kernel/trace/bpf_trace.c:2254:21: sparse: sparse: dereference of noderef expression

kernel/trace/bpf_trace.c:2254:21: sparse: sparse: dereference of noderef expression

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   fbafc3e621c3f4ded43720fdb1d6ce1728ec664e
commit: 0236fec57a15dc2a068dfe4488e0c2ab4559b1ec bpf: Resolve symbols with ftrace_lookup_symbols for kprobe multi link
date:   1 year, 8 months ago
config: i386-randconfig-061-20231101 (https://download.01.org/0day-ci/archive/20231228/202312280124.W09SBhfq-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231228/202312280124.W09SBhfq-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202312280124.W09SBhfq-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> kernel/trace/bpf_trace.c:2254:21: sparse: sparse: dereference of noderef expression
   kernel/trace/bpf_trace.c:2258:66: sparse: sparse: dereference of noderef expression

vim +2254 kernel/trace/bpf_trace.c

  2236	
  2237	static int copy_user_syms(struct user_syms *us, unsigned long __user *usyms, u32 cnt)
  2238	{
  2239		unsigned long __user usymbol;
  2240		const char **syms = NULL;
  2241		char *buf = NULL, *p;
  2242		int err = -ENOMEM;
  2243		unsigned int i;
  2244	
  2245		syms = kvmalloc(cnt * sizeof(*syms), GFP_KERNEL);
  2246		if (!syms)
  2247			goto error;
  2248	
  2249		buf = kvmalloc(cnt * KSYM_NAME_LEN, GFP_KERNEL);
  2250		if (!buf)
  2251			goto error;
  2252	
  2253		for (p = buf, i = 0; i < cnt; i++) {
> 2254			if (__get_user(usymbol, usyms + i)) {
  2255				err = -EFAULT;
  2256				goto error;
  2257			}
  2258			err = strncpy_from_user(p, (const char __user *) usymbol, KSYM_NAME_LEN);
  2259			if (err == KSYM_NAME_LEN)
  2260				err = -E2BIG;
  2261			if (err < 0)
  2262				goto error;
  2263			syms[i] = p;
  2264			p += err + 1;
  2265		}
  2266	
  2267		us->syms = syms;
  2268		us->buf = buf;
  2269		return 0;
  2270	
  2271	error:
  2272		if (err) {
  2273			kvfree(syms);
  2274			kvfree(buf);
  2275		}
  2276		return err;
  2277	}
  2278	

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