* [PATCH] efivarfs: revert "fix memory leak in efivarfs_create()"
@ 2020-11-25 7:53 Ard Biesheuvel
2020-11-25 8:05 ` Oleksandr Natalenko
2020-11-25 10:27 ` Oleksandr Natalenko
0 siblings, 2 replies; 9+ messages in thread
From: Ard Biesheuvel @ 2020-11-25 7:53 UTC (permalink / raw)
To: linux-efi
Cc: oleksandr, jk, mjg59, David.Laight, Ard Biesheuvel,
Vamshi K Sthambamkadi
The memory leak addressed by commit fe5186cf12e3 is a false positive:
all allocations are recorded in a linked list, and freed when the
filesystem is unmounted. This leads to double frees, and as reported
by David, leads to crashes if SLUB is configured to self destruct when
double frees occur.
So drop the redundant kfree() again, and instead, mark the offending
pointer variable so the allocation is ignored by kmemleak.
Cc: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com>
Fixes: fe5186cf12e3 ("efivarfs: fix memory leak in efivarfs_create()")
Reported-by: David Laight <David.Laight@aculab.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
fs/efivarfs/inode.c | 1 +
fs/efivarfs/super.c | 1 -
2 files changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/efivarfs/inode.c b/fs/efivarfs/inode.c
index 96c0c86f3fff..38324427a2b3 100644
--- a/fs/efivarfs/inode.c
+++ b/fs/efivarfs/inode.c
@@ -103,6 +103,7 @@ static int efivarfs_create(struct inode *dir, struct dentry *dentry,
var->var.VariableName[i] = '\0';
inode->i_private = var;
+ kmemleak_ignore(var);
err = efivar_entry_add(var, &efivarfs_list);
if (err)
diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c
index f943fd0b0699..15880a68faad 100644
--- a/fs/efivarfs/super.c
+++ b/fs/efivarfs/super.c
@@ -21,7 +21,6 @@ LIST_HEAD(efivarfs_list);
static void efivarfs_evict_inode(struct inode *inode)
{
clear_inode(inode);
- kfree(inode->i_private);
}
static const struct super_operations efivarfs_ops = {
--
2.17.1
^ permalink raw reply related [flat|nested] 9+ messages in thread* Re: [PATCH] efivarfs: revert "fix memory leak in efivarfs_create()"
2020-11-25 7:53 [PATCH] efivarfs: revert "fix memory leak in efivarfs_create()" Ard Biesheuvel
@ 2020-11-25 8:05 ` Oleksandr Natalenko
2020-11-25 8:05 ` Ard Biesheuvel
2020-11-25 10:27 ` Oleksandr Natalenko
1 sibling, 1 reply; 9+ messages in thread
From: Oleksandr Natalenko @ 2020-11-25 8:05 UTC (permalink / raw)
To: Ard Biesheuvel
Cc: linux-efi, jk, mjg59, David.Laight, Vamshi K Sthambamkadi,
stable, Greg Kroah-Hartman
Hello.
On 25.11.2020 08:53, Ard Biesheuvel wrote:
> The memory leak addressed by commit fe5186cf12e3 is a false positive:
> all allocations are recorded in a linked list, and freed when the
> filesystem is unmounted. This leads to double frees, and as reported
> by David, leads to crashes if SLUB is configured to self destruct when
> double frees occur.
>
> So drop the redundant kfree() again, and instead, mark the offending
> pointer variable so the allocation is ignored by kmemleak.
>
> Cc: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com>
Should also have:
Cc: <stable@vger.kernel.org> # v5.9
> Fixes: fe5186cf12e3 ("efivarfs: fix memory leak in efivarfs_create()")
> Reported-by: David Laight <David.Laight@aculab.com>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> ---
> fs/efivarfs/inode.c | 1 +
> fs/efivarfs/super.c | 1 -
> 2 files changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/efivarfs/inode.c b/fs/efivarfs/inode.c
> index 96c0c86f3fff..38324427a2b3 100644
> --- a/fs/efivarfs/inode.c
> +++ b/fs/efivarfs/inode.c
> @@ -103,6 +103,7 @@ static int efivarfs_create(struct inode *dir,
> struct dentry *dentry,
> var->var.VariableName[i] = '\0';
>
> inode->i_private = var;
> + kmemleak_ignore(var);
>
> err = efivar_entry_add(var, &efivarfs_list);
> if (err)
> diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c
> index f943fd0b0699..15880a68faad 100644
> --- a/fs/efivarfs/super.c
> +++ b/fs/efivarfs/super.c
> @@ -21,7 +21,6 @@ LIST_HEAD(efivarfs_list);
> static void efivarfs_evict_inode(struct inode *inode)
> {
> clear_inode(inode);
> - kfree(inode->i_private);
> }
>
> static const struct super_operations efivarfs_ops = {
--
Oleksandr Natalenko (post-factum)
^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [PATCH] efivarfs: revert "fix memory leak in efivarfs_create()"
2020-11-25 8:05 ` Oleksandr Natalenko
@ 2020-11-25 8:05 ` Ard Biesheuvel
2020-11-25 8:25 ` Greg Kroah-Hartman
0 siblings, 1 reply; 9+ messages in thread
From: Ard Biesheuvel @ 2020-11-25 8:05 UTC (permalink / raw)
To: Oleksandr Natalenko
Cc: linux-efi, Jeremy Kerr, Matthew Garrett, David Laight,
Vamshi K Sthambamkadi, # 3.4.x, Greg Kroah-Hartman
On Wed, 25 Nov 2020 at 09:05, Oleksandr Natalenko
<oleksandr@natalenko.name> wrote:
>
> Hello.
>
> On 25.11.2020 08:53, Ard Biesheuvel wrote:
> > The memory leak addressed by commit fe5186cf12e3 is a false positive:
> > all allocations are recorded in a linked list, and freed when the
> > filesystem is unmounted. This leads to double frees, and as reported
> > by David, leads to crashes if SLUB is configured to self destruct when
> > double frees occur.
> >
> > So drop the redundant kfree() again, and instead, mark the offending
> > pointer variable so the allocation is ignored by kmemleak.
> >
> > Cc: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com>
>
> Should also have:
>
> Cc: <stable@vger.kernel.org> # v5.9
>
No it should not. The fixes tag should be sufficient.
> > Fixes: fe5186cf12e3 ("efivarfs: fix memory leak in efivarfs_create()")
> > Reported-by: David Laight <David.Laight@aculab.com>
> > Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> > ---
> > fs/efivarfs/inode.c | 1 +
> > fs/efivarfs/super.c | 1 -
> > 2 files changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/efivarfs/inode.c b/fs/efivarfs/inode.c
> > index 96c0c86f3fff..38324427a2b3 100644
> > --- a/fs/efivarfs/inode.c
> > +++ b/fs/efivarfs/inode.c
> > @@ -103,6 +103,7 @@ static int efivarfs_create(struct inode *dir,
> > struct dentry *dentry,
> > var->var.VariableName[i] = '\0';
> >
> > inode->i_private = var;
> > + kmemleak_ignore(var);
> >
> > err = efivar_entry_add(var, &efivarfs_list);
> > if (err)
> > diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c
> > index f943fd0b0699..15880a68faad 100644
> > --- a/fs/efivarfs/super.c
> > +++ b/fs/efivarfs/super.c
> > @@ -21,7 +21,6 @@ LIST_HEAD(efivarfs_list);
> > static void efivarfs_evict_inode(struct inode *inode)
> > {
> > clear_inode(inode);
> > - kfree(inode->i_private);
> > }
> >
> > static const struct super_operations efivarfs_ops = {
>
> --
> Oleksandr Natalenko (post-factum)
^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [PATCH] efivarfs: revert "fix memory leak in efivarfs_create()"
2020-11-25 8:05 ` Ard Biesheuvel
@ 2020-11-25 8:25 ` Greg Kroah-Hartman
0 siblings, 0 replies; 9+ messages in thread
From: Greg Kroah-Hartman @ 2020-11-25 8:25 UTC (permalink / raw)
To: Ard Biesheuvel
Cc: Oleksandr Natalenko, linux-efi, Jeremy Kerr, Matthew Garrett,
David Laight, Vamshi K Sthambamkadi, # 3.4.x
On Wed, Nov 25, 2020 at 09:05:42AM +0100, Ard Biesheuvel wrote:
> On Wed, 25 Nov 2020 at 09:05, Oleksandr Natalenko
> <oleksandr@natalenko.name> wrote:
> >
> > Hello.
> >
> > On 25.11.2020 08:53, Ard Biesheuvel wrote:
> > > The memory leak addressed by commit fe5186cf12e3 is a false positive:
> > > all allocations are recorded in a linked list, and freed when the
> > > filesystem is unmounted. This leads to double frees, and as reported
> > > by David, leads to crashes if SLUB is configured to self destruct when
> > > double frees occur.
> > >
> > > So drop the redundant kfree() again, and instead, mark the offending
> > > pointer variable so the allocation is ignored by kmemleak.
> > >
> > > Cc: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com>
> >
> > Should also have:
> >
> > Cc: <stable@vger.kernel.org> # v5.9
> >
>
> No it should not. The fixes tag should be sufficient.
No, "Fixes:" does not ever mean "I want this patch to go to a stable
tree". It might happen, it might not, if you REALLY know this should go
to a stable tree, please follow the directions for what we have been
doing for 15+ years now, as documented in:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
Hint, use "cc: stable@vger.kernel.org" if you know you want it applied,
otherwise it's just a best-guess-effort on our part.
thanks,
greg k-h
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] efivarfs: revert "fix memory leak in efivarfs_create()"
2020-11-25 7:53 [PATCH] efivarfs: revert "fix memory leak in efivarfs_create()" Ard Biesheuvel
2020-11-25 8:05 ` Oleksandr Natalenko
@ 2020-11-25 10:27 ` Oleksandr Natalenko
2020-11-25 10:28 ` Ard Biesheuvel
1 sibling, 1 reply; 9+ messages in thread
From: Oleksandr Natalenko @ 2020-11-25 10:27 UTC (permalink / raw)
To: Ard Biesheuvel; +Cc: linux-efi, jk, mjg59, David.Laight, Vamshi K Sthambamkadi
On 25.11.2020 08:53, Ard Biesheuvel wrote:
> The memory leak addressed by commit fe5186cf12e3 is a false positive:
> all allocations are recorded in a linked list, and freed when the
> filesystem is unmounted. This leads to double frees, and as reported
> by David, leads to crashes if SLUB is configured to self destruct when
> double frees occur.
>
> So drop the redundant kfree() again, and instead, mark the offending
> pointer variable so the allocation is ignored by kmemleak.
>
> Cc: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com>
> Fixes: fe5186cf12e3 ("efivarfs: fix memory leak in efivarfs_create()")
> Reported-by: David Laight <David.Laight@aculab.com>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> ---
> fs/efivarfs/inode.c | 1 +
> fs/efivarfs/super.c | 1 -
> 2 files changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/efivarfs/inode.c b/fs/efivarfs/inode.c
> index 96c0c86f3fff..38324427a2b3 100644
> --- a/fs/efivarfs/inode.c
> +++ b/fs/efivarfs/inode.c
> @@ -103,6 +103,7 @@ static int efivarfs_create(struct inode *dir,
> struct dentry *dentry,
> var->var.VariableName[i] = '\0';
>
> inode->i_private = var;
> + kmemleak_ignore(var);
Do we need to do this as well:
#include <linux/kmemleak.h>
?
Because otherwise for 5.9 I get:
[ 148s] fs/efivarfs/inode.c: In function 'efivarfs_create':
[ 148s] fs/efivarfs/inode.c:106:2: error: implicit declaration of
function 'kmemleak_ignore' [-Werror=implicit-function-declaration]
[ 148s] 106 | kmemleak_ignore(var);
[ 148s] | ^~~~~~~~~~~~~~~
>
> err = efivar_entry_add(var, &efivarfs_list);
> if (err)
> diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c
> index f943fd0b0699..15880a68faad 100644
> --- a/fs/efivarfs/super.c
> +++ b/fs/efivarfs/super.c
> @@ -21,7 +21,6 @@ LIST_HEAD(efivarfs_list);
> static void efivarfs_evict_inode(struct inode *inode)
> {
> clear_inode(inode);
> - kfree(inode->i_private);
> }
>
> static const struct super_operations efivarfs_ops = {
--
Oleksandr Natalenko (post-factum)
^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [PATCH] efivarfs: revert "fix memory leak in efivarfs_create()"
2020-11-25 10:27 ` Oleksandr Natalenko
@ 2020-11-25 10:28 ` Ard Biesheuvel
2020-11-27 16:50 ` Jonathon Fernyhough
0 siblings, 1 reply; 9+ messages in thread
From: Ard Biesheuvel @ 2020-11-25 10:28 UTC (permalink / raw)
To: Oleksandr Natalenko
Cc: linux-efi, Jeremy Kerr, Matthew Garrett, David Laight,
Vamshi K Sthambamkadi
On Wed, 25 Nov 2020 at 11:27, Oleksandr Natalenko
<oleksandr@natalenko.name> wrote:
>
> On 25.11.2020 08:53, Ard Biesheuvel wrote:
> > The memory leak addressed by commit fe5186cf12e3 is a false positive:
> > all allocations are recorded in a linked list, and freed when the
> > filesystem is unmounted. This leads to double frees, and as reported
> > by David, leads to crashes if SLUB is configured to self destruct when
> > double frees occur.
> >
> > So drop the redundant kfree() again, and instead, mark the offending
> > pointer variable so the allocation is ignored by kmemleak.
> >
> > Cc: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com>
> > Fixes: fe5186cf12e3 ("efivarfs: fix memory leak in efivarfs_create()")
> > Reported-by: David Laight <David.Laight@aculab.com>
> > Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> > ---
> > fs/efivarfs/inode.c | 1 +
> > fs/efivarfs/super.c | 1 -
> > 2 files changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/efivarfs/inode.c b/fs/efivarfs/inode.c
> > index 96c0c86f3fff..38324427a2b3 100644
> > --- a/fs/efivarfs/inode.c
> > +++ b/fs/efivarfs/inode.c
> > @@ -103,6 +103,7 @@ static int efivarfs_create(struct inode *dir,
> > struct dentry *dentry,
> > var->var.VariableName[i] = '\0';
> >
> > inode->i_private = var;
> > + kmemleak_ignore(var);
>
> Do we need to do this as well:
>
> #include <linux/kmemleak.h>
>
> ?
>
> Because otherwise for 5.9 I get:
>
> [ 148s] fs/efivarfs/inode.c: In function 'efivarfs_create':
> [ 148s] fs/efivarfs/inode.c:106:2: error: implicit declaration of
> function 'kmemleak_ignore' [-Werror=implicit-function-declaration]
> [ 148s] 106 | kmemleak_ignore(var);
> [ 148s] | ^~~~~~~~~~~~~~~
>
Ah yes, thanks for the report. I will add the include to the patch.
> >
> > err = efivar_entry_add(var, &efivarfs_list);
> > if (err)
> > diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c
> > index f943fd0b0699..15880a68faad 100644
> > --- a/fs/efivarfs/super.c
> > +++ b/fs/efivarfs/super.c
> > @@ -21,7 +21,6 @@ LIST_HEAD(efivarfs_list);
> > static void efivarfs_evict_inode(struct inode *inode)
> > {
> > clear_inode(inode);
> > - kfree(inode->i_private);
> > }
> >
> > static const struct super_operations efivarfs_ops = {
>
> --
> Oleksandr Natalenko (post-factum)
^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [PATCH] efivarfs: revert "fix memory leak in efivarfs_create()"
2020-11-25 10:28 ` Ard Biesheuvel
@ 2020-11-27 16:50 ` Jonathon Fernyhough
2020-11-27 16:58 ` Ard Biesheuvel
2020-11-27 16:59 ` Oleksandr Natalenko
0 siblings, 2 replies; 9+ messages in thread
From: Jonathon Fernyhough @ 2020-11-27 16:50 UTC (permalink / raw)
To: Ard Biesheuvel, Oleksandr Natalenko
Cc: linux-efi, Jeremy Kerr, Matthew Garrett, David Laight,
Vamshi K Sthambamkadi
[-- Attachment #1.1: Type: text/plain, Size: 861 bytes --]
On 25/11/2020 10:28, Ard Biesheuvel wrote:
> On Wed, 25 Nov 2020 at 11:27, Oleksandr Natalenko
> <oleksandr@natalenko.name> wrote:
>>
>> On 25.11.2020 08:53, Ard Biesheuvel wrote:
--snip--
>>
>> Do we need to do this as well:
>>
>> #include <linux/kmemleak.h>
>>
>> ?
>>
>> Because otherwise for 5.9 I get:
>>
>> [ 148s] fs/efivarfs/inode.c: In function 'efivarfs_create':
>> [ 148s] fs/efivarfs/inode.c:106:2: error: implicit declaration of
>> function 'kmemleak_ignore' [-Werror=implicit-function-declaration]
>> [ 148s] 106 | kmemleak_ignore(var);
>> [ 148s] | ^~~~~~~~~~~~~~~
>>
>
> Ah yes, thanks for the report. I will add the include to the patch.
>
>
Is this necessary if CONFIG_DEBUG_KMEMLEAK is not enabled in the kernel
config? e.g. should there be an #ifdef CONFIG_DEBUG_KMEMLEAK somewhere
in there?
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^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] efivarfs: revert "fix memory leak in efivarfs_create()"
2020-11-27 16:50 ` Jonathon Fernyhough
@ 2020-11-27 16:58 ` Ard Biesheuvel
2020-11-27 16:59 ` Oleksandr Natalenko
1 sibling, 0 replies; 9+ messages in thread
From: Ard Biesheuvel @ 2020-11-27 16:58 UTC (permalink / raw)
To: Jonathon Fernyhough
Cc: Oleksandr Natalenko, linux-efi, Jeremy Kerr, Matthew Garrett,
David Laight, Vamshi K Sthambamkadi
On Fri, 27 Nov 2020 at 17:56, Jonathon Fernyhough <jonathon@m2x.dev> wrote:
>
> On 25/11/2020 10:28, Ard Biesheuvel wrote:
> > On Wed, 25 Nov 2020 at 11:27, Oleksandr Natalenko
> > <oleksandr@natalenko.name> wrote:
> >>
> >> On 25.11.2020 08:53, Ard Biesheuvel wrote:
> --snip--
> >>
> >> Do we need to do this as well:
> >>
> >> #include <linux/kmemleak.h>
> >>
> >> ?
> >>
> >> Because otherwise for 5.9 I get:
> >>
> >> [ 148s] fs/efivarfs/inode.c: In function 'efivarfs_create':
> >> [ 148s] fs/efivarfs/inode.c:106:2: error: implicit declaration of
> >> function 'kmemleak_ignore' [-Werror=implicit-function-declaration]
> >> [ 148s] 106 | kmemleak_ignore(var);
> >> [ 148s] | ^~~~~~~~~~~~~~~
> >>
> >
> > Ah yes, thanks for the report. I will add the include to the patch.
> >
> >
>
> Is this necessary if CONFIG_DEBUG_KMEMLEAK is not enabled in the kernel
> config? e.g. should there be an #ifdef CONFIG_DEBUG_KMEMLEAK somewhere
> in there?
>
We typically define these helpers unconditionally, and sort out the
differences in the header file. In this case, we have
static inline void kmemleak_ignore(const void *ptr)
{
}
in include/linux/kmemleak.h if CONFIG_DEBUG_KMEMLEAK is not set.
This makes the calling code much cleaner.
^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [PATCH] efivarfs: revert "fix memory leak in efivarfs_create()"
2020-11-27 16:50 ` Jonathon Fernyhough
2020-11-27 16:58 ` Ard Biesheuvel
@ 2020-11-27 16:59 ` Oleksandr Natalenko
1 sibling, 0 replies; 9+ messages in thread
From: Oleksandr Natalenko @ 2020-11-27 16:59 UTC (permalink / raw)
To: Jonathon Fernyhough
Cc: Ard Biesheuvel, linux-efi, Jeremy Kerr, Matthew Garrett,
David Laight, Vamshi K Sthambamkadi
Hi.
On Fri, Nov 27, 2020 at 04:50:34PM +0000, Jonathon Fernyhough wrote:
> On 25/11/2020 10:28, Ard Biesheuvel wrote:
> > On Wed, 25 Nov 2020 at 11:27, Oleksandr Natalenko
> > <oleksandr@natalenko.name> wrote:
> >>
> >> On 25.11.2020 08:53, Ard Biesheuvel wrote:
> --snip--
> >>
> >> Do we need to do this as well:
> >>
> >> #include <linux/kmemleak.h>
> >>
> >> ?
> >>
> >> Because otherwise for 5.9 I get:
> >>
> >> [ 148s] fs/efivarfs/inode.c: In function 'efivarfs_create':
> >> [ 148s] fs/efivarfs/inode.c:106:2: error: implicit declaration of
> >> function 'kmemleak_ignore' [-Werror=implicit-function-declaration]
> >> [ 148s] 106 | kmemleak_ignore(var);
> >> [ 148s] | ^~~~~~~~~~~~~~~
> >>
> >
> > Ah yes, thanks for the report. I will add the include to the patch.
> >
> >
>
> Is this necessary if CONFIG_DEBUG_KMEMLEAK is not enabled in the kernel
> config? e.g. should there be an #ifdef CONFIG_DEBUG_KMEMLEAK somewhere
> in there?
kmemleak_ignore() is a noop if CONFIG_DEBUG_KMEMLEAK is not set. See
include/linux/kmemleak.h. Thus no extra condition is needed here.
--
Oleksandr Natalenko (post-factum)
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2020-11-27 16:59 UTC | newest]
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2020-11-25 7:53 [PATCH] efivarfs: revert "fix memory leak in efivarfs_create()" Ard Biesheuvel
2020-11-25 8:05 ` Oleksandr Natalenko
2020-11-25 8:05 ` Ard Biesheuvel
2020-11-25 8:25 ` Greg Kroah-Hartman
2020-11-25 10:27 ` Oleksandr Natalenko
2020-11-25 10:28 ` Ard Biesheuvel
2020-11-27 16:50 ` Jonathon Fernyhough
2020-11-27 16:58 ` Ard Biesheuvel
2020-11-27 16:59 ` Oleksandr Natalenko
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