7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: James Kim commit 0f2cd84858e67cf8e02438bf28243bcdc67aa49a upstream. A use-after-free vulnerability was identified in mport_mm_close() in drivers/rapidio/devices/rio_mport_cdev.c, identical to the pattern previously addressed in dma_req_free(). This is observable from userspace when an application creates an mmap mapping via the RapidIO character device and subsequently unmaps it (or terminates, triggering exit_mmap()). During munmap, mport_mm_close() is invoked and drops the mapping reference via kref_put(). If kref_put() drops the last reference, mport_release_mapping() is called, which frees the underlying rio_mport_mapping structure. The subsequent mutex_unlock() then dereferences map->md to unlock buf_mutex, leading to a use-after-free: mport_mm_close() -> mutex_lock(&map->md->buf_mutex); ... -> kref_put(&map->ref, mport_release_mapping); /* map is freed */ -> mutex_unlock(&map->md->buf_mutex); /* UAF: map used */ Fix this by caching map->md before kref_put() and using the cached pointer for mutex unlocking, ensuring that freed memory is not accessed. Link: https://lore.kernel.org/20260914042327.49798-1-james010kim@gmail.com Fixes: e8de370188d0 ("rapidio: add mport char device driver") Signed-off-by: James Kim Signed-off-by: Andrew Morton Cc: Alexandre Bounine Cc: Dan Carpenter Cc: Greg Kroah-Hartman Cc: Matt Porter Cc: Signed-off-by: Greg Kroah-Hartman --- drivers/rapidio/devices/rio_mport_cdev.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/drivers/rapidio/devices/rio_mport_cdev.c +++ b/drivers/rapidio/devices/rio_mport_cdev.c @@ -2167,11 +2167,12 @@ static void mport_mm_open(struct vm_area static void mport_mm_close(struct vm_area_struct *vma) { struct rio_mport_mapping *map = vma->vm_private_data; + struct mport_dev *md = map->md; rmcd_debug(MMAP, "%pad", &map->phys_addr); - mutex_lock(&map->md->buf_mutex); + mutex_lock(&md->buf_mutex); kref_put(&map->ref, mport_release_mapping); - mutex_unlock(&map->md->buf_mutex); + mutex_unlock(&md->buf_mutex); } static const struct vm_operations_struct vm_ops = {