp))
return -EINVAL;
return unregister_fprobe_nolock(fp);
}
EXPORT_SYMBOL_GPL(unregister_fprobe);