bpf: Improve verifier log for resource leak on exit

jeromemarchand · jeromemarchand · commit a2b049bf0f7a · 2025-06-17T13:44:02.000+02:00
JIRA: https://issues.redhat.com/browse/RHEL-78201 commit cbd8730 Author: Kumar Kartikeya Dwivedi <memxor@gmail.com> Date: Tue Dec 3 19:03:58 2024 -0800 bpf: Improve verifier log for resource leak on exit The verifier log when leaking resources on BPF_EXIT may be a bit confusing, as it's a problem only when finally existing from the main prog, not from any of the subprogs. Hence, update the verifier error string and the corresponding selftests matching on it. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Suggested-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Link: https://lore.kernel.org/r/20241204030400.208005-6-memxor@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
@@ -19098,7 +19098,7 @@ static int do_check(struct bpf_verifier_env *env)
 				 * match caller reference state when it exits.
 				 */
 				err = check_resource_leak(env, exception_exit, !env->cur_state->curframe,
-							  "BPF_EXIT instruction");
+							  "BPF_EXIT instruction in main prog");
 				if (err)
 					return err;
 
diff --git a/tools/testing/selftests/bpf/progs/exceptions_fail.c b/tools/testing/selftests/bpf/progs/exceptions_fail.c
@@ -131,7 +131,7 @@ int reject_subprog_with_lock(void *ctx)
 }
 
 SEC("?tc")
-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_rcu_read_lock-ed region")
+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_rcu_read_lock-ed region")
 int reject_with_rcu_read_lock(void *ctx)
 {
 	bpf_rcu_read_lock();
@@ -147,7 +147,7 @@ __noinline static int throwing_subprog(struct __sk_buff *ctx)
 }
 
 SEC("?tc")
-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_rcu_read_lock-ed region")
+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_rcu_read_lock-ed region")
 int reject_subprog_with_rcu_read_lock(void *ctx)
 {
 	bpf_rcu_read_lock();
diff --git a/tools/testing/selftests/bpf/progs/preempt_lock.c b/tools/testing/selftests/bpf/progs/preempt_lock.c
@@ -6,15 +6,15 @@
 #include "bpf_experimental.h"
 
 SEC("?tc")
-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_preempt_disable-ed region")
+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_preempt_disable-ed region")
 int preempt_lock_missing_1(struct __sk_buff *ctx)
 {
 	bpf_preempt_disable();
 	return 0;
 }
 
 SEC("?tc")
-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_preempt_disable-ed region")
+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_preempt_disable-ed region")
 int preempt_lock_missing_2(struct __sk_buff *ctx)
 {
 	bpf_preempt_disable();
@@ -23,7 +23,7 @@ int preempt_lock_missing_2(struct __sk_buff *ctx)
 }
 
 SEC("?tc")
-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_preempt_disable-ed region")
+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_preempt_disable-ed region")
 int preempt_lock_missing_3(struct __sk_buff *ctx)
 {
 	bpf_preempt_disable();
@@ -33,7 +33,7 @@ int preempt_lock_missing_3(struct __sk_buff *ctx)
 }
 
 SEC("?tc")
-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_preempt_disable-ed region")
+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_preempt_disable-ed region")
 int preempt_lock_missing_3_minus_2(struct __sk_buff *ctx)
 {
 	bpf_preempt_disable();
@@ -55,15 +55,15 @@ static __noinline void preempt_enable(void)
 }
 
 SEC("?tc")
-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_preempt_disable-ed region")
+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_preempt_disable-ed region")
 int preempt_lock_missing_1_subprog(struct __sk_buff *ctx)
 {
 	preempt_disable();
 	return 0;
 }
 
 SEC("?tc")
-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_preempt_disable-ed region")
+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_preempt_disable-ed region")
 int preempt_lock_missing_2_subprog(struct __sk_buff *ctx)
 {
 	preempt_disable();
@@ -72,7 +72,7 @@ int preempt_lock_missing_2_subprog(struct __sk_buff *ctx)
 }
 
 SEC("?tc")
-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_preempt_disable-ed region")
+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_preempt_disable-ed region")
 int preempt_lock_missing_2_minus_1_subprog(struct __sk_buff *ctx)
 {
 	preempt_disable();
diff --git a/tools/testing/selftests/bpf/progs/verifier_spin_lock.c b/tools/testing/selftests/bpf/progs/verifier_spin_lock.c
@@ -187,7 +187,7 @@ l0_%=:	r6 = r0;					\
 
 SEC("cgroup/skb")
 __description("spin_lock: test6 missing unlock")
-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_spin_lock-ed region")
+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_spin_lock-ed region")
 __failure_unpriv __msg_unpriv("")
 __naked void spin_lock_test6_missing_unlock(void)
 {

Original file line number	Diff line number	Diff line change
`@@ -131,7 +131,7 @@ int reject_subprog_with_lock(void *ctx)`
`131`	`131`	`}`
`132`	`132`
`133`	`133`	`SEC("?tc")`
`134`		`-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_rcu_read_lock-ed region")`
	`134`	`+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_rcu_read_lock-ed region")`
`135`	`135`	`int reject_with_rcu_read_lock(void *ctx)`
`136`	`136`	`{`
`137`	`137`	`bpf_rcu_read_lock();`
`@@ -147,7 +147,7 @@ __noinline static int throwing_subprog(struct __sk_buff *ctx)`
`147`	`147`	`}`
`148`	`148`
`149`	`149`	`SEC("?tc")`
`150`		`-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_rcu_read_lock-ed region")`
	`150`	`+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_rcu_read_lock-ed region")`
`151`	`151`	`int reject_subprog_with_rcu_read_lock(void *ctx)`
`152`	`152`	`{`
`153`	`153`	`bpf_rcu_read_lock();`
Original file line number	Diff line number	Diff line change
`@@ -6,15 +6,15 @@`
`6`	`6`	`#include "bpf_experimental.h"`
`7`	`7`
`8`	`8`	`SEC("?tc")`
`9`		`-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_preempt_disable-ed region")`
	`9`	`+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_preempt_disable-ed region")`
`10`	`10`	`int preempt_lock_missing_1(struct __sk_buff *ctx)`
`11`	`11`	`{`
`12`	`12`	`bpf_preempt_disable();`
`13`	`13`	`return 0;`
`14`	`14`	`}`
`15`	`15`
`16`	`16`	`SEC("?tc")`
`17`		`-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_preempt_disable-ed region")`
	`17`	`+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_preempt_disable-ed region")`
`18`	`18`	`int preempt_lock_missing_2(struct __sk_buff *ctx)`
`19`	`19`	`{`
`20`	`20`	`bpf_preempt_disable();`
`@@ -23,7 +23,7 @@ int preempt_lock_missing_2(struct __sk_buff *ctx)`
`23`	`23`	`}`
`24`	`24`
`25`	`25`	`SEC("?tc")`
`26`		`-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_preempt_disable-ed region")`
	`26`	`+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_preempt_disable-ed region")`
`27`	`27`	`int preempt_lock_missing_3(struct __sk_buff *ctx)`
`28`	`28`	`{`
`29`	`29`	`bpf_preempt_disable();`
`@@ -33,7 +33,7 @@ int preempt_lock_missing_3(struct __sk_buff *ctx)`
`33`	`33`	`}`
`34`	`34`
`35`	`35`	`SEC("?tc")`
`36`		`-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_preempt_disable-ed region")`
	`36`	`+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_preempt_disable-ed region")`
`37`	`37`	`int preempt_lock_missing_3_minus_2(struct __sk_buff *ctx)`
`38`	`38`	`{`
`39`	`39`	`bpf_preempt_disable();`
`@@ -55,15 +55,15 @@ static __noinline void preempt_enable(void)`
`55`	`55`	`}`
`56`	`56`
`57`	`57`	`SEC("?tc")`
`58`		`-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_preempt_disable-ed region")`
	`58`	`+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_preempt_disable-ed region")`
`59`	`59`	`int preempt_lock_missing_1_subprog(struct __sk_buff *ctx)`
`60`	`60`	`{`
`61`	`61`	`preempt_disable();`
`62`	`62`	`return 0;`
`63`	`63`	`}`
`64`	`64`
`65`	`65`	`SEC("?tc")`
`66`		`-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_preempt_disable-ed region")`
	`66`	`+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_preempt_disable-ed region")`
`67`	`67`	`int preempt_lock_missing_2_subprog(struct __sk_buff *ctx)`
`68`	`68`	`{`
`69`	`69`	`preempt_disable();`
`@@ -72,7 +72,7 @@ int preempt_lock_missing_2_subprog(struct __sk_buff *ctx)`
`72`	`72`	`}`
`73`	`73`
`74`	`74`	`SEC("?tc")`
`75`		`-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_preempt_disable-ed region")`
	`75`	`+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_preempt_disable-ed region")`
`76`	`76`	`int preempt_lock_missing_2_minus_1_subprog(struct __sk_buff *ctx)`
`77`	`77`	`{`
`78`	`78`	`preempt_disable();`
Original file line number	Diff line number	Diff line change
`@@ -187,7 +187,7 @@ l0_%=: r6 = r0; \`
`187`	`187`
`188`	`188`	`SEC("cgroup/skb")`
`189`	`189`	`__description("spin_lock: test6 missing unlock")`
`190`		`-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_spin_lock-ed region")`
	`190`	`+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_spin_lock-ed region")`
`191`	`191`	`__failure_unpriv __msg_unpriv("")`
`192`	`192`	`__naked void spin_lock_test6_missing_unlock(void)`
`193`	`193`	`{`