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authorMasami Hiramatsu (Google)2023-12-01 14:53:56 +0900
committerMasami Hiramatsu (Google)2023-12-01 14:53:56 +0900
commita1461f1fd6cfdc4b8917c9d4a91e92605d1f28dc (patch)
treecaed8315567be58b912560043e4dde9fe3214940 /include
parentd839a656d0f3caca9f96e9bf912fd394ac6a11bc (diff)
rethook: Use __rcu pointer for rethook::handler
Since the rethook::handler is an RCU-maganged pointer so that it will notice readers the rethook is stopped (unregistered) or not, it should be an __rcu pointer and use appropriate functions to be accessed. This will use appropriate memory barrier when accessing it. OTOH, rethook::data is never changed, so we don't need to check it in get_kretprobe(). NOTE: To avoid sparse warning, rethook::handler is defined by a raw function pointer type with __rcu instead of rethook_handler_t. Link: https://lore.kernel.org/all/170126066201.398836.837498688669005979.stgit@devnote2/ Fixes: 54ecbe6f1ed5 ("rethook: Add a generic return hook") Cc: stable@vger.kernel.org Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202311241808.rv9ceuAh-lkp@intel.com/ Tested-by: JP Kobryn <inwardvessel@gmail.com> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/kprobes.h6
-rw-r--r--include/linux/rethook.h7
2 files changed, 8 insertions, 5 deletions
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 64672bace560..0ff44d6633e3 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -197,10 +197,8 @@ extern int arch_trampoline_kprobe(struct kprobe *p);
#ifdef CONFIG_KRETPROBE_ON_RETHOOK
static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri)
{
- RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(),
- "Kretprobe is accessed from instance under preemptive context");
-
- return (struct kretprobe *)READ_ONCE(ri->node.rethook->data);
+ /* rethook::data is non-changed field, so that you can access it freely. */
+ return (struct kretprobe *)ri->node.rethook->data;
}
static nokprobe_inline unsigned long get_kretprobe_retaddr(struct kretprobe_instance *ri)
{
diff --git a/include/linux/rethook.h b/include/linux/rethook.h
index ce69b2b7bc35..ba60962805f6 100644
--- a/include/linux/rethook.h
+++ b/include/linux/rethook.h
@@ -28,7 +28,12 @@ typedef void (*rethook_handler_t) (struct rethook_node *, void *, unsigned long,
*/
struct rethook {
void *data;
- rethook_handler_t handler;
+ /*
+ * To avoid sparse warnings, this uses a raw function pointer with
+ * __rcu, instead of rethook_handler_t. But this must be same as
+ * rethook_handler_t.
+ */
+ void (__rcu *handler) (struct rethook_node *, void *, unsigned long, struct pt_regs *);
struct objpool_head pool;
struct rcu_head rcu;
};