From: Lizhi Hou <lizhi.hou@amd.com>
Date: Mon, 6 Jul 2026 22:12:28 +0000 (-0700)
Subject: accel/amdxdna: Fix potential amdxdna_umap lifetime race
X-Git-Tag: v7.2-rc3~27^2~3^2~11
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=14f172eff9c19f8043a9858845f33cd034f3a41e;p=thirdparty%2Fkernel%2Flinux.git

accel/amdxdna: Fix potential amdxdna_umap lifetime race

amdxdna_umap_release() calls the blocking mmu_interval_notifier_remove()
before removing the object from abo->mem.umap_list. If
aie2_populate_range() runs concurrently, it may obtain a reference to an
amdxdna_umap that is being released, leading to a potential use-after-free.

Use kref_get_unless_zero() in aie2_populate_range() when acquiring a
reference. If the reference count has already dropped to zero, release
is in progress and the entry is skipped.

Fixes: e486147c912f ("accel/amdxdna: Add BO import and export")
Reviewed-by: Max Zhen <max.zhen@amd.com>
Signed-off-by: Lizhi Hou <lizhi.hou@amd.com>
Link: https://patch.msgid.link/20260706221228.434099-1-lizhi.hou@amd.com
---

diff --git a/drivers/accel/amdxdna/aie2_ctx.c b/drivers/accel/amdxdna/aie2_ctx.c
index 408ff7e2a272..7bf635634e64 100644
--- a/drivers/accel/amdxdna/aie2_ctx.c
+++ b/drivers/accel/amdxdna/aie2_ctx.c
@@ -1039,7 +1039,7 @@ again:
 	found = false;
 	down_write(&xdna->notifier_lock);
 	list_for_each_entry(mapp, &abo->mem.umap_list, node) {
-		if (mapp->invalid) {
+		if (mapp->invalid && kref_get_unless_zero(&mapp->refcnt)) {
 			found = true;
 			break;
 		}
@@ -1050,7 +1050,7 @@ again:
 		up_write(&xdna->notifier_lock);
 		return 0;
 	}
-	kref_get(&mapp->refcnt);
+
 	up_write(&xdna->notifier_lock);
 
 	mm = mapp->notifier.mm;