| Message ID | 1488358060-693-5-git-send-email-elena.reshetova@intel.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
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 -- 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
> 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 -- 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
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 -- 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
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;