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Date: Fri, 28 Oct 2022 01:15:43 +0800
From: kernel test robot <lkp@...el.com>
To: Wang Yufen <wangyufen@...wei.com>, bpf@...r.kernel.org,
netdev@...r.kernel.org
Cc: llvm@...ts.linux.dev, oe-kbuild-all@...ts.linux.dev,
ast@...nel.org, daniel@...earbox.net, john.fastabend@...il.com,
andrii@...nel.org, martin.lau@...ux.dev, yhs@...com,
joe@...d.net.nz
Subject: Re: [PATCH net] bpf: Fix memory leaks in __check_func_call
Hi Wang,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on net/master]
url: https://github.com/intel-lab-lkp/linux/commits/Wang-Yufen/bpf-Fix-memory-leaks-in-__check_func_call/20221027-180438
patch link: https://lore.kernel.org/r/1666866213-4394-1-git-send-email-wangyufen%40huawei.com
patch subject: [PATCH net] bpf: Fix memory leaks in __check_func_call
config: i386-randconfig-a013
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/7e03dd8c129a0dbd7c32fb0931ad52e2c9a52f55
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Wang-Yufen/bpf-Fix-memory-leaks-in-__check_func_call/20221027-180438
git checkout 7e03dd8c129a0dbd7c32fb0931ad52e2c9a52f55
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash kernel/bpf/
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@...el.com>
All warnings (new ones prefixed by >>):
>> kernel/bpf/verifier.c:7003:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
if (!callee->in_callback_fn) {
^~~~~~~~~~~~~~~~~~~~~~~
kernel/bpf/verifier.c:7021:9: note: uninitialized use occurs here
return ret;
^~~
kernel/bpf/verifier.c:7003:2: note: remove the 'if' if its condition is always true
if (!callee->in_callback_fn) {
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/bpf/verifier.c:6962:9: note: initialize the variable 'ret' to silence this warning
int ret;
^
= 0
1 warning generated.
vim +7003 kernel/bpf/verifier.c
20571567384428 David Vernet 2022-09-19 6956
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6957 static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx)
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6958 {
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6959 struct bpf_verifier_state *state = env->cur_state;
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6960 struct bpf_func_state *caller, *callee;
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6961 struct bpf_reg_state *r0;
7e03dd8c129a0d Wang Yufen 2022-10-27 6962 int ret;
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6963
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6964 callee = state->frame[state->curframe];
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6965 r0 = &callee->regs[BPF_REG_0];
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6966 if (r0->type == PTR_TO_STACK) {
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6967 /* technically it's ok to return caller's stack pointer
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6968 * (or caller's caller's pointer) back to the caller,
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6969 * since these pointers are valid. Only current stack
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6970 * pointer will be invalid as soon as function exits,
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6971 * but let's be conservative
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6972 */
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6973 verbose(env, "cannot return stack pointer to the caller\n");
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6974 return -EINVAL;
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6975 }
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6976
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6977 state->curframe--;
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6978 caller = state->frame[state->curframe];
69c087ba6225b5 Yonghong Song 2021-02-26 6979 if (callee->in_callback_fn) {
69c087ba6225b5 Yonghong Song 2021-02-26 6980 /* enforce R0 return value range [0, 1]. */
1bfe26fb082724 Dave Marchevsky 2022-09-08 6981 struct tnum range = callee->callback_ret_range;
69c087ba6225b5 Yonghong Song 2021-02-26 6982
69c087ba6225b5 Yonghong Song 2021-02-26 6983 if (r0->type != SCALAR_VALUE) {
69c087ba6225b5 Yonghong Song 2021-02-26 6984 verbose(env, "R0 not a scalar value\n");
7e03dd8c129a0d Wang Yufen 2022-10-27 6985 ret = -EACCES;
7e03dd8c129a0d Wang Yufen 2022-10-27 6986 goto out;
69c087ba6225b5 Yonghong Song 2021-02-26 6987 }
69c087ba6225b5 Yonghong Song 2021-02-26 6988 if (!tnum_in(range, r0->var_off)) {
69c087ba6225b5 Yonghong Song 2021-02-26 6989 verbose_invalid_scalar(env, r0, &range, "callback return", "R0");
7e03dd8c129a0d Wang Yufen 2022-10-27 6990 ret = -EINVAL;
7e03dd8c129a0d Wang Yufen 2022-10-27 6991 goto out;
69c087ba6225b5 Yonghong Song 2021-02-26 6992 }
69c087ba6225b5 Yonghong Song 2021-02-26 6993 } else {
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6994 /* return to the caller whatever r0 had in the callee */
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6995 caller->regs[BPF_REG_0] = *r0;
69c087ba6225b5 Yonghong Song 2021-02-26 6996 }
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 6997
9d9d00ac29d0ef Kumar Kartikeya Dwivedi 2022-08-23 6998 /* callback_fn frame should have released its own additions to parent's
9d9d00ac29d0ef Kumar Kartikeya Dwivedi 2022-08-23 6999 * reference state at this point, or check_reference_leak would
9d9d00ac29d0ef Kumar Kartikeya Dwivedi 2022-08-23 7000 * complain, hence it must be the same as the caller. There is no need
9d9d00ac29d0ef Kumar Kartikeya Dwivedi 2022-08-23 7001 * to copy it back.
9d9d00ac29d0ef Kumar Kartikeya Dwivedi 2022-08-23 7002 */
9d9d00ac29d0ef Kumar Kartikeya Dwivedi 2022-08-23 @7003 if (!callee->in_callback_fn) {
fd978bf7fd3125 Joe Stringer 2018-10-02 7004 /* Transfer references to the caller */
7e03dd8c129a0d Wang Yufen 2022-10-27 7005 ret = copy_reference_state(caller, callee);
7e03dd8c129a0d Wang Yufen 2022-10-27 7006 if (ret)
7e03dd8c129a0d Wang Yufen 2022-10-27 7007 goto out;
9d9d00ac29d0ef Kumar Kartikeya Dwivedi 2022-08-23 7008 }
fd978bf7fd3125 Joe Stringer 2018-10-02 7009
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 7010 *insn_idx = callee->callsite + 1;
06ee7115b0d174 Alexei Starovoitov 2019-04-01 7011 if (env->log.level & BPF_LOG_LEVEL) {
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 7012 verbose(env, "returning from callee:\n");
0f55f9ed21f966 Christy Lee 2021-12-16 7013 print_verifier_state(env, callee, true);
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 7014 verbose(env, "to caller at %d:\n", *insn_idx);
0f55f9ed21f966 Christy Lee 2021-12-16 7015 print_verifier_state(env, caller, true);
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 7016 }
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 7017 /* clear everything in the callee */
7e03dd8c129a0d Wang Yufen 2022-10-27 7018 out:
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 7019 free_func_state(callee);
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 7020 state->frame[state->curframe + 1] = NULL;
7e03dd8c129a0d Wang Yufen 2022-10-27 7021 return ret;
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 7022 }
f4d7e40a5b7157 Alexei Starovoitov 2017-12-14 7023
--
0-DAY CI Kernel Test Service
https://01.org/lkp
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