* [PATCH 1/5] fs, xfs: convert xfs_bui_log_item.bui_refcount from atomic_t to refcount_t
2017-03-01 8:47 [PATCH 0/5] fs, xfs atomic_t to refcount_t conversions version 2 Elena Reshetova
@ 2017-03-01 8:47 ` Elena Reshetova
2017-03-01 8:47 ` [PATCH 2/5] fs, xfs: convert xfs_efi_log_item.efi_refcount " Elena Reshetova
` (3 subsequent siblings)
4 siblings, 0 replies; 9+ messages in thread
From: Elena Reshetova @ 2017-03-01 8:47 UTC (permalink / raw)
To: linux-kernel
Cc: linux-xfs, peterz, gregkh, darrick.wong, david, Elena Reshetova,
Hans Liljestrand, Kees Cook, David Windsor
refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
---
fs/xfs/xfs_bmap_item.c | 4 ++--
fs/xfs/xfs_bmap_item.h | 4 +++-
2 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/fs/xfs/xfs_bmap_item.c b/fs/xfs/xfs_bmap_item.c
index 9bf57c7..33104ad 100644
--- a/fs/xfs/xfs_bmap_item.c
+++ b/fs/xfs/xfs_bmap_item.c
@@ -199,7 +199,7 @@ xfs_bui_init(
buip->bui_format.bui_nextents = XFS_BUI_MAX_FAST_EXTENTS;
buip->bui_format.bui_id = (uintptr_t)(void *)buip;
atomic_set(&buip->bui_next_extent, 0);
- atomic_set(&buip->bui_refcount, 2);
+ refcount_set(&buip->bui_refcount, 2);
return buip;
}
@@ -215,7 +215,7 @@ void
xfs_bui_release(
struct xfs_bui_log_item *buip)
{
- if (atomic_dec_and_test(&buip->bui_refcount)) {
+ if (refcount_dec_and_test(&buip->bui_refcount)) {
xfs_trans_ail_remove(&buip->bui_item, SHUTDOWN_LOG_IO_ERROR);
xfs_bui_item_free(buip);
}
diff --git a/fs/xfs/xfs_bmap_item.h b/fs/xfs/xfs_bmap_item.h
index c867daa..988a6ae 100644
--- a/fs/xfs/xfs_bmap_item.h
+++ b/fs/xfs/xfs_bmap_item.h
@@ -20,6 +20,8 @@
#ifndef __XFS_BMAP_ITEM_H__
#define __XFS_BMAP_ITEM_H__
+#include <linux/refcount.h>
+
/*
* There are (currently) two pairs of bmap btree redo item types: map & unmap.
* The common abbreviations for these are BUI (bmap update intent) and BUD
@@ -61,7 +63,7 @@ struct kmem_zone;
*/
struct xfs_bui_log_item {
struct xfs_log_item bui_item;
- atomic_t bui_refcount;
+ refcount_t bui_refcount;
atomic_t bui_next_extent;
unsigned long bui_flags; /* misc flags */
struct xfs_bui_log_format bui_format;
--
2.7.4
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH 2/5] fs, xfs: convert xfs_efi_log_item.efi_refcount from atomic_t to refcount_t
2017-03-01 8:47 [PATCH 0/5] fs, xfs atomic_t to refcount_t conversions version 2 Elena Reshetova
2017-03-01 8:47 ` [PATCH 1/5] fs, xfs: convert xfs_bui_log_item.bui_refcount from atomic_t to refcount_t Elena Reshetova
@ 2017-03-01 8:47 ` Elena Reshetova
2017-03-01 8:47 ` [PATCH 3/5] fs, xfs: convert xlog_ticket.t_ref " Elena Reshetova
` (2 subsequent siblings)
4 siblings, 0 replies; 9+ messages in thread
From: Elena Reshetova @ 2017-03-01 8:47 UTC (permalink / raw)
To: linux-kernel
Cc: linux-xfs, peterz, gregkh, darrick.wong, david, Elena Reshetova,
Hans Liljestrand, Kees Cook, David Windsor
refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
---
fs/xfs/xfs_extfree_item.c | 4 ++--
fs/xfs/xfs_extfree_item.h | 4 +++-
2 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/fs/xfs/xfs_extfree_item.c b/fs/xfs/xfs_extfree_item.c
index d7bc149..4e0acf0 100644
--- a/fs/xfs/xfs_extfree_item.c
+++ b/fs/xfs/xfs_extfree_item.c
@@ -220,7 +220,7 @@ xfs_efi_init(
efip->efi_format.efi_nextents = nextents;
efip->efi_format.efi_id = (uintptr_t)(void *)efip;
atomic_set(&efip->efi_next_extent, 0);
- atomic_set(&efip->efi_refcount, 2);
+ refcount_set(&efip->efi_refcount, 2);
return efip;
}
@@ -290,7 +290,7 @@ void
xfs_efi_release(
struct xfs_efi_log_item *efip)
{
- if (atomic_dec_and_test(&efip->efi_refcount)) {
+ if (refcount_dec_and_test(&efip->efi_refcount)) {
xfs_trans_ail_remove(&efip->efi_item, SHUTDOWN_LOG_IO_ERROR);
xfs_efi_item_free(efip);
}
diff --git a/fs/xfs/xfs_extfree_item.h b/fs/xfs/xfs_extfree_item.h
index a32c794..e6da63d 100644
--- a/fs/xfs/xfs_extfree_item.h
+++ b/fs/xfs/xfs_extfree_item.h
@@ -18,6 +18,8 @@
#ifndef __XFS_EXTFREE_ITEM_H__
#define __XFS_EXTFREE_ITEM_H__
+#include <linux/refcount.h>
+
/* kernel only EFI/EFD definitions */
struct xfs_mount;
@@ -64,7 +66,7 @@ struct kmem_zone;
*/
typedef struct xfs_efi_log_item {
xfs_log_item_t efi_item;
- atomic_t efi_refcount;
+ refcount_t efi_refcount;
atomic_t efi_next_extent;
unsigned long efi_flags; /* misc flags */
xfs_efi_log_format_t efi_format;
--
2.7.4
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH 3/5] fs, xfs: convert xlog_ticket.t_ref from atomic_t to refcount_t
2017-03-01 8:47 [PATCH 0/5] fs, xfs atomic_t to refcount_t conversions version 2 Elena Reshetova
2017-03-01 8:47 ` [PATCH 1/5] fs, xfs: convert xfs_bui_log_item.bui_refcount from atomic_t to refcount_t Elena Reshetova
2017-03-01 8:47 ` [PATCH 2/5] fs, xfs: convert xfs_efi_log_item.efi_refcount " Elena Reshetova
@ 2017-03-01 8:47 ` Elena Reshetova
2017-03-01 8:47 ` [PATCH 4/5] fs, xfs: convert xfs_cui_log_item.cui_refcount " Elena Reshetova
2017-03-01 8:47 ` [PATCH 5/5] fs, xfs: convert xfs_rui_log_item.rui_refcount " Elena Reshetova
4 siblings, 0 replies; 9+ messages in thread
From: Elena Reshetova @ 2017-03-01 8:47 UTC (permalink / raw)
To: linux-kernel
Cc: linux-xfs, peterz, gregkh, darrick.wong, david, Elena Reshetova,
Hans Liljestrand, Kees Cook, David Windsor
refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
---
fs/xfs/xfs_log.c | 10 +++++-----
fs/xfs/xfs_log_priv.h | 4 +++-
2 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index b1469f0..c127fa0 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -3500,8 +3500,8 @@ void
xfs_log_ticket_put(
xlog_ticket_t *ticket)
{
- ASSERT(atomic_read(&ticket->t_ref) > 0);
- if (atomic_dec_and_test(&ticket->t_ref))
+ ASSERT(refcount_read(&ticket->t_ref) > 0);
+ if (refcount_dec_and_test(&ticket->t_ref))
kmem_zone_free(xfs_log_ticket_zone, ticket);
}
@@ -3509,8 +3509,8 @@ xlog_ticket_t *
xfs_log_ticket_get(
xlog_ticket_t *ticket)
{
- ASSERT(atomic_read(&ticket->t_ref) > 0);
- atomic_inc(&ticket->t_ref);
+ ASSERT(refcount_read(&ticket->t_ref) > 0);
+ refcount_inc(&ticket->t_ref);
return ticket;
}
@@ -3632,7 +3632,7 @@ xlog_ticket_alloc(
unit_res = xfs_log_calc_unit_res(log->l_mp, unit_bytes);
- atomic_set(&tic->t_ref, 1);
+ refcount_set(&tic->t_ref, 1);
tic->t_task = current;
INIT_LIST_HEAD(&tic->t_queue);
tic->t_unit_res = unit_res;
diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index c2604a5..279afce 100644
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -18,6 +18,8 @@
#ifndef __XFS_LOG_PRIV_H__
#define __XFS_LOG_PRIV_H__
+#include <linux/refcount.h>
+
struct xfs_buf;
struct xlog;
struct xlog_ticket;
@@ -168,7 +170,7 @@ typedef struct xlog_ticket {
struct list_head t_queue; /* reserve/write queue */
struct task_struct *t_task; /* task that owns this ticket */
xlog_tid_t t_tid; /* transaction identifier : 4 */
- atomic_t t_ref; /* ticket reference count : 4 */
+ refcount_t t_ref; /* ticket reference count : 4 */
int t_curr_res; /* current reservation in bytes : 4 */
int t_unit_res; /* unit reservation in bytes : 4 */
char t_ocnt; /* original count : 1 */
--
2.7.4
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH 4/5] fs, xfs: convert xfs_cui_log_item.cui_refcount from atomic_t to refcount_t
2017-03-01 8:47 [PATCH 0/5] fs, xfs atomic_t to refcount_t conversions version 2 Elena Reshetova
` (2 preceding siblings ...)
2017-03-01 8:47 ` [PATCH 3/5] fs, xfs: convert xlog_ticket.t_ref " Elena Reshetova
@ 2017-03-01 8:47 ` Elena Reshetova
2017-03-06 19:14 ` Darrick J. Wong
2017-03-01 8:47 ` [PATCH 5/5] fs, xfs: convert xfs_rui_log_item.rui_refcount " Elena Reshetova
4 siblings, 1 reply; 9+ messages in thread
From: Elena Reshetova @ 2017-03-01 8:47 UTC (permalink / raw)
To: linux-kernel
Cc: linux-xfs, peterz, gregkh, darrick.wong, david, Elena Reshetova,
Hans Liljestrand, Kees Cook, David Windsor
refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
---
fs/xfs/xfs_refcount_item.c | 4 ++--
fs/xfs/xfs_refcount_item.h | 4 +++-
2 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/fs/xfs/xfs_refcount_item.c b/fs/xfs/xfs_refcount_item.c
index 6e4c744..61bc570 100644
--- a/fs/xfs/xfs_refcount_item.c
+++ b/fs/xfs/xfs_refcount_item.c
@@ -205,7 +205,7 @@ xfs_cui_init(
cuip->cui_format.cui_nextents = nextents;
cuip->cui_format.cui_id = (uintptr_t)(void *)cuip;
atomic_set(&cuip->cui_next_extent, 0);
- atomic_set(&cuip->cui_refcount, 2);
+ refcount_set(&cuip->cui_refcount, 2);
return cuip;
}
@@ -221,7 +221,7 @@ void
xfs_cui_release(
struct xfs_cui_log_item *cuip)
{
- if (atomic_dec_and_test(&cuip->cui_refcount)) {
+ if (refcount_dec_and_test(&cuip->cui_refcount)) {
xfs_trans_ail_remove(&cuip->cui_item, SHUTDOWN_LOG_IO_ERROR);
xfs_cui_item_free(cuip);
}
diff --git a/fs/xfs/xfs_refcount_item.h b/fs/xfs/xfs_refcount_item.h
index 5b74ddd..7f23ff8 100644
--- a/fs/xfs/xfs_refcount_item.h
+++ b/fs/xfs/xfs_refcount_item.h
@@ -20,6 +20,8 @@
#ifndef __XFS_REFCOUNT_ITEM_H__
#define __XFS_REFCOUNT_ITEM_H__
+#include <linux/refcount.h>
+
/*
* There are (currently) two pairs of refcount btree redo item types:
* increase and decrease. The log items for these are CUI (refcount
@@ -63,7 +65,7 @@ struct kmem_zone;
*/
struct xfs_cui_log_item {
struct xfs_log_item cui_item;
- atomic_t cui_refcount;
+ refcount_t cui_refcount;
atomic_t cui_next_extent;
unsigned long cui_flags; /* misc flags */
struct xfs_cui_log_format cui_format;
--
2.7.4
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH 4/5] fs, xfs: convert xfs_cui_log_item.cui_refcount from atomic_t to refcount_t
2017-03-01 8:47 ` [PATCH 4/5] fs, xfs: convert xfs_cui_log_item.cui_refcount " Elena Reshetova
@ 2017-03-06 19:14 ` Darrick J. Wong
2017-03-07 17:33 ` Reshetova, Elena
0 siblings, 1 reply; 9+ messages in thread
From: Darrick J. Wong @ 2017-03-06 19:14 UTC (permalink / raw)
To: Elena Reshetova
Cc: linux-kernel, linux-xfs, peterz, gregkh, david, Hans Liljestrand,
Kees Cook, David Windsor
On Wed, Mar 01, 2017 at 10:47:39AM +0200, Elena Reshetova wrote:
> refcount_t type and corresponding API should be
> used instead of atomic_t when the variable is used as
> a reference counter. This allows to avoid accidental
> refcounter overflows that might lead to use-after-free
> situations.
>
> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
> Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> Signed-off-by: David Windsor <dwindsor@gmail.com>
> ---
> fs/xfs/xfs_refcount_item.c | 4 ++--
> fs/xfs/xfs_refcount_item.h | 4 +++-
> 2 files changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/fs/xfs/xfs_refcount_item.c b/fs/xfs/xfs_refcount_item.c
> index 6e4c744..61bc570 100644
> --- a/fs/xfs/xfs_refcount_item.c
> +++ b/fs/xfs/xfs_refcount_item.c
> @@ -205,7 +205,7 @@ xfs_cui_init(
> cuip->cui_format.cui_nextents = nextents;
> cuip->cui_format.cui_id = (uintptr_t)(void *)cuip;
> atomic_set(&cuip->cui_next_extent, 0);
> - atomic_set(&cuip->cui_refcount, 2);
> + refcount_set(&cuip->cui_refcount, 2);
I'm assuming the refcount design is ok with the log item refcounts
starting at 2 and marching down to zero? The code seems to be
fine with it; I just want to make sure everyone's ok with supporting
this use case.
> return cuip;
> }
> @@ -221,7 +221,7 @@ void
> xfs_cui_release(
> struct xfs_cui_log_item *cuip)
> {
> - if (atomic_dec_and_test(&cuip->cui_refcount)) {
> + if (refcount_dec_and_test(&cuip->cui_refcount)) {
I suppose it's useful to have refcount_dec_and_test complain loudly if
we ever have a dangling pointer... Friday I was chasing a possible
use-after-free of the EFI items in generic/388.
> xfs_trans_ail_remove(&cuip->cui_item, SHUTDOWN_LOG_IO_ERROR);
> xfs_cui_item_free(cuip);
> }
> diff --git a/fs/xfs/xfs_refcount_item.h b/fs/xfs/xfs_refcount_item.h
> index 5b74ddd..7f23ff8 100644
> --- a/fs/xfs/xfs_refcount_item.h
> +++ b/fs/xfs/xfs_refcount_item.h
> @@ -20,6 +20,8 @@
> #ifndef __XFS_REFCOUNT_ITEM_H__
> #define __XFS_REFCOUNT_ITEM_H__
>
> +#include <linux/refcount.h>
I still think this include should go in xfs_linux.h, the same as most of
the other linux/*.h includes in XFS.
--D
> +
> /*
> * There are (currently) two pairs of refcount btree redo item types:
> * increase and decrease. The log items for these are CUI (refcount
> @@ -63,7 +65,7 @@ struct kmem_zone;
> */
> struct xfs_cui_log_item {
> struct xfs_log_item cui_item;
> - atomic_t cui_refcount;
> + refcount_t cui_refcount;
> atomic_t cui_next_extent;
> unsigned long cui_flags; /* misc flags */
> struct xfs_cui_log_format cui_format;
> --
> 2.7.4
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 9+ messages in thread
* RE: [PATCH 4/5] fs, xfs: convert xfs_cui_log_item.cui_refcount from atomic_t to refcount_t
2017-03-06 19:14 ` Darrick J. Wong
@ 2017-03-07 17:33 ` Reshetova, Elena
2017-03-07 20:30 ` Darrick J. Wong
0 siblings, 1 reply; 9+ messages in thread
From: Reshetova, Elena @ 2017-03-07 17:33 UTC (permalink / raw)
To: Darrick J. Wong
Cc: linux-kernel, linux-xfs, peterz, gregkh, david, Hans Liljestrand,
Kees Cook, David Windsor
> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
> > Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
> > Signed-off-by: Kees Cook <keescook@chromium.org>
> > Signed-off-by: David Windsor <dwindsor@gmail.com>
> > ---
> > fs/xfs/xfs_refcount_item.c | 4 ++--
> > fs/xfs/xfs_refcount_item.h | 4 +++-
> > 2 files changed, 5 insertions(+), 3 deletions(-)
> >
> > diff --git a/fs/xfs/xfs_refcount_item.c b/fs/xfs/xfs_refcount_item.c
> > index 6e4c744..61bc570 100644
> > --- a/fs/xfs/xfs_refcount_item.c
> > +++ b/fs/xfs/xfs_refcount_item.c
> > @@ -205,7 +205,7 @@ xfs_cui_init(
> > cuip->cui_format.cui_nextents = nextents;
> > cuip->cui_format.cui_id = (uintptr_t)(void *)cuip;
> > atomic_set(&cuip->cui_next_extent, 0);
> > - atomic_set(&cuip->cui_refcount, 2);
> > + refcount_set(&cuip->cui_refcount, 2);
>
> I'm assuming the refcount design is ok with the log item refcounts
> starting at 2 and marching down to zero? The code seems to be
> fine with it; I just want to make sure everyone's ok with supporting
> this use case.
Yes, as soon as it doesn't go beyond 0 or starting to increment again after reaching zero.
>
> > return cuip;
> > }
> > @@ -221,7 +221,7 @@ void
> > xfs_cui_release(
> > struct xfs_cui_log_item *cuip)
> > {
> > - if (atomic_dec_and_test(&cuip->cui_refcount)) {
> > + if (refcount_dec_and_test(&cuip->cui_refcount)) {
>
> I suppose it's useful to have refcount_dec_and_test complain loudly if
> we ever have a dangling pointer... Friday I was chasing a possible
> use-after-free of the EFI items in generic/388.
Currently it complains with WARN if it finds itself decrementing from zero.
There is patch in RFC stage also that would make it configurable: complain with WARN or complain/abort with BUG.
>
> > xfs_trans_ail_remove(&cuip->cui_item,
> SHUTDOWN_LOG_IO_ERROR);
> > xfs_cui_item_free(cuip);
> > }
> > diff --git a/fs/xfs/xfs_refcount_item.h b/fs/xfs/xfs_refcount_item.h
> > index 5b74ddd..7f23ff8 100644
> > --- a/fs/xfs/xfs_refcount_item.h
> > +++ b/fs/xfs/xfs_refcount_item.h
> > @@ -20,6 +20,8 @@
> > #ifndef __XFS_REFCOUNT_ITEM_H__
> > #define __XFS_REFCOUNT_ITEM_H__
> >
> > +#include <linux/refcount.h>
>
> I still think this include should go in xfs_linux.h, the same as most of
> the other linux/*.h includes in XFS.
Oh, very sorry, I forgot this one. Got too much focused on testing :(
Do you want me to resend with this change or can you take it in and do this small fix yourself?
Best Regards,
Elena.
>
> --D
>
> > +
> > /*
> > * There are (currently) two pairs of refcount btree redo item types:
> > * increase and decrease. The log items for these are CUI (refcount
> > @@ -63,7 +65,7 @@ struct kmem_zone;
> > */
> > struct xfs_cui_log_item {
> > struct xfs_log_item cui_item;
> > - atomic_t cui_refcount;
> > + refcount_t cui_refcount;
> > atomic_t cui_next_extent;
> > unsigned long cui_flags; /* misc
> flags */
> > struct xfs_cui_log_format cui_format;
> > --
> > 2.7.4
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH 4/5] fs, xfs: convert xfs_cui_log_item.cui_refcount from atomic_t to refcount_t
2017-03-07 17:33 ` Reshetova, Elena
@ 2017-03-07 20:30 ` Darrick J. Wong
0 siblings, 0 replies; 9+ messages in thread
From: Darrick J. Wong @ 2017-03-07 20:30 UTC (permalink / raw)
To: Reshetova, Elena
Cc: linux-kernel, linux-xfs, peterz, gregkh, david, Hans Liljestrand,
Kees Cook, David Windsor
On Tue, Mar 07, 2017 at 05:33:14PM +0000, Reshetova, Elena wrote:
> > Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
> > > Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
> > > Signed-off-by: Kees Cook <keescook@chromium.org>
> > > Signed-off-by: David Windsor <dwindsor@gmail.com>
> > > ---
> > > fs/xfs/xfs_refcount_item.c | 4 ++--
> > > fs/xfs/xfs_refcount_item.h | 4 +++-
> > > 2 files changed, 5 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/fs/xfs/xfs_refcount_item.c b/fs/xfs/xfs_refcount_item.c
> > > index 6e4c744..61bc570 100644
> > > --- a/fs/xfs/xfs_refcount_item.c
> > > +++ b/fs/xfs/xfs_refcount_item.c
> > > @@ -205,7 +205,7 @@ xfs_cui_init(
> > > cuip->cui_format.cui_nextents = nextents;
> > > cuip->cui_format.cui_id = (uintptr_t)(void *)cuip;
> > > atomic_set(&cuip->cui_next_extent, 0);
> > > - atomic_set(&cuip->cui_refcount, 2);
> > > + refcount_set(&cuip->cui_refcount, 2);
> >
> > I'm assuming the refcount design is ok with the log item refcounts
> > starting at 2 and marching down to zero? The code seems to be
> > fine with it; I just want to make sure everyone's ok with supporting
> > this use case.
>
> Yes, as soon as it doesn't go beyond 0 or starting to increment again after reaching zero.
Ok, good.
> >
> > > return cuip;
> > > }
> > > @@ -221,7 +221,7 @@ void
> > > xfs_cui_release(
> > > struct xfs_cui_log_item *cuip)
> > > {
> > > - if (atomic_dec_and_test(&cuip->cui_refcount)) {
> > > + if (refcount_dec_and_test(&cuip->cui_refcount)) {
> >
> > I suppose it's useful to have refcount_dec_and_test complain loudly if
> > we ever have a dangling pointer... Friday I was chasing a possible
> > use-after-free of the EFI items in generic/388.
>
> Currently it complains with WARN if it finds itself decrementing from zero.
> There is patch in RFC stage also that would make it configurable: complain with WARN or complain/abort with BUG.
>
> >
> > > xfs_trans_ail_remove(&cuip->cui_item,
> > SHUTDOWN_LOG_IO_ERROR);
> > > xfs_cui_item_free(cuip);
> > > }
> > > diff --git a/fs/xfs/xfs_refcount_item.h b/fs/xfs/xfs_refcount_item.h
> > > index 5b74ddd..7f23ff8 100644
> > > --- a/fs/xfs/xfs_refcount_item.h
> > > +++ b/fs/xfs/xfs_refcount_item.h
> > > @@ -20,6 +20,8 @@
> > > #ifndef __XFS_REFCOUNT_ITEM_H__
> > > #define __XFS_REFCOUNT_ITEM_H__
> > >
> > > +#include <linux/refcount.h>
> >
> > I still think this include should go in xfs_linux.h, the same as most of
> > the other linux/*.h includes in XFS.
>
> Oh, very sorry, I forgot this one. Got too much focused on testing :(
> Do you want me to resend with this change or can you take it in and do this small fix yourself?
Since the comment applies to all the patches, please resend the series
with all the patches fixed up.
--D
>
> Best Regards,
> Elena.
>
>
> >
> > --D
> >
> > > +
> > > /*
> > > * There are (currently) two pairs of refcount btree redo item types:
> > > * increase and decrease. The log items for these are CUI (refcount
> > > @@ -63,7 +65,7 @@ struct kmem_zone;
> > > */
> > > struct xfs_cui_log_item {
> > > struct xfs_log_item cui_item;
> > > - atomic_t cui_refcount;
> > > + refcount_t cui_refcount;
> > > atomic_t cui_next_extent;
> > > unsigned long cui_flags; /* misc
> > flags */
> > > struct xfs_cui_log_format cui_format;
> > > --
> > > 2.7.4
> > >
> > > --
> > > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> > > the body of a message to majordomo@vger.kernel.org
> > > More majordomo info at http://vger.kernel.org/majordomo-info.html
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH 5/5] fs, xfs: convert xfs_rui_log_item.rui_refcount from atomic_t to refcount_t
2017-03-01 8:47 [PATCH 0/5] fs, xfs atomic_t to refcount_t conversions version 2 Elena Reshetova
` (3 preceding siblings ...)
2017-03-01 8:47 ` [PATCH 4/5] fs, xfs: convert xfs_cui_log_item.cui_refcount " Elena Reshetova
@ 2017-03-01 8:47 ` Elena Reshetova
4 siblings, 0 replies; 9+ messages in thread
From: Elena Reshetova @ 2017-03-01 8:47 UTC (permalink / raw)
To: linux-kernel
Cc: linux-xfs, peterz, gregkh, darrick.wong, david, Elena Reshetova,
Hans Liljestrand, Kees Cook, David Windsor
refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
---
fs/xfs/xfs_rmap_item.c | 4 ++--
fs/xfs/xfs_rmap_item.h | 4 +++-
2 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/fs/xfs/xfs_rmap_item.c b/fs/xfs/xfs_rmap_item.c
index 73c8278..5e1664a 100644
--- a/fs/xfs/xfs_rmap_item.c
+++ b/fs/xfs/xfs_rmap_item.c
@@ -204,7 +204,7 @@ xfs_rui_init(
ruip->rui_format.rui_nextents = nextents;
ruip->rui_format.rui_id = (uintptr_t)(void *)ruip;
atomic_set(&ruip->rui_next_extent, 0);
- atomic_set(&ruip->rui_refcount, 2);
+ refcount_set(&ruip->rui_refcount, 2);
return ruip;
}
@@ -243,7 +243,7 @@ void
xfs_rui_release(
struct xfs_rui_log_item *ruip)
{
- if (atomic_dec_and_test(&ruip->rui_refcount)) {
+ if (refcount_dec_and_test(&ruip->rui_refcount)) {
xfs_trans_ail_remove(&ruip->rui_item, SHUTDOWN_LOG_IO_ERROR);
xfs_rui_item_free(ruip);
}
diff --git a/fs/xfs/xfs_rmap_item.h b/fs/xfs/xfs_rmap_item.h
index 340c968..2529a35 100644
--- a/fs/xfs/xfs_rmap_item.h
+++ b/fs/xfs/xfs_rmap_item.h
@@ -20,6 +20,8 @@
#ifndef __XFS_RMAP_ITEM_H__
#define __XFS_RMAP_ITEM_H__
+#include <linux/refcount.h>
+
/*
* There are (currently) three pairs of rmap btree redo item types: map, unmap,
* and convert. The common abbreviations for these are RUI (rmap update
@@ -64,7 +66,7 @@ struct kmem_zone;
*/
struct xfs_rui_log_item {
struct xfs_log_item rui_item;
- atomic_t rui_refcount;
+ refcount_t rui_refcount;
atomic_t rui_next_extent;
unsigned long rui_flags; /* misc flags */
struct xfs_rui_log_format rui_format;
--
2.7.4
^ permalink raw reply related [flat|nested] 9+ messages in thread