From 9ec08b7499a62c6d4afa93d36ab47a43fcad57d1 Mon Sep 17 00:00:00 2001 From: Michael Bommarito Date: Tue, 14 Jul 2026 07:51:39 -0400 Subject: [PATCH] libceph: validate OSD extent maps before cursor advance 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: f628d7999727 ("libceph: add sparse read support to OSD client") Assisted-by: Codex:gpt-5-5-xhigh Signed-off-by: Michael Bommarito Reviewed-by: Viacheslav Dubeyko Signed-off-by: Ilya Dryomov --- net/ceph/osd_client.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c index 28d76c2f6b3e..f36ce5ae7568 100644 --- a/net/ceph/osd_client.c +++ b/net/ceph/osd_client.c @@ -6,6 +6,7 @@ #include #include #include +#include #include #include #include @@ -5802,6 +5803,31 @@ static inline void convert_extent_map(struct ceph_sparse_read *sr) } #endif +static bool sparse_extent_map_valid(struct ceph_sparse_read *sr) +{ + u64 req_end, pos; + int i; + + if (check_add_overflow(sr->sr_req_off, sr->sr_req_len, &req_end)) + return false; + + pos = sr->sr_req_off; + for (i = 0; i < sr->sr_count; i++) { + struct ceph_sparse_extent *ext = &sr->sr_extent[i]; + u64 end; + + if (ext->off < pos) + return false; + if (check_add_overflow(ext->off, ext->len, &end)) + return false; + if (end > req_end) + return false; + pos = end; + } + + return true; +} + static int osd_sparse_read(struct ceph_connection *con, struct ceph_msg_data_cursor *cursor, char **pbuf) @@ -5852,6 +5878,10 @@ static int osd_sparse_read(struct ceph_connection *con, fallthrough; case CEPH_SPARSE_READ_DATA_LEN: convert_extent_map(sr); + if (!sparse_extent_map_valid(sr)) { + pr_warn_ratelimited("invalid sparse extent map\n"); + return -EREMOTEIO; + } ret = sizeof(sr->sr_datalen); *pbuf = (char *)&sr->sr_datalen; sr->sr_state = CEPH_SPARSE_READ_DATA_PRE;