7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Nirmoy Das commit 440ca8a4b69f40088065b9e05ef11373292a254e upstream. iommufd_eventq_fops_release() drops the file's users reference before reading eventq->ictx. Once that reference is dropped, IOMMU_DESTROY in another thread can remove and free the event queue, so the later load accesses freed memory. Read ictx while the users reference still pins the event queue, then drop the reference and put the saved context. The context reference taken by iommufd_eventq_init() keeps ictx valid until the put. Fault and vEVENTQ file descriptors share this release path. Fixes: 07838f7fd529 ("iommufd: Add iommufd fault object") Cc: stable@vger.kernel.org Assisted-by: LLM, Specula Signed-off-by: Nirmoy Das Link: https://patch.msgid.link/20261014133632.3440297-1-nirmoyd@nvidia.com Signed-off-by: Jason Gunthorpe Signed-off-by: Greg Kroah-Hartman --- drivers/iommu/iommufd/eventq.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/drivers/iommu/iommufd/eventq.c +++ b/drivers/iommu/iommufd/eventq.c @@ -396,9 +396,11 @@ static __poll_t iommufd_eventq_fops_poll static int iommufd_eventq_fops_release(struct inode *inode, struct file *filep) { struct iommufd_eventq *eventq = filep->private_data; + /* eventq may be freed once the users reference is dropped. */ + struct iommufd_ctx *ictx = eventq->ictx; refcount_dec(&eventq->obj.users); - iommufd_ctx_put(eventq->ictx); + iommufd_ctx_put(ictx); return 0; }