| Message ID | 20190206160107.63672-1-bfoster@redhat.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | xfs: fix use after free in buf log item unlock assert | expand |
On Wed, Feb 06, 2019 at 11:01:07AM -0500, Brian Foster wrote: > The xfs_buf_log_item ->iop_unlock() callback asserts that the buffer > is unlocked when either non-stale or aborted. This assert occurs > after the bli refcount has been dropped and the log item potentially > freed. The aborted check is thus a potential use after free. This > problem has been reproduced with KASAN enabled via generic/475. > > Fix up xfs_buf_item_unlock() to query aborted state before the bli > reference is dropped to prevent a potential use after free. > > Signed-off-by: Brian Foster <bfoster@redhat.com> Seems reasonable, Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> --D > --- > fs/xfs/xfs_buf_item.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c > index 010db5f8fb00..65b32acfa0f6 100644 > --- a/fs/xfs/xfs_buf_item.c > +++ b/fs/xfs/xfs_buf_item.c > @@ -605,6 +605,8 @@ xfs_buf_item_unlock( > #if defined(DEBUG) || defined(XFS_WARN) > bool ordered = bip->bli_flags & XFS_BLI_ORDERED; > bool dirty = bip->bli_flags & XFS_BLI_DIRTY; > + bool aborted = test_bit(XFS_LI_ABORTED, > + &lip->li_flags); > #endif > > trace_xfs_buf_item_unlock(bip); > @@ -633,7 +635,7 @@ xfs_buf_item_unlock( > released = xfs_buf_item_put(bip); > if (hold || (stale && !released)) > return; > - ASSERT(!stale || test_bit(XFS_LI_ABORTED, &lip->li_flags)); > + ASSERT(!stale || aborted); > xfs_buf_relse(bp); > } > > -- > 2.17.2 >
On Wed, Feb 06, 2019 at 11:01:07AM -0500, Brian Foster wrote: > The xfs_buf_log_item ->iop_unlock() callback asserts that the buffer > is unlocked when either non-stale or aborted. This assert occurs > after the bli refcount has been dropped and the log item potentially > freed. The aborted check is thus a potential use after free. This > problem has been reproduced with KASAN enabled via generic/475. > > Fix up xfs_buf_item_unlock() to query aborted state before the bli > reference is dropped to prevent a potential use after free. > > Signed-off-by: Brian Foster <bfoster@redhat.com> > --- Ping on this one.. looks like it was reviewed and maybe fell through the cracks? Brian > fs/xfs/xfs_buf_item.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c > index 010db5f8fb00..65b32acfa0f6 100644 > --- a/fs/xfs/xfs_buf_item.c > +++ b/fs/xfs/xfs_buf_item.c > @@ -605,6 +605,8 @@ xfs_buf_item_unlock( > #if defined(DEBUG) || defined(XFS_WARN) > bool ordered = bip->bli_flags & XFS_BLI_ORDERED; > bool dirty = bip->bli_flags & XFS_BLI_DIRTY; > + bool aborted = test_bit(XFS_LI_ABORTED, > + &lip->li_flags); > #endif > > trace_xfs_buf_item_unlock(bip); > @@ -633,7 +635,7 @@ xfs_buf_item_unlock( > released = xfs_buf_item_put(bip); > if (hold || (stale && !released)) > return; > - ASSERT(!stale || test_bit(XFS_LI_ABORTED, &lip->li_flags)); > + ASSERT(!stale || aborted); > xfs_buf_relse(bp); > } > > -- > 2.17.2 >
On Fri, Mar 29, 2019 at 10:03:28AM -0400, Brian Foster wrote: > On Wed, Feb 06, 2019 at 11:01:07AM -0500, Brian Foster wrote: > > The xfs_buf_log_item ->iop_unlock() callback asserts that the buffer > > is unlocked when either non-stale or aborted. This assert occurs > > after the bli refcount has been dropped and the log item potentially > > freed. The aborted check is thus a potential use after free. This > > problem has been reproduced with KASAN enabled via generic/475. > > > > Fix up xfs_buf_item_unlock() to query aborted state before the bli > > reference is dropped to prevent a potential use after free. > > > > Signed-off-by: Brian Foster <bfoster@redhat.com> > > --- > > Ping on this one.. looks like it was reviewed and maybe fell through the > cracks? Yep. Spreadsheet says it's in 5.0-rc6, and ... totally not upstream. :( Sorry about that. --D > Brian > > > fs/xfs/xfs_buf_item.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c > > index 010db5f8fb00..65b32acfa0f6 100644 > > --- a/fs/xfs/xfs_buf_item.c > > +++ b/fs/xfs/xfs_buf_item.c > > @@ -605,6 +605,8 @@ xfs_buf_item_unlock( > > #if defined(DEBUG) || defined(XFS_WARN) > > bool ordered = bip->bli_flags & XFS_BLI_ORDERED; > > bool dirty = bip->bli_flags & XFS_BLI_DIRTY; > > + bool aborted = test_bit(XFS_LI_ABORTED, > > + &lip->li_flags); > > #endif > > > > trace_xfs_buf_item_unlock(bip); > > @@ -633,7 +635,7 @@ xfs_buf_item_unlock( > > released = xfs_buf_item_put(bip); > > if (hold || (stale && !released)) > > return; > > - ASSERT(!stale || test_bit(XFS_LI_ABORTED, &lip->li_flags)); > > + ASSERT(!stale || aborted); > > xfs_buf_relse(bp); > > } > > > > -- > > 2.17.2 > >
diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c index 010db5f8fb00..65b32acfa0f6 100644 --- a/fs/xfs/xfs_buf_item.c +++ b/fs/xfs/xfs_buf_item.c @@ -605,6 +605,8 @@ xfs_buf_item_unlock( #if defined(DEBUG) || defined(XFS_WARN) bool ordered = bip->bli_flags & XFS_BLI_ORDERED; bool dirty = bip->bli_flags & XFS_BLI_DIRTY; + bool aborted = test_bit(XFS_LI_ABORTED, + &lip->li_flags); #endif trace_xfs_buf_item_unlock(bip); @@ -633,7 +635,7 @@ xfs_buf_item_unlock( released = xfs_buf_item_put(bip); if (hold || (stale && !released)) return; - ASSERT(!stale || test_bit(XFS_LI_ABORTED, &lip->li_flags)); + ASSERT(!stale || aborted); xfs_buf_relse(bp); }
The xfs_buf_log_item ->iop_unlock() callback asserts that the buffer is unlocked when either non-stale or aborted. This assert occurs after the bli refcount has been dropped and the log item potentially freed. The aborted check is thus a potential use after free. This problem has been reproduced with KASAN enabled via generic/475. Fix up xfs_buf_item_unlock() to query aborted state before the bli reference is dropped to prevent a potential use after free. Signed-off-by: Brian Foster <bfoster@redhat.com> --- fs/xfs/xfs_buf_item.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)