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authorEric Sandeen <sandeen@redhat.com>2017-01-17 11:43:38 -0800
committerDarrick J. Wong <darrick.wong@oracle.com>2017-01-17 11:43:38 -0800
commit657bdfb7f5e68ca5e2ed009ab473c429b0d6af85 (patch)
tree29ed1abcffe747d94c6e26959eed1aaf320c5755
parenta324cbf10a3c67aaa10c9f47f7b5801562925bc2 (diff)
xfs: don't wrap ID in xfs_dq_get_next_id
The GETNEXTQOTA ioctl takes whatever ID is sent in, and looks for the next active quota for an user equal or higher to that ID. But if we are at the maximum ID and then ask for the "next" one, we may wrap back to zero. In this case, userspace may loop forever, because it will start querying again at zero. We'll fix this in userspace as well, but for the kernel, return -ENOENT if we ask for the next quota ID past UINT_MAX so the caller knows to stop. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
-rw-r--r--fs/xfs/xfs_dquot.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
index 7a30b8f11db7..9d06cc30e875 100644
--- a/fs/xfs/xfs_dquot.c
+++ b/fs/xfs/xfs_dquot.c
@@ -710,6 +710,10 @@ xfs_dq_get_next_id(
/* Simple advance */
next_id = *id + 1;
+ /* If we'd wrap past the max ID, stop */
+ if (next_id < *id)
+ return -ENOENT;
+
/* If new ID is within the current chunk, advancing it sufficed */
if (next_id % mp->m_quotainfo->qi_dqperchunk) {
*id = next_id;