> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 1fd07c10378f..426a1c627508 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
[ ... ]
> +int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog
> *prog)
> +{
> + struct bpf_kprobe_multi_link *link = NULL;
> + struct bpf_link_primer link_primer;
> + struct bpf_kprobe *kprobes = NULL;
> + u32 flags, cnt;
> + u64 __user *ucookies;
> + unsigned long __user *uaddrs;
> + unsigned long __user *usyms;
> + int err, i;
[ ... ]
> + for (i = 0; i < cnt; i++) {
> + unsigned long addr;
> +
> + if (uaddrs) {
> + if (__get_user(addr, uaddrs + i)) {
> + err = -EFAULT;
> + goto error;
> + }
> + } else {
> + unsigned long __user usymbol;
> + char buf[KSYM_NAME_LEN];
> +
> + if (__get_user(usymbol, usyms + i)) {
> + err = -EFAULT;
> + goto error;
> + }
> + err = strncpy_from_user(buf, (const char __user *)
> usymbol, KSYM_NAME_LEN);
> + if (err == KSYM_NAME_LEN)
> + err = -E2BIG;
> + if (err < 0)
> + goto error;
> +
> + addr = kallsyms_lookup_name(buf);
> + if (!addr)
> + goto error;
When kallsyms_lookup_name() returns 0 (symbol not found), is err being set
to an error code before jumping to the error label? It looks like err will
still hold the positive return value from strncpy_from_user() (the string
length), which would be returned to the caller as a success indication.
The error label at the end of the function does:
error:
kvfree(kprobes);
kfree(link);
return err;
This could cause the syscall to return a positive value to userspace instead
of an error, and also leak a prog reference since link_create() only calls
bpf_prog_put() when ret < 0.
> + }
> + if (prog->kprobe_override &&
> !within_error_injection_list(addr)) {
> + err = -EINVAL;
> + goto error;
> + }
[ ... ]
---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
CI run summary: https://github.com/kernel-patches/bpf/actions/runs/20338242683
