libceph: validate OSD extent maps before cursor advance

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net/ceph/osd_client.c:osd_sparse_read() validates that the sparse-read
data length matches the summed extent lengths, but it does not validate
that each OSD-supplied extent is monotonic and lies inside the original
request range. A malformed authenticated OSD reply can advertise a
far-forward nonzero extent offset with a matching data length and make
the client advance the message-data cursor beyond the request buffer.
This reaches the BUG_ON(!*length) assertion in ceph_msg_data_next() from
the client receive path.

Impact: A malicious or compromised authenticated Ceph OSD peer can crash
a kernel Ceph client via a malformed sparse-read reply.

Reject sparse extent maps that overflow, move backwards, overlap, or
extend outside the original sparse-read request before advancing the
cursor.

[ idryomov: perform sparse_extent_map_valid() check a bit earlier,
  in CEPH_SPARSE_READ_DATA_LEN instead of CEPH_SPARSE_READ_DATA_PRE
  state ]

Cc: stable@vger.kernel.org
Fixes: f628d79997 ("libceph: add sparse read support to OSD client")
Assisted-by: Codex:gpt-5-5-xhigh
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

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Michael Bommarito 2026-07-14 07:51:39 -04:00 • committed by Ilya Dryomov

parent d2a8d446a0

commit 9ec08b7499

1 changed files with 30 additions and 0 deletions

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net/ceph/osd_client.c

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