This is a note to let you know that I've just added the patch titled
usb: usbfs: Use consistent mmap functions
to the 6.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
usb-usbfs-use-consistent-mmap-functions.patch
and it can be found in the queue-6.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d0b861653f8c16839c3035875b556afc4472f941 Mon Sep 17 00:00:00 2001
From: Ruihan Li <lrh2000@xxxxxxxxxx>
Date: Mon, 15 May 2023 21:09:56 +0800
Subject: usb: usbfs: Use consistent mmap functions
From: Ruihan Li <lrh2000@xxxxxxxxxx>
commit d0b861653f8c16839c3035875b556afc4472f941 upstream.
When hcd->localmem_pool is non-null, localmem_pool is used to allocate
DMA memory. In this case, the dma address will be properly returned (in
dma_handle), and dma_mmap_coherent should be used to map this memory
into the user space. However, the current implementation uses
pfn_remap_range, which is supposed to map normal pages.
Instead of repeating the logic in the memory allocation function, this
patch introduces a more robust solution. Here, the type of allocated
memory is checked by testing whether dma_handle is properly set. If
dma_handle is properly returned, it means some DMA pages are allocated
and dma_mmap_coherent should be used to map them. Otherwise, normal
pages are allocated and pfn_remap_range should be called. This ensures
that the correct mmap functions are used consistently, independently
with logic details that determine which type of memory gets allocated.
Fixes: a0e710a7def4 ("USB: usbfs: fix mmap dma mismatch")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Ruihan Li <lrh2000@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230515130958.32471-3-lrh2000@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/core/devio.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -235,7 +235,7 @@ static int usbdev_mmap(struct file *file
size_t size = vma->vm_end - vma->vm_start;
void *mem;
unsigned long flags;
- dma_addr_t dma_handle;
+ dma_addr_t dma_handle = DMA_MAPPING_ERROR;
int ret;
ret = usbfs_increase_memory_usage(size + sizeof(struct usb_memory));
@@ -265,7 +265,14 @@ static int usbdev_mmap(struct file *file
usbm->vma_use_count = 1;
INIT_LIST_HEAD(&usbm->memlist);
- if (hcd->localmem_pool || !hcd_uses_dma(hcd)) {
+ /*
+ * In DMA-unavailable cases, hcd_buffer_alloc_pages allocates
+ * normal pages and assigns DMA_MAPPING_ERROR to dma_handle. Check
+ * whether we are in such cases, and then use remap_pfn_range (or
+ * dma_mmap_coherent) to map normal (or DMA) pages into the user
+ * space, respectively.
+ */
+ if (dma_handle == DMA_MAPPING_ERROR) {
if (remap_pfn_range(vma, vma->vm_start,
virt_to_phys(usbm->mem) >> PAGE_SHIFT,
size, vma->vm_page_prot) < 0) {
Patches currently in stable-queue which might be from lrh2000@xxxxxxxxxx are
queue-6.3/usb-usbfs-enforce-page-requirements-for-mmap.patch
queue-6.3/mm-page_table_check-make-it-dependent-on-exclusive_system_ram.patch
queue-6.3/usb-usbfs-use-consistent-mmap-functions.patch
queue-6.3/mm-page_table_check-ensure-user-pages-are-not-slab-pages.patch
