* [PATCH bpf v3] bpf: Fix memory leaks in __check_func_call
@ 2022-11-03 9:42 Wang Yufen
2022-11-08 0:46 ` Martin KaFai Lau
0 siblings, 1 reply; 3+ messages in thread
From: Wang Yufen @ 2022-11-03 9:42 UTC (permalink / raw)
To: bpf, netdev; +Cc: ast, daniel, john.fastabend, andrii, martin.lau, yhs, joe
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);
+ 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");
--
1.8.3.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH bpf v3] bpf: Fix memory leaks in __check_func_call
2022-11-03 9:42 [PATCH bpf v3] bpf: Fix memory leaks in __check_func_call Wang Yufen
@ 2022-11-08 0:46 ` Martin KaFai Lau
2022-11-08 3:32 ` wangyufen
0 siblings, 1 reply; 3+ messages in thread
From: Martin KaFai Lau @ 2022-11-08 0:46 UTC (permalink / raw)
To: Wang Yufen, bpf, netdev; +Cc: ast, daniel, john.fastabend, andrii, yhs, joe
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");
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH bpf v3] bpf: Fix memory leaks in __check_func_call
2022-11-08 0:46 ` Martin KaFai Lau
@ 2022-11-08 3:32 ` wangyufen
0 siblings, 0 replies; 3+ messages in thread
From: wangyufen @ 2022-11-08 3:32 UTC (permalink / raw)
To: Martin KaFai Lau, bpf, netdev
Cc: ast, daniel, john.fastabend, andrii, yhs, joe
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");
>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2022-11-08 3:33 UTC | newest]
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2022-11-03 9:42 [PATCH bpf v3] bpf: Fix memory leaks in __check_func_call Wang Yufen
2022-11-08 0:46 ` Martin KaFai Lau
2022-11-08 3:32 ` wangyufen
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