| Message ID | 1667468524-4926-1-git-send-email-wangyufen@huawei.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | BPF |
| Headers | show |
| Series | [bpf,v3] bpf: Fix memory leaks in __check_func_call | expand |
On 11/3/22 2:42 AM, Wang Yufen wrote: > kmemleak reports this issue: > > unreferenced object 0xffff88817139d000 (size 2048): > comm "test_progs", pid 33246, jiffies 4307381979 (age 45851.820s) > hex dump (first 32 bytes): > 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > backtrace: > [<0000000045f075f0>] kmalloc_trace+0x27/0xa0 > [<0000000098b7c90a>] __check_func_call+0x316/0x1230 > [<00000000b4c3c403>] check_helper_call+0x172e/0x4700 > [<00000000aa3875b7>] do_check+0x21d8/0x45e0 > [<000000001147357b>] do_check_common+0x767/0xaf0 > [<00000000b5a595b4>] bpf_check+0x43e3/0x5bc0 > [<0000000011e391b1>] bpf_prog_load+0xf26/0x1940 > [<0000000007f765c0>] __sys_bpf+0xd2c/0x3650 > [<00000000839815d6>] __x64_sys_bpf+0x75/0xc0 > [<00000000946ee250>] do_syscall_64+0x3b/0x90 > [<0000000000506b7f>] entry_SYSCALL_64_after_hwframe+0x63/0xcd > > The root case here is: In function prepare_func_exit(), the callee is > not released in the abnormal scenario after "state->curframe--;". To > fix, move "state->curframe--;" to the very bottom of the function, > right when we free callee and reset frame[] pointer to NULL, as Andrii > suggested. > > In addition, function __check_func_call() has a similar problem. In > the abnormal scenario before "state->curframe++;", the callee is alse > not released. > > Fixes: 69c087ba6225 ("bpf: Add bpf_for_each_map_elem() helper") > Fixes: fd978bf7fd31 ("bpf: Add reference tracking to verifier") > Signed-off-by: Wang Yufen <wangyufen@huawei.com> > --- > kernel/bpf/verifier.c | 13 +++++++++---- > 1 file changed, 9 insertions(+), 4 deletions(-) > > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > index 7f0a9f6..eff7a5a 100644 > --- a/kernel/bpf/verifier.c > +++ b/kernel/bpf/verifier.c > @@ -6736,11 +6736,11 @@ static int __check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn > /* Transfer references to the callee */ > err = copy_reference_state(callee, caller); > if (err) > - return err; > + goto err_out; > > err = set_callee_state_cb(env, caller, callee, *insn_idx); > if (err) > - return err; > + goto err_out; > > clear_caller_saved_regs(env, caller->regs); > > @@ -6757,6 +6757,11 @@ static int __check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn > print_verifier_state(env, callee, true); > } > return 0; > + > +err_out: > + kfree(callee); Is it sure that free_func_state() is not needed ? > + state->frame[state->curframe + 1] = NULL; > + return err; > } > > int map_set_for_each_callback_args(struct bpf_verifier_env *env, > @@ -6970,8 +6975,7 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) > return -EINVAL; > } > > - state->curframe--; > - caller = state->frame[state->curframe]; > + caller = state->frame[state->curframe - 1]; > if (callee->in_callback_fn) { > /* enforce R0 return value range [0, 1]. */ > struct tnum range = callee->callback_ret_range; > @@ -7001,6 +7005,7 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) > return err; > } > > + state->curframe--; nit. state->curframe is always pointing to callee upto this point? Instead of doing another +1 dance in the latter 'state->frame[state->curframe + 1] = NULL;', how about do it later like: /* clear everything in the callee */ free_func_state(callee); state->frame[state->curframe--] = NULL; It shouldn't affect the earlier print_verifier_state() which explicitly takes callee and caller as its arg, right? > *insn_idx = callee->callsite + 1; > if (env->log.level & BPF_LOG_LEVEL) { > verbose(env, "returning from callee:\n");
在 2022/11/8 8:46, Martin KaFai Lau 写道: > On 11/3/22 2:42 AM, Wang Yufen wrote: >> kmemleak reports this issue: >> >> unreferenced object 0xffff88817139d000 (size 2048): >> comm "test_progs", pid 33246, jiffies 4307381979 (age 45851.820s) >> hex dump (first 32 bytes): >> 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ >> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ >> backtrace: >> [<0000000045f075f0>] kmalloc_trace+0x27/0xa0 >> [<0000000098b7c90a>] __check_func_call+0x316/0x1230 >> [<00000000b4c3c403>] check_helper_call+0x172e/0x4700 >> [<00000000aa3875b7>] do_check+0x21d8/0x45e0 >> [<000000001147357b>] do_check_common+0x767/0xaf0 >> [<00000000b5a595b4>] bpf_check+0x43e3/0x5bc0 >> [<0000000011e391b1>] bpf_prog_load+0xf26/0x1940 >> [<0000000007f765c0>] __sys_bpf+0xd2c/0x3650 >> [<00000000839815d6>] __x64_sys_bpf+0x75/0xc0 >> [<00000000946ee250>] do_syscall_64+0x3b/0x90 >> [<0000000000506b7f>] entry_SYSCALL_64_after_hwframe+0x63/0xcd >> >> The root case here is: In function prepare_func_exit(), the callee is >> not released in the abnormal scenario after "state->curframe--;". To >> fix, move "state->curframe--;" to the very bottom of the function, >> right when we free callee and reset frame[] pointer to NULL, as Andrii >> suggested. >> >> In addition, function __check_func_call() has a similar problem. In >> the abnormal scenario before "state->curframe++;", the callee is alse >> not released. >> >> Fixes: 69c087ba6225 ("bpf: Add bpf_for_each_map_elem() helper") >> Fixes: fd978bf7fd31 ("bpf: Add reference tracking to verifier") >> Signed-off-by: Wang Yufen <wangyufen@huawei.com> >> --- >> kernel/bpf/verifier.c | 13 +++++++++---- >> 1 file changed, 9 insertions(+), 4 deletions(-) >> >> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c >> index 7f0a9f6..eff7a5a 100644 >> --- a/kernel/bpf/verifier.c >> +++ b/kernel/bpf/verifier.c >> @@ -6736,11 +6736,11 @@ static int __check_func_call(struct >> bpf_verifier_env *env, struct bpf_insn *insn >> /* Transfer references to the callee */ >> err = copy_reference_state(callee, caller); >> if (err) >> - return err; >> + goto err_out; >> err = set_callee_state_cb(env, caller, callee, *insn_idx); >> if (err) >> - return err; >> + goto err_out; >> clear_caller_saved_regs(env, caller->regs); >> @@ -6757,6 +6757,11 @@ static int __check_func_call(struct >> bpf_verifier_env *env, struct bpf_insn *insn >> print_verifier_state(env, callee, true); >> } >> return 0; >> + >> +err_out: >> + kfree(callee); > > Is it sure that free_func_state() is not needed ? No, free_func_state() is needed. Sorry, I didn't notice that memory is alloced for callee->refs in copy_reference_state()-> copy_array() -> kmalloc_track_caller(). will change in v4 Thanks. Wang > >> + state->frame[state->curframe + 1] = NULL; >> + return err; >> } >> int map_set_for_each_callback_args(struct bpf_verifier_env *env, >> @@ -6970,8 +6975,7 @@ static int prepare_func_exit(struct >> bpf_verifier_env *env, int *insn_idx) >> return -EINVAL; >> } >> - state->curframe--; >> - caller = state->frame[state->curframe]; >> + caller = state->frame[state->curframe - 1]; >> if (callee->in_callback_fn) { >> /* enforce R0 return value range [0, 1]. */ >> struct tnum range = callee->callback_ret_range; >> @@ -7001,6 +7005,7 @@ static int prepare_func_exit(struct >> bpf_verifier_env *env, int *insn_idx) >> return err; >> } >> + state->curframe--; > > nit. state->curframe is always pointing to callee upto this point? > Instead of doing another +1 dance in the latter > 'state->frame[state->curframe + 1] = NULL;', how about do it later like: > > /* clear everything in the callee */ > free_func_state(callee); > state->frame[state->curframe--] = NULL; > > > It shouldn't affect the earlier print_verifier_state() which > explicitly takes callee and caller as its arg, right? Yes, state->curframe not affect print_verifier_state(), doing "state->curframe--" at the end of the function is better, also will change in v4. Thanks! > >> *insn_idx = callee->callsite + 1; >> if (env->log.level & BPF_LOG_LEVEL) { >> verbose(env, "returning from callee:\n"); >
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 7f0a9f6..eff7a5a 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6736,11 +6736,11 @@ static int __check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn /* Transfer references to the callee */ err = copy_reference_state(callee, caller); if (err) - return err; + goto err_out; err = set_callee_state_cb(env, caller, callee, *insn_idx); if (err) - return err; + goto err_out; clear_caller_saved_regs(env, caller->regs); @@ -6757,6 +6757,11 @@ static int __check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn print_verifier_state(env, callee, true); } return 0; + +err_out: + kfree(callee); + state->frame[state->curframe + 1] = NULL; + return err; } int map_set_for_each_callback_args(struct bpf_verifier_env *env, @@ -6970,8 +6975,7 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) return -EINVAL; } - state->curframe--; - caller = state->frame[state->curframe]; + caller = state->frame[state->curframe - 1]; if (callee->in_callback_fn) { /* enforce R0 return value range [0, 1]. */ struct tnum range = callee->callback_ret_range; @@ -7001,6 +7005,7 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) return err; } + state->curframe--; *insn_idx = callee->callsite + 1; if (env->log.level & BPF_LOG_LEVEL) { verbose(env, "returning from callee:\n");
kmemleak reports this issue: unreferenced object 0xffff88817139d000 (size 2048): comm "test_progs", pid 33246, jiffies 4307381979 (age 45851.820s) hex dump (first 32 bytes): 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<0000000045f075f0>] kmalloc_trace+0x27/0xa0 [<0000000098b7c90a>] __check_func_call+0x316/0x1230 [<00000000b4c3c403>] check_helper_call+0x172e/0x4700 [<00000000aa3875b7>] do_check+0x21d8/0x45e0 [<000000001147357b>] do_check_common+0x767/0xaf0 [<00000000b5a595b4>] bpf_check+0x43e3/0x5bc0 [<0000000011e391b1>] bpf_prog_load+0xf26/0x1940 [<0000000007f765c0>] __sys_bpf+0xd2c/0x3650 [<00000000839815d6>] __x64_sys_bpf+0x75/0xc0 [<00000000946ee250>] do_syscall_64+0x3b/0x90 [<0000000000506b7f>] entry_SYSCALL_64_after_hwframe+0x63/0xcd The root case here is: In function prepare_func_exit(), the callee is not released in the abnormal scenario after "state->curframe--;". To fix, move "state->curframe--;" to the very bottom of the function, right when we free callee and reset frame[] pointer to NULL, as Andrii suggested. In addition, function __check_func_call() has a similar problem. In the abnormal scenario before "state->curframe++;", the callee is alse not released. Fixes: 69c087ba6225 ("bpf: Add bpf_for_each_map_elem() helper") Fixes: fd978bf7fd31 ("bpf: Add reference tracking to verifier") Signed-off-by: Wang Yufen <wangyufen@huawei.com> --- kernel/bpf/verifier.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)