6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jérémy Jean <redacted>
commit aedc9053d909508a5f56c3f49f885fc030df4730 upstream.
MDSMap export_targets entries are monitor controlled. check_new_map()
uses each entry as a bit number in a fixed stack bitmap, so a rank
outside the protocol namespace can make set_bit() write past the end of
the array.
Reject ranks outside CEPH_MAX_MDS while decoding the map. Do not
validate against possible_max_rank here because maps may legitimately
reference ranks beyond a temporarily reduced max_mds.
Cc: <redacted>
Fixes: d517b3983dd3 ("ceph: reconnect to the export targets on new mdsmaps")
Signed-off-by: Jérémy Jean <redacted>
Reviewed-by: Alex Markuze <amarkuze@redhat.com>
Signed-off-by: Alex Markuze <amarkuze@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/ceph/mdsmap.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/fs/ceph/mdsmap.c
+++ b/fs/ceph/mdsmap.c
@@ -264,6 +264,10 @@ struct ceph_mdsmap *ceph_mdsmap_decode(s
goto nomem;
for (j = 0; j < num_export_targets; j++) {
target = ceph_decode_32(&pexport_targets);
+ if (target >= CEPH_MAX_MDS) {
+ err = -EIO;
+ goto corrupt;
+ }
info->export_targets[j] = target;
}
} else {