diff options
| author | Paul Cercueil <paul@crapouillou.net> | 2026-06-09 17:29:05 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-06-25 15:11:56 +0100 |
| commit | baa6b6068a3f2bf2ed525a1cb37975905dadc658 (patch) | |
| tree | 29175d65492c6962e5b5fbf4090fbec8930b96b7 | |
| parent | d092d7edf8faefa3e27b9fc7f0e7904b06c833a2 (diff) | |
| download | linux-next-baa6b6068a3f2bf2ed525a1cb37975905dadc658.tar.gz linux-next-baa6b6068a3f2bf2ed525a1cb37975905dadc658.zip | |
usb: gadget: f_fs: Fix DMA fence leak
In ffs_dmabuf_transfer(), a ffs_dma_fence object is kmalloc'd, with the
underlying dma_fence later initialized by dma_fence_init(), which sets
its kref counter to 1. Then, dma_resv_add_fence() gets a second
reference, and a pointer to the ffs_dma_fence is passed as the
usb_request's "context" field.
The dma-resv mechanism will manage the second reference, but the first
reference is never properly released; the ffs_dmabuf_cleanup() function
decreases the reference count, but only to balance with the reference
grab in ffs_dmabuf_signal_done().
The code will then slowly leak memory as more ffs_dma_fence objects are
created without being ever freed.
Address this issue by transferring ownership of the fence to the DMA
reservation object, by calling dma_fence_put() right after
dma_resv_add_fence(). The ffs_dma_fence then gets properly discarded
after being signalled.
Fixes: 7b07a2a7ca02 ("usb: gadget: functionfs: Add DMABUF import interface")
Cc: stable <stable@kernel.org>
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Tested-by: Nuno Sá <nuno.sa@analog.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Link: https://patch.msgid.link/20260609152905.729328-1-paul@crapouillou.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/gadget/function/f_fs.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c index 75912ce6ab55..7cc446502980 100644 --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -1704,6 +1704,7 @@ static int ffs_dmabuf_transfer(struct file *file, resv_dir = epfile->in ? DMA_RESV_USAGE_READ : DMA_RESV_USAGE_WRITE; dma_resv_add_fence(dmabuf->resv, &fence->base, resv_dir); + dma_fence_put(&fence->base); dma_resv_unlock(dmabuf->resv); /* Now that the dma_fence is in place, queue the transfer. */ |