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charset=us-ascii Content-Disposition: inline In-Reply-To: <20260905102901.126035-2-changhuang.liang@starfivetech.com> X-Debian-User: leitao On Sat, Sep 05, 2026 at 03:28:58AM -0700, Changhuang Liang wrote: > +ssize_t uart_routing_show(struct device *dev, struct device_attribute *attr, > + char *buf) > +{ > + const struct uart_routing_selector *sel = to_uart_routing_selector(attr); > + struct uart_routing *routing = uart_routing_from_dev(dev); > + unsigned int val, pos; > + int len, ret; > + > + ret = regmap_read(routing->regmap, sel->reg, &val); It seems routing can be NULL here if the file is read while the device is being unbound, and uart_routing_store() has the same problem. I hit this while testing v2 on arm64 (next-20261008 with KASAN), and the code is unchanged in v3. d=/sys/bus/platform/devices/$DEV drv=/sys/bus/platform/drivers/aspeed-uart-routing while :; do cat $d/uart1; done >/dev/null 2>&1 & while :; do echo $DEV > $drv/unbind; echo $DEV > $drv/bind; done and then got: KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] Internal error: Oops: 0000000096000006 [#1] SMP pc : uart_routing_show+0x64/0x288 [uart_routing] Call trace: uart_routing_show+0x64/0x288 [uart_routing] (P) dev_attr_show+0x64/0xc0 sysfs_kf_seq_show+0x21c/0x380 kernfs_seq_show+0x138/0x1c8 seq_read_iter+0x358/0xa30 kernfs_fop_read_iter+0x438/0x500 vfs_read+0x484/0x6f0 --breno