Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: iio: buffer: Fix DMA fence leak in iio_buffer_enqueue_dmabuf() iio_buffer_enqueue_dmabuf() allocates a struct iio_dma_fence (104 bytes, kmalloc-128) via kmalloc_obj()+dma_fence_init(), which sets the initial kref to 1. It then calls dma_resv_add_fence() which takes a second reference (kref=2), and stores a raw pointer in block->fence. On the success path the function returns without calling dma_fence_put() to release the initial reference, so every buffer enqueue permanently leaks one kmalloc-128 allocation. The iio_buffer_cleanup() work item only releases the temporary reference taken during completion signalling by iio_buffer_signal_dmabuf_done(); the initial reference from dma_fence_init() is never released. With four iio_rwdev instances at 240kHz and 512 samples per buffer, this produces ~1875 kmalloc-128 allocations per second matching the observed slab growth exactly. A test with ftrace confirmed that the dma_fence_destroy event was never triggered. Fix by calling dma_fence_put() after dma_resv_add_fence(), transferring ownership of the fence to the DMA reservation object. The DMA fence then gets properly discarded after being signalled.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 3e26d9f08fbe0b73e951a5e810fdb7a332b7e37f before 9678aeed8b77d495a417dd057d479f3733094019; affected 3e26d9f08fbe0b73e951a5e810fdb7a332b7e37f before 3412a95afaa5d3262008dfc34f3c7be33d8151dc; affected 3e26d9f08fbe0b73e951a5e810fdb7a332b7e37f before 96cdeaba6a008503455b78a9641c05c2a886a7ec; affected 3e26d9f08fbe0b73e951a5e810fdb7a332b7e37f before a093999355084bdbfe6e97f1dd232e58a1525f0b |
| Linux / Linux | affected 6.11; unaffected 0 before 6.11; unaffected 6.12.93 through 6.12.*; unaffected 6.18.35 through 6.18.*; unaffected 7.0.12 through 7.0.*; unaffected 7.1 through * |
CWE
No CWE identifiers supplied.