[PATCH 6.18 040/396] mshv: Fix duplicate GSI detection for GSI 0
Greg Kroah-Hartman <[email protected]>
| Newsgroups | org.kernel.vger.stable,dev.linux.lists.patches |
|---|---|
| Message-ID | <[email protected]> |
6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Stanislav Kinsburskii <[email protected]> [ Upstream commit 649dd135491945afa544351e3e6d4a727de87020 ] The duplicate routing entry check in mshv_update_routing_table() uses guest_irq_num != 0 to detect whether a GSI slot is already occupied. This fails for GSI 0 because its guest_irq_num is 0 both when the slot is unused (zero-initialized) and when legitimately assigned. As a result, duplicate entries for GSI 0 are silently accepted, with the second entry overwriting the first — corrupting the routing table without any error reported to userspace. While GSI 0 (legacy timer) is unlikely to appear in MSI-based routing in practice, the check is semantically wrong — it conflates "uninitialized" with "GSI number 0." Use girq_entry_valid instead, which is explicitly set to true when an entry is populated and remains zero for unused slots regardless of the GSI number. Fixes: 621191d709b14 ("Drivers: hv: Introduce mshv_root module to expose /dev/mshv to VMMs") Signed-off-by: Stanislav Kinsburskii <[email protected]> Reviewed-by: Anirudh Rayabharam (Microsoft) <[email protected]> Signed-off-by: Wei Liu <[email protected]> Signed-off-by: Sasha Levin <[email protected]> --- drivers/hv/mshv_irq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/hv/mshv_irq.c b/drivers/hv/mshv_irq.c index d0fb9ef734f42..743777b4886d3 100644 --- a/drivers/hv/mshv_irq.c +++ b/drivers/hv/mshv_irq.c @@ -51,7 +51,7 @@ int mshv_update_routing_table(struct mshv_partition *partition, /* * Allow only one to one mapping between GSI and MSI routing. */ - if (girq->guest_irq_num != 0) { + if (girq->girq_entry_valid) { r = -EINVAL; goto out; } -- 2.53.0