| Message ID | 150040226878.1216.15454073908001325566.stgit@magnolia (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Headers | show |
On Tue, Jul 18, 2017 at 11:24:28AM -0700, Darrick J. Wong wrote: > From: Darrick J. Wong <darrick.wong@oracle.com> > > In some circumstances, _alloc_read_agf can return an error code of zero > but also a null AGF buffer pointer. Check for this and jump out. > It looks like this is only possible in trylock cases. Otherwise (and unless I'm missing something), it should always return a buffer or error. This is circuitous regardless and so seems fine if it shuts up a coverity warning: Reviewed-by: Brian Foster <bfoster@redhat.com> > Fixes-coverity-id: 1415250 > Fixes-coverity-id: 1415320 > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> > --- > fs/xfs/libxfs/xfs_refcount.c | 4 ++++ > fs/xfs/xfs_reflink.c | 2 ++ > 2 files changed, 6 insertions(+) > > > diff --git a/fs/xfs/libxfs/xfs_refcount.c b/fs/xfs/libxfs/xfs_refcount.c > index 900ea23..45b1c3b 100644 > --- a/fs/xfs/libxfs/xfs_refcount.c > +++ b/fs/xfs/libxfs/xfs_refcount.c > @@ -1638,6 +1638,10 @@ xfs_refcount_recover_cow_leftovers( > error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp); > if (error) > goto out_trans; > + if (!agbp) { > + error = -ENOMEM; > + goto out_trans; > + } > cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno, NULL); > > /* Find all the leftover CoW staging extents. */ > diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c > index d9b3d57..f45fbf0 100644 > --- a/fs/xfs/xfs_reflink.c > +++ b/fs/xfs/xfs_reflink.c > @@ -170,6 +170,8 @@ xfs_reflink_find_shared( > error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp); > if (error) > return error; > + if (!agbp) > + return -ENOMEM; > > cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno, NULL); > > > -- > 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 Wed, Jul 19, 2017 at 09:20:32AM -0400, Brian Foster wrote: > On Tue, Jul 18, 2017 at 11:24:28AM -0700, Darrick J. Wong wrote: > > From: Darrick J. Wong <darrick.wong@oracle.com> > > > > In some circumstances, _alloc_read_agf can return an error code of zero > > but also a null AGF buffer pointer. Check for this and jump out. > > > > It looks like this is only possible in trylock cases. Otherwise (and > unless I'm missing something), it should always return a buffer or > error. > > This is circuitous regardless and so seems fine if it shuts up a > coverity warning: <shrug> I argue it's also defensive, in case we ever /do/ change the semantics to allow more "zero return and no bp" cases, then these parts won't suddenly start blowing up. I think the Coverity analysis is just plain wrong (it claims that we can somehow corrupt return values to end up with a zero return having started with -EIO) but I did spot the trylock case and figured we could be defensive about that. --D > Reviewed-by: Brian Foster <bfoster@redhat.com> > > > Fixes-coverity-id: 1415250 > > Fixes-coverity-id: 1415320 > > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> > > --- > > fs/xfs/libxfs/xfs_refcount.c | 4 ++++ > > fs/xfs/xfs_reflink.c | 2 ++ > > 2 files changed, 6 insertions(+) > > > > > > diff --git a/fs/xfs/libxfs/xfs_refcount.c b/fs/xfs/libxfs/xfs_refcount.c > > index 900ea23..45b1c3b 100644 > > --- a/fs/xfs/libxfs/xfs_refcount.c > > +++ b/fs/xfs/libxfs/xfs_refcount.c > > @@ -1638,6 +1638,10 @@ xfs_refcount_recover_cow_leftovers( > > error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp); > > if (error) > > goto out_trans; > > + if (!agbp) { > > + error = -ENOMEM; > > + goto out_trans; > > + } > > cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno, NULL); > > > > /* Find all the leftover CoW staging extents. */ > > diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c > > index d9b3d57..f45fbf0 100644 > > --- a/fs/xfs/xfs_reflink.c > > +++ b/fs/xfs/xfs_reflink.c > > @@ -170,6 +170,8 @@ xfs_reflink_find_shared( > > error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp); > > if (error) > > return error; > > + if (!agbp) > > + return -ENOMEM; > > > > cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno, NULL); > > > > > > -- > > 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/libxfs/xfs_refcount.c b/fs/xfs/libxfs/xfs_refcount.c index 900ea23..45b1c3b 100644 --- a/fs/xfs/libxfs/xfs_refcount.c +++ b/fs/xfs/libxfs/xfs_refcount.c @@ -1638,6 +1638,10 @@ xfs_refcount_recover_cow_leftovers( error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp); if (error) goto out_trans; + if (!agbp) { + error = -ENOMEM; + goto out_trans; + } cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno, NULL); /* Find all the leftover CoW staging extents. */ diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c index d9b3d57..f45fbf0 100644 --- a/fs/xfs/xfs_reflink.c +++ b/fs/xfs/xfs_reflink.c @@ -170,6 +170,8 @@ xfs_reflink_find_shared( error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp); if (error) return error; + if (!agbp) + return -ENOMEM; cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno, NULL);