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cxl/region: Guard against a missing peer mapping

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When two endpoints share a dport, both must be mapped by the port.

sashiko-bot reports that a missing peer mapping could result in a NULL
pointer dereference during region creation.

No caller can reach this today. Guard it anyway so a future violation
of the mapping requirement fails region creation rather than causing
an oops.

Reported-by: sashiko-bot@kernel.org
Link: https://sashiko.dev/#/patchset/cover.1787255388.git.alison.schofield%40intel.com?part=3
Assisted-by: Claude:claude-opus-5
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Richard Cheng <icheng@nvidia.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://patch.msgid.link/20260821222515.2675707-1-alison.schofield@intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
This commit is contained in:
Alison Schofield 2026-08-21 15:25:14 -07:00 committed by Dave Jiang
parent cee9395acd
commit b212e37113
1 changed files with 3 additions and 2 deletions
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5
drivers/cxl/core/region.c
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@ -1367,7 +1367,8 @@ static int check_last_peer(struct cxl_endpoint_decoder *cxled,
/*
* If this position wants to share a dport with the last endpoint mapped
* then that endpoint, at index 'position - distance', must also be
* mapped by this dport.
* mapped by this dport. An endpoint that this port does not map at all
* fails that requirement.
*/
if (pos < distance) {
dev_dbg(&cxlr->dev, "%s:%s: cannot host %s:%s at %d\n",
@ -1378,7 +1379,7 @@ static int check_last_peer(struct cxl_endpoint_decoder *cxled,
cxled_peer = p->targets[pos - distance];
cxlmd_peer = cxled_to_memdev(cxled_peer);
ep_peer = cxl_ep_load(port, cxlmd_peer);
if (ep->dport != ep_peer->dport) {
if (!ep_peer || ep->dport != ep_peer->dport) {
dev_dbg(&cxlr->dev,
"%s:%s: %s:%s pos %d mismatched peer %s:%s\n",
dev_name(port->uport_dev), dev_name(&port->dev),