6.6-stable review patch. If anyone has any objections, please let me know.
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From: Yi Sun yi.sun@intel.com
[ Upstream commit f41c538881eec4dcf5961a242097d447f848cda6 ]
The call to idxd_free() introduces a duplicate put_device() leading to a reference count underflow: refcount_t: underflow; use-after-free. WARNING: CPU: 15 PID: 4428 at lib/refcount.c:28 refcount_warn_saturate+0xbe/0x110 ... Call Trace: <TASK> idxd_remove+0xe4/0x120 [idxd] pci_device_remove+0x3f/0xb0 device_release_driver_internal+0x197/0x200 driver_detach+0x48/0x90 bus_remove_driver+0x74/0xf0 pci_unregister_driver+0x2e/0xb0 idxd_exit_module+0x34/0x7a0 [idxd] __do_sys_delete_module.constprop.0+0x183/0x280 do_syscall_64+0x54/0xd70 entry_SYSCALL_64_after_hwframe+0x76/0x7e
The idxd_unregister_devices() which is invoked at the very beginning of idxd_remove(), already takes care of the necessary put_device() through the following call path: idxd_unregister_devices() -> device_unregister() -> put_device()
In addition, when CONFIG_DEBUG_KOBJECT_RELEASE is enabled, put_device() may trigger asynchronous cleanup via schedule_delayed_work(). If idxd_free() is called immediately after, it can result in a use-after-free.
Remove the improper idxd_free() to avoid both the refcount underflow and potential memory corruption during module unload.
Fixes: d5449ff1b04d ("dmaengine: idxd: Add missing idxd cleanup to fix memory leak in remove call") Signed-off-by: Yi Sun yi.sun@intel.com Tested-by: Shuai Xue xueshuai@linux.alibaba.com Reviewed-by: Dave Jiang dave.jiang@intel.com Acked-by: Vinicius Costa Gomes vinicius.gomes@intel.com
Link: https://lore.kernel.org/r/20250729150313.1934101-2-yi.sun@intel.com Signed-off-by: Vinod Koul vkoul@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/dma/idxd/init.c | 1 - 1 file changed, 1 deletion(-)
diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c index 92e86ae9db29d..3a78973882211 100644 --- a/drivers/dma/idxd/init.c +++ b/drivers/dma/idxd/init.c @@ -907,7 +907,6 @@ static void idxd_remove(struct pci_dev *pdev) idxd_cleanup(idxd); pci_iounmap(pdev, idxd->reg_base); put_device(idxd_confdev(idxd)); - idxd_free(idxd); pci_disable_device(pdev); }