| Message ID | 20220617042038.4003704-1-windhl@126.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | powerpc: powernv: Fix refcount leak bug in opal-powercap | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/github-powerpc_sparse | success | Successfully ran 4 jobs. |
| snowpatch_ozlabs/github-powerpc_ppctests | success | Successfully ran 10 jobs. |
| snowpatch_ozlabs/github-powerpc_selftests | success | Successfully ran 10 jobs. |
| snowpatch_ozlabs/github-powerpc_clang | success | Successfully ran 7 jobs. |
| snowpatch_ozlabs/github-powerpc_kernel_qemu | success | Successfully ran 23 jobs. |
Le 17/06/2022 à 06:20, Liang He a écrit : > In opal_powercap_init(), of_find_compatible_node() will return > a node pointer with refcount incremented. We should use of_node_put() > in fail path or when it is not used anymore. > > Besides, for_each_child_of_node() will automatically *inc* and *dec* > refcount during iteration. However, we should add the of_node_put() > if there is a break. Hi, I'm not sure that your patch is right here. Because of this *inc* and *dec* things, do we still need to of_node_put(powercap) once we have entered for_each_child_of_node? I think that this reference will be released on the first iteration of the loop. Maybe of_node_put(powercap) should be duplicated everywhere it is relevant and removed from the error handling path? Or an additional reference should be taken before the loop? Or adding a new label with "powercap = NULL" and branching there when needed? CJ > > Signed-off-by: Liang He <windhl@126.com> > --- > arch/powerpc/platforms/powernv/opal-powercap.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/platforms/powernv/opal-powercap.c b/arch/powerpc/platforms/powernv/opal-powercap.c > index 64506b46e77b..b102477d3f95 100644 > --- a/arch/powerpc/platforms/powernv/opal-powercap.c > +++ b/arch/powerpc/platforms/powernv/opal-powercap.c > @@ -153,7 +153,7 @@ void __init opal_powercap_init(void) > pcaps = kcalloc(of_get_child_count(powercap), sizeof(*pcaps), > GFP_KERNEL); > if (!pcaps) > - return; > + goto out_powercap; > > powercap_kobj = kobject_create_and_add("powercap", opal_kobj); > if (!powercap_kobj) { > @@ -236,6 +236,9 @@ void __init opal_powercap_init(void) > kfree(pcaps[i].pg.name); > } > kobject_put(powercap_kobj); > + of_node_put(node); > out_pcaps: > kfree(pcaps); > +out_powercap: > + of_node_put(powercap); > }
At 2022-06-17 13:01:27, "Christophe JAILLET" <christophe.jaillet@wanadoo.fr> wrote: >Le 17/06/2022 à 06:20, Liang He a écrit : >> In opal_powercap_init(), of_find_compatible_node() will return >> a node pointer with refcount incremented. We should use of_node_put() >> in fail path or when it is not used anymore. >> >> Besides, for_each_child_of_node() will automatically *inc* and *dec* >> refcount during iteration. However, we should add the of_node_put() >> if there is a break. > >Hi, > >I'm not sure that your patch is right here. Because of this *inc* and >*dec* things, do we still need to of_node_put(powercap) once we have >entered for_each_child_of_node? > >I think that this reference will be released on the first iteration of >the loop. > Hi, CJ, Thanks for your reply and I want have a discuss. Based on my review on the src of 'of_get_next_child', there is only *inc* for next and *dec* for pre as follow. (|node| == powercap) ======__of_get_next_child( |node|, prev)====== ... next = prev? prev->sibling:|node|->child; of_node_get(next); of_node_put(prev); ... ========================= However, there is no any code to release the |node| (i.e., *powercap*). Am I right? If I am wrong, please correct me, thanks. > >Maybe of_node_put(powercap) should be duplicated everywhere it is >relevant and removed from the error handling path? >Or an additional reference should be taken before the loop? >Or adding a new label with "powercap = NULL" and branching there when >needed? > >CJ If my understanding is right, I think current patch is right. Otherwise, I will make a new patch to handle that, Thanks. Liang > >> >> Signed-off-by: Liang He <windhl@126.com> >> --- >> arch/powerpc/platforms/powernv/opal-powercap.c | 5 ++++- >> 1 file changed, 4 insertions(+), 1 deletion(-) >> >> diff --git a/arch/powerpc/platforms/powernv/opal-powercap.c b/arch/powerpc/platforms/powernv/opal-powercap.c >> index 64506b46e77b..b102477d3f95 100644 >> --- a/arch/powerpc/platforms/powernv/opal-powercap.c >> +++ b/arch/powerpc/platforms/powernv/opal-powercap.c >> @@ -153,7 +153,7 @@ void __init opal_powercap_init(void) >> pcaps = kcalloc(of_get_child_count(powercap), sizeof(*pcaps), >> GFP_KERNEL); >> if (!pcaps) >> - return; >> + goto out_powercap; >> >> powercap_kobj = kobject_create_and_add("powercap", opal_kobj); >> if (!powercap_kobj) { >> @@ -236,6 +236,9 @@ void __init opal_powercap_init(void) >> kfree(pcaps[i].pg.name); >> } >> kobject_put(powercap_kobj); >> + of_node_put(node); >> out_pcaps: >> kfree(pcaps); >> +out_powercap: >> + of_node_put(powercap); >> }
At 2022-06-17 13:01:27, "Christophe JAILLET" <christophe.jaillet@wanadoo.fr> wrote: >Le 17/06/2022 à 06:20, Liang He a écrit : >> In opal_powercap_init(), of_find_compatible_node() will return >> a node pointer with refcount incremented. We should use of_node_put() >> in fail path or when it is not used anymore. >> >> Besides, for_each_child_of_node() will automatically *inc* and *dec* >> refcount during iteration. However, we should add the of_node_put() >> if there is a break. > >Hi, > >I'm not sure that your patch is right here. Because of this *inc* and >*dec* things, do we still need to of_node_put(powercap) once we have >entered for_each_child_of_node? > >I think that this reference will be released on the first iteration of >the loop. > > >Maybe of_node_put(powercap) should be duplicated everywhere it is >relevant and removed from the error handling path? >Or an additional reference should be taken before the loop? >Or adding a new label with "powercap = NULL" and branching there when >needed? > >CJ > >> >> Signed-off-by: Liang He <windhl@126.com> >> --- >> arch/powerpc/platforms/powernv/opal-powercap.c | 5 ++++- >> 1 file changed, 4 insertions(+), 1 deletion(-) >> >> diff --git a/arch/powerpc/platforms/powernv/opal-powercap.c b/arch/powerpc/platforms/powernv/opal-powercap.c >> index 64506b46e77b..b102477d3f95 100644 >> --- a/arch/powerpc/platforms/powernv/opal-powercap.c >> +++ b/arch/powerpc/platforms/powernv/opal-powercap.c >> @@ -153,7 +153,7 @@ void __init opal_powercap_init(void) >> pcaps = kcalloc(of_get_child_count(powercap), sizeof(*pcaps), >> GFP_KERNEL); >> if (!pcaps) >> - return; >> + goto out_powercap; >> >> powercap_kobj = kobject_create_and_add("powercap", opal_kobj); >> if (!powercap_kobj) { >> @@ -236,6 +236,9 @@ void __init opal_powercap_init(void) >> kfree(pcaps[i].pg.name); >> } >> kobject_put(powercap_kobj); >> + of_node_put(node); >> out_pcaps: >> kfree(pcaps); >> +out_powercap: >> + of_node_put(powercap); >> } Hi, CJ. I think my patch is correct based on the old commit: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.19-rc2&id=09700c504d8e63faffd2a2235074e8c5d130cb8f Bugs and fix solutions in this 09700c504d8e63-commit are very similar with mine. Besides, I also find similar new bugs in other two files in the same directory 'powernv', so I have merged all three files' patches into one commit. '[PATCH v2] powerpc: powernv: Fix refcount leak bug'. Thanks. Liang
Le 17/06/2022 à 07:42, Liang He a écrit : > > > > At 2022-06-17 13:01:27, "Christophe JAILLET" <christophe.jaillet@wanadoo.fr> wrote: >> Le 17/06/2022 à 06:20, Liang He a écrit : >>> In opal_powercap_init(), of_find_compatible_node() will return >>> a node pointer with refcount incremented. We should use of_node_put() >>> in fail path or when it is not used anymore. >>> >>> Besides, for_each_child_of_node() will automatically *inc* and *dec* >>> refcount during iteration. However, we should add the of_node_put() >>> if there is a break. >> >> Hi, >> >> I'm not sure that your patch is right here. Because of this *inc* and >> *dec* things, do we still need to of_node_put(powercap) once we have >> entered for_each_child_of_node? >> >> I think that this reference will be released on the first iteration of >> the loop. >> > > Hi, CJ, > > Thanks for your reply and I want have a discuss. > > Based on my review on the src of 'of_get_next_child', there is only > *inc* for next and *dec* for pre as follow. > > (|node| == powercap) > ======__of_get_next_child( |node|, prev)====== > ... > next = prev? prev->sibling:|node|->child; > of_node_get(next); > of_node_put(prev); > ... > ========================= > > However, there is no any code to release the |node| (i.e., *powercap*). > > Am I right? If I am wrong, please correct me, thanks. You are right. I mis-read __of_get_next_child((). CJ > >> >> Maybe of_node_put(powercap) should be duplicated everywhere it is >> relevant and removed from the error handling path? >> Or an additional reference should be taken before the loop? >> Or adding a new label with "powercap = NULL" and branching there when >> needed? >> >> CJ > > If my understanding is right, I think current patch is right. > > Otherwise, I will make a new patch to handle that, Thanks. > > Liang > >> >>> >>> Signed-off-by: Liang He <windhl@126.com> >>> --- >>> arch/powerpc/platforms/powernv/opal-powercap.c | 5 ++++- >>> 1 file changed, 4 insertions(+), 1 deletion(-) >>> >>> diff --git a/arch/powerpc/platforms/powernv/opal-powercap.c b/arch/powerpc/platforms/powernv/opal-powercap.c >>> index 64506b46e77b..b102477d3f95 100644 >>> --- a/arch/powerpc/platforms/powernv/opal-powercap.c >>> +++ b/arch/powerpc/platforms/powernv/opal-powercap.c >>> @@ -153,7 +153,7 @@ void __init opal_powercap_init(void) >>> pcaps = kcalloc(of_get_child_count(powercap), sizeof(*pcaps), >>> GFP_KERNEL); >>> if (!pcaps) >>> - return; >>> + goto out_powercap; >>> >>> powercap_kobj = kobject_create_and_add("powercap", opal_kobj); >>> if (!powercap_kobj) { >>> @@ -236,6 +236,9 @@ void __init opal_powercap_init(void) >>> kfree(pcaps[i].pg.name); >>> } >>> kobject_put(powercap_kobj); >>> + of_node_put(node); >>> out_pcaps: >>> kfree(pcaps); >>> +out_powercap: >>> + of_node_put(powercap); >>> }
diff --git a/arch/powerpc/platforms/powernv/opal-powercap.c b/arch/powerpc/platforms/powernv/opal-powercap.c index 64506b46e77b..b102477d3f95 100644 --- a/arch/powerpc/platforms/powernv/opal-powercap.c +++ b/arch/powerpc/platforms/powernv/opal-powercap.c @@ -153,7 +153,7 @@ void __init opal_powercap_init(void) pcaps = kcalloc(of_get_child_count(powercap), sizeof(*pcaps), GFP_KERNEL); if (!pcaps) - return; + goto out_powercap; powercap_kobj = kobject_create_and_add("powercap", opal_kobj); if (!powercap_kobj) { @@ -236,6 +236,9 @@ void __init opal_powercap_init(void) kfree(pcaps[i].pg.name); } kobject_put(powercap_kobj); + of_node_put(node); out_pcaps: kfree(pcaps); +out_powercap: + of_node_put(powercap); }
In opal_powercap_init(), of_find_compatible_node() will return a node pointer with refcount incremented. We should use of_node_put() in fail path or when it is not used anymore. Besides, for_each_child_of_node() will automatically *inc* and *dec* refcount during iteration. However, we should add the of_node_put() if there is a break. Signed-off-by: Liang He <windhl@126.com> --- arch/powerpc/platforms/powernv/opal-powercap.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)