Revision a7d8d1c7a7f73e780aa9ae74926ae5985b2f895f authored by Andrew Lunn on 14 June 2021, 15:55:23 UTC, committed by Greg Kroah-Hartman on 17 June 2021, 13:34:21 UTC
The Cypress CY7C65632 appears to have an issue with auto suspend and detecting devices, not too dissimilar to the SMSC 5534B hub. It is easiest to reproduce by connecting multiple mass storage devices to the hub at the same time. On a Lenovo Yoga, around 1 in 3 attempts result in the devices not being detected. It is however possible to make them appear using lsusb -v. Disabling autosuspend for this hub resolves the issue. Fixes: 1208f9e1d758 ("USB: hub: Fix the broken detection of USB3 device in SMSC hub") Cc: stable@vger.kernel.org Signed-off-by: Andrew Lunn <andrew@lunn.ch> Link: https://lore.kernel.org/r/20210614155524.2228800-1-andrew@lunn.ch Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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stackleak.c
// SPDX-License-Identifier: GPL-2.0
/*
* This code fills the used part of the kernel stack with a poison value
* before returning to userspace. It's part of the STACKLEAK feature
* ported from grsecurity/PaX.
*
* Author: Alexander Popov <alex.popov@linux.com>
*
* STACKLEAK reduces the information which kernel stack leak bugs can
* reveal and blocks some uninitialized stack variable attacks.
*/
#include <linux/stackleak.h>
#include <linux/kprobes.h>
#ifdef CONFIG_STACKLEAK_RUNTIME_DISABLE
#include <linux/jump_label.h>
#include <linux/sysctl.h>
static DEFINE_STATIC_KEY_FALSE(stack_erasing_bypass);
int stack_erasing_sysctl(struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
int ret = 0;
int state = !static_branch_unlikely(&stack_erasing_bypass);
int prev_state = state;
table->data = &state;
table->maxlen = sizeof(int);
ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
state = !!state;
if (ret || !write || state == prev_state)
return ret;
if (state)
static_branch_disable(&stack_erasing_bypass);
else
static_branch_enable(&stack_erasing_bypass);
pr_warn("stackleak: kernel stack erasing is %s\n",
state ? "enabled" : "disabled");
return ret;
}
#define skip_erasing() static_branch_unlikely(&stack_erasing_bypass)
#else
#define skip_erasing() false
#endif /* CONFIG_STACKLEAK_RUNTIME_DISABLE */
asmlinkage void notrace stackleak_erase(void)
{
/* It would be nice not to have 'kstack_ptr' and 'boundary' on stack */
unsigned long kstack_ptr = current->lowest_stack;
unsigned long boundary = (unsigned long)end_of_stack(current);
unsigned int poison_count = 0;
const unsigned int depth = STACKLEAK_SEARCH_DEPTH / sizeof(unsigned long);
if (skip_erasing())
return;
/* Check that 'lowest_stack' value is sane */
if (unlikely(kstack_ptr - boundary >= THREAD_SIZE))
kstack_ptr = boundary;
/* Search for the poison value in the kernel stack */
while (kstack_ptr > boundary && poison_count <= depth) {
if (*(unsigned long *)kstack_ptr == STACKLEAK_POISON)
poison_count++;
else
poison_count = 0;
kstack_ptr -= sizeof(unsigned long);
}
/*
* One 'long int' at the bottom of the thread stack is reserved and
* should not be poisoned (see CONFIG_SCHED_STACK_END_CHECK=y).
*/
if (kstack_ptr == boundary)
kstack_ptr += sizeof(unsigned long);
#ifdef CONFIG_STACKLEAK_METRICS
current->prev_lowest_stack = kstack_ptr;
#endif
/*
* Now write the poison value to the kernel stack. Start from
* 'kstack_ptr' and move up till the new 'boundary'. We assume that
* the stack pointer doesn't change when we write poison.
*/
if (on_thread_stack())
boundary = current_stack_pointer;
else
boundary = current_top_of_stack();
while (kstack_ptr < boundary) {
*(unsigned long *)kstack_ptr = STACKLEAK_POISON;
kstack_ptr += sizeof(unsigned long);
}
/* Reset the 'lowest_stack' value for the next syscall */
current->lowest_stack = current_top_of_stack() - THREAD_SIZE/64;
}
NOKPROBE_SYMBOL(stackleak_erase);
void __used __no_caller_saved_registers notrace stackleak_track_stack(void)
{
unsigned long sp = current_stack_pointer;
/*
* Having CONFIG_STACKLEAK_TRACK_MIN_SIZE larger than
* STACKLEAK_SEARCH_DEPTH makes the poison search in
* stackleak_erase() unreliable. Let's prevent that.
*/
BUILD_BUG_ON(CONFIG_STACKLEAK_TRACK_MIN_SIZE > STACKLEAK_SEARCH_DEPTH);
/* 'lowest_stack' should be aligned on the register width boundary */
sp = ALIGN(sp, sizeof(unsigned long));
if (sp < current->lowest_stack &&
sp >= (unsigned long)task_stack_page(current) +
sizeof(unsigned long)) {
current->lowest_stack = sp;
}
}
EXPORT_SYMBOL(stackleak_track_stack);
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