fprobe: Fix to ensure the number of active retprobes is not zero

The number of active retprobes can be zero but it is not acceptable,
so return EINVAL error if detected.

Link: https://lore.kernel.org/all/169750018550.186853.11198884812017796410.stgit@devnote2/
Reported-by: wuqiang.matt <wuqiang.matt@bytedance.com>
Closes: https://lore.kernel.org/all/20231016222103.cb9f426edc60220eabd8aa6a@kernel.org/
Fixes: 5b0ab78998e3 ("fprobe: Add exit_handler support")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index 3b21f40..881f90f 100644 (file)
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -189,7 +189,7 @@ static int fprobe_init_rethook(struct fprobe *fp, int num)
 {
        int i, size;
 
-       if (num < 0)
+       if (num <= 0)
                return -EINVAL;
 
        if (!fp->exit_handler) {
@@ -202,8 +202,8 @@ static int fprobe_init_rethook(struct fprobe *fp, int num)
                size = fp->nr_maxactive;
        else
                size = num * num_possible_cpus() * 2;
-       if (size < 0)
-               return -E2BIG;
+       if (size <= 0)
+               return -EINVAL;
 
        fp->rethook = rethook_alloc((void *)fp, fprobe_exit_handler);
        if (!fp->rethook)