Hi Wang, 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: openrisc-randconfig-m031-20221026 compiler: or1k-linux-gcc (GCC) 12.1.0 If you fix the issue, kindly add following tag where applicable | Reported-by: kernel test robot <lkp@xxxxxxxxx> | Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> smatch warnings: kernel/bpf/verifier.c:7021 prepare_func_exit() error: uninitialized symbol 'ret'. vim +/ret +7021 kernel/bpf/verifier.c 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 } Not initialized on else path. 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 } -- 0-DAY CI Kernel Test Service https://01.org/lkp
