From 4310c6b8e75d6a47f7548e5948fbe6318aa4440a Mon Sep 17 00:00:00 2001 From: Fedor Pchelkin Date: Mon, 31 Aug 2026 10:58:09 +0300 Subject: thunderbolt: Fix NULL dereference in tb_remove_work() There is a slight race between tb_remove_work() and tb_domain_remove() which leads to dereferencing a NULL tb->root_switch pointer inside tb_free_unplugged_xdomains(): Thread A Thread B tb_remove_work() tb_domain_remove() mutex_lock(&tb->lock) tb_stop() /* doesn't cancel a running callback */ cancel_delayed_work(&tcm->remove_work) ... tb_switch_remove(tb->root_switch) tb->root_switch = NULL mutex_unlock(&tb->lock) mutex_lock(&tb->lock) ... /* without checking ->root_switch */ tb_free_unplugged_xdomains(tb->root_switch) mutex_unlock(&tb->lock) Commit a8937f35cf39 ("thunderbolt: Remove XDomain from the bus without holding tb->lock") doesn't seem right to move tb_free_unplugged_xdomains() out of the &tb->lock section and the check for tb->root_switch, in particular. It states: For this reason separate removing the XDomain from the topology data structures (where we need the lock) from unregistering the device from the bus (where remove callbacks of the drivers are being called). tb_free_unplugged_xdomains() belongs to the former group of functions requiring the lock. And it also calls tb_xdomain_remove() which should only be called with &tb->lock held. Found by Linux Verification Center (linuxtesting.org) with Svace static analysis tool. Fixes: a8937f35cf39 ("thunderbolt: Remove XDomain from the bus without holding tb->lock") Cc: stable@vger.kernel.org Signed-off-by: Fedor Pchelkin Signed-off-by: Mika Westerberg --- drivers/gpu/trace/Kconfig | 13 +++++++++++++ drivers/gpu/trace/Makefile | 3 +++ drivers/gpu/trace/trace_gpu_mem.c | 13 +++++++++++++ 3 files changed, 29 insertions(+) create mode 100644 drivers/gpu/trace/Kconfig create mode 100644 drivers/gpu/trace/Makefile create mode 100644 drivers/gpu/trace/trace_gpu_mem.c (limited to 'drivers/gpu/trace') diff --git a/drivers/gpu/trace/Kconfig b/drivers/gpu/trace/Kconfig new file mode 100644 index 000000000..cd3d19c4a --- /dev/null +++ b/drivers/gpu/trace/Kconfig @@ -0,0 +1,13 @@ +# SPDX-License-Identifier: GPL-2.0-only + +config TRACE_GPU_MEM + bool "Enable GPU memory usage tracepoints" + default n + help + Choose this option to enable tracepoints for tracking + global and per-process GPU memory usage. Intended for + performance profiling and required for Android. + + Tracepoint availability varies by GPU driver. + + If in doubt, say "N". diff --git a/drivers/gpu/trace/Makefile b/drivers/gpu/trace/Makefile new file mode 100644 index 000000000..b70fbdc58 --- /dev/null +++ b/drivers/gpu/trace/Makefile @@ -0,0 +1,3 @@ +# SPDX-License-Identifier: GPL-2.0 + +obj-$(CONFIG_TRACE_GPU_MEM) += trace_gpu_mem.o diff --git a/drivers/gpu/trace/trace_gpu_mem.c b/drivers/gpu/trace/trace_gpu_mem.c new file mode 100644 index 000000000..01e855897 --- /dev/null +++ b/drivers/gpu/trace/trace_gpu_mem.c @@ -0,0 +1,13 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * GPU memory trace points + * + * Copyright (C) 2020 Google, Inc. + */ + +#include + +#define CREATE_TRACE_POINTS +#include + +EXPORT_TRACEPOINT_SYMBOL(gpu_mem_total); -- cgit v1.3.1