6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Adrian Hunter [ Upstream commit b1a25e8e143ef880450e6399fb0733b66a1c29f0 ] The controller writes whole DWORDs, so a read whose length is not a multiple of 4 overwrites up to 3 bytes past the end of the destination buffer. That is a property of the controller, not of the IOMMU, but the bounce buffer that works around it was used only when the device was IOMMU mapped. Everywhere else the buffer is left unprotected. Drop the device_iommu_mapped() condition. The overrun is easily seen with CONFIG_SLUB_DEBUG=y and kernel command line options intel_iommu=off slub_debug=FZPU, which reports it as a kmalloc redzone overwrite, like: [kmalloc Redzone overwritten] 0xffff8a354561570e-0xffff8a354561570f @offset=1806. First byte 0x15 instead of 0xcc ============================================================================= BUG kmalloc-8 (Not tainted): Object corrupt Allocated in i3c_master_retrieve_dev_info+0xc1/0x760 age=40 cpu=6 pid=1 ... Freed in i3c_master_enec_disec_locked+0xeb/0x140 age=40 cpu=6 pid=1 ... WARNING: mm/slub.c:1233 at object_err+0x1c1/0x1cf, CPU#6: swapper/0/1 ... Fixes: 9e23897bca62 ("i3c: mipi-i3c-hci: Use physical device pointer with DMA API") Cc: stable@vger.kernel.org Signed-off-by: Adrian Hunter Reviewed-by: Frank Li Link: https://patch.msgid.link/20260920151248.46936-3-adrian.hunter@intel.com Signed-off-by: Alexandre Belloni Signed-off-by: Sasha Levin --- drivers/i3c/master/mipi-i3c-hci/dma.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/i3c/master/mipi-i3c-hci/dma.c b/drivers/i3c/master/mipi-i3c-hci/dma.c index 37717e530a250..15a34429197b5 100644 --- a/drivers/i3c/master/mipi-i3c-hci/dma.c +++ b/drivers/i3c/master/mipi-i3c-hci/dma.c @@ -376,7 +376,7 @@ static void hci_dma_unmap_xfer(struct i3c_hci *hci, static struct i3c_dma *hci_dma_map_xfer(struct device *dev, struct hci_xfer *xfer) { enum dma_data_direction dir = xfer->rnw ? DMA_FROM_DEVICE : DMA_TO_DEVICE; - bool need_bounce = device_iommu_mapped(dev) && xfer->rnw && (xfer->data_len & 3); + bool need_bounce = xfer->rnw && (xfer->data_len & 3); return i3c_master_dma_map_single(dev, xfer->data, xfer->data_len, need_bounce, dir); } -- 2.53.0