From 1039bffd6ae9c75b42b7d148d6c1106134107b66 Mon Sep 17 00:00:00 2001 From: Xie Yuanbin Date: Tue, 28 Jul 2026 03:16:42 +0100 Subject: ARM: 9485/1: mm: acquire mmap write lock around show_pte() for user faults When CONFIG_DEBUG_USER=y, and cmdline "user_debug=31" is set, a user fault may trigger show_pte() without any lock. If another thread in the same process concurrently calls munmap(), the page table pages may be freed while show_pte() is still traversing them, causing a use-after-free in show_pte(). If CONFIG_ARM_LPAE=y, this may cause a kernel panic if the pages table of PMD are freed when show_pte() is running. Acquire mmap_write_lock() around show_pte() for user faults to fix the contention. For user faults, additionally restrict that show_pte() is called only when the addr is a user-space address (addr < TASK_SIZE). This is because the lock of tsk->mm only protects the virtual memory of user address space, furthermore, dumping the page tables of a kernel-space address for user faults is unnecessary and may have security implications. Keep everything unchanged for kernel faults, because the kernel is already in the "oops" state, acquiring a lock may risk a deadlock. Co-developed-by: Qi Xi Fixes: 6d021b724481 ("ARM: dump pgd, pmd and pte states on unhandled data abort faults") Link: https://lore.kernel.org/20260716014022.2823-1-xieyuanbin1@huawei.com Acked-by: Lorenzo Stoakes (ARM) Reviewed-by: Linus Walleij Signed-off-by: Qi Xi Signed-off-by: Xie Yuanbin Signed-off-by: Russell King --- drivers/net/netdevsim/tc.c | 97 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 97 insertions(+) create mode 100644 drivers/net/netdevsim/tc.c (limited to 'drivers/net/netdevsim/tc.c') diff --git a/drivers/net/netdevsim/tc.c b/drivers/net/netdevsim/tc.c new file mode 100644 index 000000000..a415e02a6 --- /dev/null +++ b/drivers/net/netdevsim/tc.c @@ -0,0 +1,97 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include + +#include "netdevsim.h" + +static int +nsim_setup_tc_block_cb(enum tc_setup_type type, void *type_data, void *cb_priv) +{ + struct flow_cls_common_offload *common = type_data; + int err = 0; + + switch (type) { + case TC_SETUP_CLSBPF: + err = nsim_bpf_setup_tc_block_cb(type, type_data, cb_priv); + break; + case TC_SETUP_CLSFLOWER: + break; + default: + NSIM_EA(common->extack, "offload type not supported"); + err = -EOPNOTSUPP; + break; + } + + return err; +} + +static void nsim_taprio_stats(struct tc_taprio_qopt_stats *stats) +{ + stats->window_drops = 0; + stats->tx_overruns = 0; +} + +static int nsim_setup_tc_taprio(struct net_device *dev, + struct tc_taprio_qopt_offload *offload) +{ + int err = 0; + + switch (offload->cmd) { + case TAPRIO_CMD_REPLACE: + case TAPRIO_CMD_DESTROY: + break; + case TAPRIO_CMD_STATS: + nsim_taprio_stats(&offload->stats); + break; + default: + err = -EOPNOTSUPP; + } + + return err; +} + +static int nsim_setup_tc_ets(struct net_device *dev, + struct tc_ets_qopt_offload *offload) +{ + int err = 0; + + switch (offload->command) { + case TC_ETS_REPLACE: + case TC_ETS_DESTROY: + break; + case TC_ETS_STATS: + _bstats_update(offload->stats.bstats, 0, 0); + break; + default: + err = -EOPNOTSUPP; + } + + return err; +} + +static LIST_HEAD(nsim_block_cb_list); + +int +nsim_setup_tc(struct net_device *dev, enum tc_setup_type type, void *type_data) +{ + struct netdevsim *ns = netdev_priv(dev); + + switch (type) { + case TC_SETUP_QDISC_TAPRIO: + return nsim_setup_tc_taprio(dev, type_data); + case TC_SETUP_QDISC_ETS: + return nsim_setup_tc_ets(dev, type_data); + case TC_SETUP_BLOCK: + return flow_block_cb_setup_simple(type_data, + &nsim_block_cb_list, + nsim_setup_tc_block_cb, + ns, ns, true); + case TC_SETUP_FT: + return 0; + default: + return -EOPNOTSUPP; + } +} +ALLOW_ERROR_INJECTION(nsim_setup_tc, ERRNO); -- cgit v1.3.1