* Re: [PATCH bpf-next] kallsyms: Disable preemption for find_kallsyms_symbol_value
2023-04-03 22:02 [PATCH bpf-next] kallsyms: Disable preemption for find_kallsyms_symbol_value Jiri Olsa
@ 2023-04-04 1:43 ` Leizhen (ThunderTown)
2023-04-04 6:56 ` Artem Savkov
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Leizhen (ThunderTown) @ 2023-04-04 1:43 UTC (permalink / raw)
To: Jiri Olsa, Luis Chamberlain, Alexei Starovoitov, Daniel Borkmann,
Andrii Nakryiko
Cc: Artem Savkov, bpf, linux-modules, linux-kernel, Martin KaFai Lau,
Song Liu, Yonghong Song, John Fastabend, KP Singh,
Stanislav Fomichev, Hao Luo, Petr Mladek, Viktor Malik
On 2023/4/4 6:02, Jiri Olsa wrote:
> Artem reported suspicious RCU usage [1]. The reason is that verifier
> calls find_kallsyms_symbol_value with preemption enabled which will
> trigger suspicious RCU usage warning in rcu_dereference_sched call.
>
> Disabling preemption in find_kallsyms_symbol_value and adding
> __find_kallsyms_symbol_value function.
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
>
> Fixes: 31bf1dbccfb0 ("bpf: Fix attaching fentry/fexit/fmod_ret/lsm to modules")
> [1] https://lore.kernel.org/bpf/ZBrPMkv8YVRiWwCR@samus.usersys.redhat.com/
> Reported-by: Artem Savkov <asavkov@redhat.com>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
> kernel/module/kallsyms.c | 16 +++++++++++++---
> 1 file changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
> index ab2376a1be88..bdc911dbcde5 100644
> --- a/kernel/module/kallsyms.c
> +++ b/kernel/module/kallsyms.c
> @@ -442,7 +442,7 @@ int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
> }
>
> /* Given a module and name of symbol, find and return the symbol's value */
> -unsigned long find_kallsyms_symbol_value(struct module *mod, const char *name)
> +static unsigned long __find_kallsyms_symbol_value(struct module *mod, const char *name)
> {
> unsigned int i;
> struct mod_kallsyms *kallsyms = rcu_dereference_sched(mod->kallsyms);
> @@ -466,7 +466,7 @@ static unsigned long __module_kallsyms_lookup_name(const char *name)
> if (colon) {
> mod = find_module_all(name, colon - name, false);
> if (mod)
> - return find_kallsyms_symbol_value(mod, colon + 1);
> + return __find_kallsyms_symbol_value(mod, colon + 1);
> return 0;
> }
>
> @@ -475,7 +475,7 @@ static unsigned long __module_kallsyms_lookup_name(const char *name)
>
> if (mod->state == MODULE_STATE_UNFORMED)
> continue;
> - ret = find_kallsyms_symbol_value(mod, name);
> + ret = __find_kallsyms_symbol_value(mod, name);
> if (ret)
> return ret;
> }
> @@ -494,6 +494,16 @@ unsigned long module_kallsyms_lookup_name(const char *name)
> return ret;
> }
>
> +unsigned long find_kallsyms_symbol_value(struct module *mod, const char *name)
> +{
> + unsigned long ret;
> +
> + preempt_disable();
> + ret = __find_kallsyms_symbol_value(mod, name);
> + preempt_enable();
> + return ret;
> +}
> +
> int module_kallsyms_on_each_symbol(const char *modname,
> int (*fn)(void *, const char *,
> struct module *, unsigned long),
>
--
Regards,
Zhen Lei
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH bpf-next] kallsyms: Disable preemption for find_kallsyms_symbol_value
2023-04-03 22:02 [PATCH bpf-next] kallsyms: Disable preemption for find_kallsyms_symbol_value Jiri Olsa
2023-04-04 1:43 ` Leizhen (ThunderTown)
@ 2023-04-04 6:56 ` Artem Savkov
2023-04-05 0:20 ` patchwork-bot+netdevbpf
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Artem Savkov @ 2023-04-04 6:56 UTC (permalink / raw)
To: Jiri Olsa
Cc: Luis Chamberlain, Alexei Starovoitov, Daniel Borkmann,
Andrii Nakryiko, bpf, linux-modules, linux-kernel,
Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
KP Singh, Stanislav Fomichev, Hao Luo, Petr Mladek,
Leizhen (ThunderTown), Viktor Malik
On Tue, Apr 04, 2023 at 12:02:54AM +0200, Jiri Olsa wrote:
> Artem reported suspicious RCU usage [1]. The reason is that verifier
> calls find_kallsyms_symbol_value with preemption enabled which will
> trigger suspicious RCU usage warning in rcu_dereference_sched call.
>
> Disabling preemption in find_kallsyms_symbol_value and adding
> __find_kallsyms_symbol_value function.
Tested-by: Artem Savkov <asavkov@redhat.com>
> Fixes: 31bf1dbccfb0 ("bpf: Fix attaching fentry/fexit/fmod_ret/lsm to modules")
> [1] https://lore.kernel.org/bpf/ZBrPMkv8YVRiWwCR@samus.usersys.redhat.com/
> Reported-by: Artem Savkov <asavkov@redhat.com>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
> kernel/module/kallsyms.c | 16 +++++++++++++---
> 1 file changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
> index ab2376a1be88..bdc911dbcde5 100644
> --- a/kernel/module/kallsyms.c
> +++ b/kernel/module/kallsyms.c
> @@ -442,7 +442,7 @@ int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
> }
>
> /* Given a module and name of symbol, find and return the symbol's value */
> -unsigned long find_kallsyms_symbol_value(struct module *mod, const char *name)
> +static unsigned long __find_kallsyms_symbol_value(struct module *mod, const char *name)
> {
> unsigned int i;
> struct mod_kallsyms *kallsyms = rcu_dereference_sched(mod->kallsyms);
> @@ -466,7 +466,7 @@ static unsigned long __module_kallsyms_lookup_name(const char *name)
> if (colon) {
> mod = find_module_all(name, colon - name, false);
> if (mod)
> - return find_kallsyms_symbol_value(mod, colon + 1);
> + return __find_kallsyms_symbol_value(mod, colon + 1);
> return 0;
> }
>
> @@ -475,7 +475,7 @@ static unsigned long __module_kallsyms_lookup_name(const char *name)
>
> if (mod->state == MODULE_STATE_UNFORMED)
> continue;
> - ret = find_kallsyms_symbol_value(mod, name);
> + ret = __find_kallsyms_symbol_value(mod, name);
> if (ret)
> return ret;
> }
> @@ -494,6 +494,16 @@ unsigned long module_kallsyms_lookup_name(const char *name)
> return ret;
> }
>
> +unsigned long find_kallsyms_symbol_value(struct module *mod, const char *name)
> +{
> + unsigned long ret;
> +
> + preempt_disable();
> + ret = __find_kallsyms_symbol_value(mod, name);
> + preempt_enable();
> + return ret;
> +}
> +
> int module_kallsyms_on_each_symbol(const char *modname,
> int (*fn)(void *, const char *,
> struct module *, unsigned long),
> --
> 2.39.2
>
--
Artem
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH bpf-next] kallsyms: Disable preemption for find_kallsyms_symbol_value
2023-04-03 22:02 [PATCH bpf-next] kallsyms: Disable preemption for find_kallsyms_symbol_value Jiri Olsa
2023-04-04 1:43 ` Leizhen (ThunderTown)
2023-04-04 6:56 ` Artem Savkov
@ 2023-04-05 0:20 ` patchwork-bot+netdevbpf
2023-04-06 14:47 ` Petr Mladek
2023-04-06 14:56 ` Aaron Tomlin
4 siblings, 0 replies; 6+ messages in thread
From: patchwork-bot+netdevbpf @ 2023-04-05 0:20 UTC (permalink / raw)
To: Jiri Olsa
Cc: mcgrof, ast, daniel, andrii, asavkov, bpf, linux-modules,
linux-kernel, kafai, songliubraving, yhs, john.fastabend, kpsingh,
sdf, haoluo, pmladek, thunder.leizhen, vmalik
Hello:
This patch was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <andrii@kernel.org>:
On Tue, 4 Apr 2023 00:02:54 +0200 you wrote:
> Artem reported suspicious RCU usage [1]. The reason is that verifier
> calls find_kallsyms_symbol_value with preemption enabled which will
> trigger suspicious RCU usage warning in rcu_dereference_sched call.
>
> Disabling preemption in find_kallsyms_symbol_value and adding
> __find_kallsyms_symbol_value function.
>
> [...]
Here is the summary with links:
- [bpf-next] kallsyms: Disable preemption for find_kallsyms_symbol_value
https://git.kernel.org/bpf/bpf-next/c/d099f594ad56
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH bpf-next] kallsyms: Disable preemption for find_kallsyms_symbol_value
2023-04-03 22:02 [PATCH bpf-next] kallsyms: Disable preemption for find_kallsyms_symbol_value Jiri Olsa
` (2 preceding siblings ...)
2023-04-05 0:20 ` patchwork-bot+netdevbpf
@ 2023-04-06 14:47 ` Petr Mladek
2023-04-06 14:56 ` Aaron Tomlin
4 siblings, 0 replies; 6+ messages in thread
From: Petr Mladek @ 2023-04-06 14:47 UTC (permalink / raw)
To: Jiri Olsa
Cc: Luis Chamberlain, Alexei Starovoitov, Daniel Borkmann,
Andrii Nakryiko, Artem Savkov, bpf, linux-modules, linux-kernel,
Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
KP Singh, Stanislav Fomichev, Hao Luo, Leizhen (ThunderTown),
Viktor Malik
On Tue 2023-04-04 00:02:54, Jiri Olsa wrote:
> Artem reported suspicious RCU usage [1]. The reason is that verifier
> calls find_kallsyms_symbol_value with preemption enabled which will
> trigger suspicious RCU usage warning in rcu_dereference_sched call.
>
> Disabling preemption in find_kallsyms_symbol_value and adding
> __find_kallsyms_symbol_value function.
>
> Fixes: 31bf1dbccfb0 ("bpf: Fix attaching fentry/fexit/fmod_ret/lsm to modules")
> [1] https://lore.kernel.org/bpf/ZBrPMkv8YVRiWwCR@samus.usersys.redhat.com/
> Reported-by: Artem Savkov <asavkov@redhat.com>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Just for record:
Reviewed-by: Petr Mladek <pmladek@suse.com>
Best Regards,
Petr
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH bpf-next] kallsyms: Disable preemption for find_kallsyms_symbol_value
2023-04-03 22:02 [PATCH bpf-next] kallsyms: Disable preemption for find_kallsyms_symbol_value Jiri Olsa
` (3 preceding siblings ...)
2023-04-06 14:47 ` Petr Mladek
@ 2023-04-06 14:56 ` Aaron Tomlin
4 siblings, 0 replies; 6+ messages in thread
From: Aaron Tomlin @ 2023-04-06 14:56 UTC (permalink / raw)
To: Jiri Olsa
Cc: Luis Chamberlain, Alexei Starovoitov, Daniel Borkmann,
Andrii Nakryiko, Artem Savkov, bpf, linux-modules, linux-kernel,
Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
KP Singh, Stanislav Fomichev, Hao Luo, Petr Mladek,
Leizhen (ThunderTown), Viktor Malik
On Tue, Apr 04, 2023 at 12:02:54AM +0200, Jiri Olsa wrote:
> Artem reported suspicious RCU usage [1]. The reason is that verifier
> calls find_kallsyms_symbol_value with preemption enabled which will
> trigger suspicious RCU usage warning in rcu_dereference_sched call.
>
> Disabling preemption in find_kallsyms_symbol_value and adding
> __find_kallsyms_symbol_value function.
>
> Fixes: 31bf1dbccfb0 ("bpf: Fix attaching fentry/fexit/fmod_ret/lsm to modules")
> [1] https://lore.kernel.org/bpf/ZBrPMkv8YVRiWwCR@samus.usersys.redhat.com/
> Reported-by: Artem Savkov <asavkov@redhat.com>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
> kernel/module/kallsyms.c | 16 +++++++++++++---
> 1 file changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
> index ab2376a1be88..bdc911dbcde5 100644
> --- a/kernel/module/kallsyms.c
> +++ b/kernel/module/kallsyms.c
> @@ -442,7 +442,7 @@ int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
> }
>
> /* Given a module and name of symbol, find and return the symbol's value */
> -unsigned long find_kallsyms_symbol_value(struct module *mod, const char *name)
> +static unsigned long __find_kallsyms_symbol_value(struct module *mod, const char *name)
> {
> unsigned int i;
> struct mod_kallsyms *kallsyms = rcu_dereference_sched(mod->kallsyms);
> @@ -466,7 +466,7 @@ static unsigned long __module_kallsyms_lookup_name(const char *name)
> if (colon) {
> mod = find_module_all(name, colon - name, false);
> if (mod)
> - return find_kallsyms_symbol_value(mod, colon + 1);
> + return __find_kallsyms_symbol_value(mod, colon + 1);
> return 0;
> }
>
> @@ -475,7 +475,7 @@ static unsigned long __module_kallsyms_lookup_name(const char *name)
>
> if (mod->state == MODULE_STATE_UNFORMED)
> continue;
> - ret = find_kallsyms_symbol_value(mod, name);
> + ret = __find_kallsyms_symbol_value(mod, name);
> if (ret)
> return ret;
> }
> @@ -494,6 +494,16 @@ unsigned long module_kallsyms_lookup_name(const char *name)
> return ret;
> }
>
> +unsigned long find_kallsyms_symbol_value(struct module *mod, const char *name)
> +{
> + unsigned long ret;
> +
> + preempt_disable();
> + ret = __find_kallsyms_symbol_value(mod, name);
> + preempt_enable();
> + return ret;
> +}
> +
> int module_kallsyms_on_each_symbol(const char *modname,
> int (*fn)(void *, const char *,
> struct module *, unsigned long),
> --
> 2.39.2
>
Reviewed-by: Aaron Tomlin <atomlin@atomlin.com>
--
Aaron Tomlin
^ permalink raw reply [flat|nested] 6+ messages in thread