This is important so reading /proc/<pid>/{uid_map,gid_map,projid_map} while
the map is being written does not do strange things.
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
---
kernel/user_namespace.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 563a2981d7c7..4f7e357ac1e2 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -683,11 +683,13 @@ static void *m_start(struct seq_file *seq, loff_t *ppos,
struct uid_gid_map *map)
{
loff_t pos = *ppos;
+ unsigned extents = map->nr_extents;
+ smp_rmb();
- if (pos >= map->nr_extents)
+ if (pos >= extents)
return NULL;
- if (map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS)
+ if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS)
return &map->extent[pos];
return &map->forward[pos];
--
2.14.1
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