From 870201f95fcbd19538aef630393fe9d583eff82e Mon Sep 17 00:00:00 2001 From: Maor Gottlieb Date: Wed, 16 Aug 2017 18:57:04 +0300 Subject: [PATCH] IB/uverbs: Fix NULL pointer dereference during device removal As part of ib_uverbs_remove_one which might be triggered upon reset flow, we trigger IB_EVENT_DEVICE_FATAL event to userspace application. If device was removed after uverbs fd was opened but before ib_uverbs_get_context was called, the event file will be accessed before it was allocated, result in NULL pointer dereference: [ 72.325873] BUG: unable to handle kernel NULL pointer dereference at (null) ... [ 72.325984] IP: _raw_spin_lock_irqsave+0x22/0x40 [ 72.327123] Call Trace: [ 72.327168] ib_uverbs_async_handler.isra.8+0x2e/0x160 [ib_uverbs] [ 72.327216] ? synchronize_srcu_expedited+0x27/0x30 [ 72.327269] ib_uverbs_remove_one+0x120/0x2c0 [ib_uverbs] [ 72.327330] ib_unregister_device+0xd0/0x180 [ib_core] [ 72.327373] mlx5_ib_remove+0x74/0x140 [mlx5_ib] [ 72.327422] mlx5_remove_device+0xfb/0x110 [mlx5_core] [ 72.327466] mlx5_unregister_interface+0x3c/0xa0 [mlx5_core] [ 72.327509] mlx5_ib_cleanup+0x10/0x962 [mlx5_ib] [ 72.327546] SyS_delete_module+0x155/0x230 [ 72.328472] ? exit_to_usermode_loop+0x70/0xa6 [ 72.329370] do_syscall_64+0x54/0xc0 [ 72.330262] entry_SYSCALL64_slow_path+0x25/0x25 Fix it by checking that user context was allocated before trigger the event. Fixes: 036b10635739 ('IB/uverbs: Enable device removal when there are active user space applications') Signed-off-by: Maor Gottlieb Reviewed-by: Matan Barak Signed-off-by: Leon Romanovsky Signed-off-by: Doug Ledford --- drivers/infiniband/core/uverbs_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c index c023e2c81b8f..5e530d2bee44 100644 --- a/drivers/infiniband/core/uverbs_main.c +++ b/drivers/infiniband/core/uverbs_main.c @@ -1153,7 +1153,6 @@ static void ib_uverbs_free_hw_resources(struct ib_uverbs_device *uverbs_dev, kref_get(&file->ref); mutex_unlock(&uverbs_dev->lists_mutex); - ib_uverbs_event_handler(&file->event_handler, &event); mutex_lock(&file->cleanup_mutex); ucontext = file->ucontext; @@ -1170,6 +1169,7 @@ static void ib_uverbs_free_hw_resources(struct ib_uverbs_device *uverbs_dev, * for example due to freeing the resources * (e.g mmput). */ + ib_uverbs_event_handler(&file->event_handler, &event); ib_dev->disassociate_ucontext(ucontext); mutex_lock(&file->cleanup_mutex); ib_uverbs_cleanup_ucontext(file, ucontext, true); -- 2.30.2