Revision 513dc792d6060d5ef572e43852683097a8420f56 authored by Zhang Xiaoxu on 04 March 2020, 02:24:29 UTC, committed by Daniel Vetter on 06 March 2020, 20:06:34 UTC
When syzkaller tests, there is a UAF: BUG: KASan: use after free in vgacon_invert_region+0x9d/0x110 at addr ffff880000100000 Read of size 2 by task syz-executor.1/16489 page:ffffea0000004000 count:0 mapcount:-127 mapping: (null) index:0x0 page flags: 0xfffff00000000() page dumped because: kasan: bad access detected CPU: 1 PID: 16489 Comm: syz-executor.1 Not tainted Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014 Call Trace: [<ffffffffb119f309>] dump_stack+0x1e/0x20 [<ffffffffb04af957>] kasan_report+0x577/0x950 [<ffffffffb04ae652>] __asan_load2+0x62/0x80 [<ffffffffb090f26d>] vgacon_invert_region+0x9d/0x110 [<ffffffffb0a39d95>] invert_screen+0xe5/0x470 [<ffffffffb0a21dcb>] set_selection+0x44b/0x12f0 [<ffffffffb0a3bfae>] tioclinux+0xee/0x490 [<ffffffffb0a1d114>] vt_ioctl+0xff4/0x2670 [<ffffffffb0a0089a>] tty_ioctl+0x46a/0x1a10 [<ffffffffb052db3d>] do_vfs_ioctl+0x5bd/0xc40 [<ffffffffb052e2f2>] SyS_ioctl+0x132/0x170 [<ffffffffb11c9b1b>] system_call_fastpath+0x22/0x27 Memory state around the buggy address: ffff8800000fff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8800000fff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff880000100000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff It can be reproduce in the linux mainline by the program: #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <fcntl.h> #include <sys/types.h> #include <sys/stat.h> #include <sys/ioctl.h> #include <linux/vt.h> struct tiocl_selection { unsigned short xs; /* X start */ unsigned short ys; /* Y start */ unsigned short xe; /* X end */ unsigned short ye; /* Y end */ unsigned short sel_mode; /* selection mode */ }; #define TIOCL_SETSEL 2 struct tiocl { unsigned char type; unsigned char pad; struct tiocl_selection sel; }; int main() { int fd = 0; const char *dev = "/dev/char/4:1"; struct vt_consize v = {0}; struct tiocl tioc = {0}; fd = open(dev, O_RDWR, 0); v.v_rows = 3346; ioctl(fd, VT_RESIZEX, &v); tioc.type = TIOCL_SETSEL; ioctl(fd, TIOCLINUX, &tioc); return 0; } When resize the screen, update the 'vc->vc_size_row' to the new_row_size, but when 'set_origin' in 'vgacon_set_origin', vgacon use 'vga_vram_base' for 'vc_origin' and 'vc_visible_origin', not 'vc_screenbuf'. It maybe smaller than 'vc_screenbuf'. When TIOCLINUX, use the new_row_size to calc the offset, it maybe larger than the vga_vram_size in vgacon driver, then bad access. Also, if set an larger screenbuf firstly, then set an more larger screenbuf, when copy old_origin to new_origin, a bad access may happen. So, If the screen size larger than vga_vram, resize screen should be failed. This alse fix CVE-2020-8649 and CVE-2020-8647. Linus pointed out that overflow checking seems absent. We're saved by the existing bounds checks in vc_do_resize() with rather strict limits: if (cols > VC_RESIZE_MAXCOL || lines > VC_RESIZE_MAXROW) return -EINVAL; Fixes: 0aec4867dca14 ("[PATCH] SVGATextMode fix") Reference: CVE-2020-8647 and CVE-2020-8649 Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com> [danvet: augment commit message to point out overflow safety] Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20200304022429.37738-1-zhangxiaoxu5@huawei.com
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cpu.c
// SPDX-License-Identifier: GPL-2.0-only
/*
* Generic OPP helper interface for CPU device
*
* Copyright (C) 2009-2014 Texas Instruments Incorporated.
* Nishanth Menon
* Romit Dasgupta
* Kevin Hilman
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/export.h>
#include <linux/slab.h>
#include "opp.h"
#ifdef CONFIG_CPU_FREQ
/**
* dev_pm_opp_init_cpufreq_table() - create a cpufreq table for a device
* @dev: device for which we do this operation
* @table: Cpufreq table returned back to caller
*
* Generate a cpufreq table for a provided device- this assumes that the
* opp table is already initialized and ready for usage.
*
* This function allocates required memory for the cpufreq table. It is
* expected that the caller does the required maintenance such as freeing
* the table as required.
*
* Returns -EINVAL for bad pointers, -ENODEV if the device is not found, -ENOMEM
* if no memory available for the operation (table is not populated), returns 0
* if successful and table is populated.
*
* WARNING: It is important for the callers to ensure refreshing their copy of
* the table if any of the mentioned functions have been invoked in the interim.
*/
int dev_pm_opp_init_cpufreq_table(struct device *dev,
struct cpufreq_frequency_table **table)
{
struct dev_pm_opp *opp;
struct cpufreq_frequency_table *freq_table = NULL;
int i, max_opps, ret = 0;
unsigned long rate;
max_opps = dev_pm_opp_get_opp_count(dev);
if (max_opps <= 0)
return max_opps ? max_opps : -ENODATA;
freq_table = kcalloc((max_opps + 1), sizeof(*freq_table), GFP_KERNEL);
if (!freq_table)
return -ENOMEM;
for (i = 0, rate = 0; i < max_opps; i++, rate++) {
/* find next rate */
opp = dev_pm_opp_find_freq_ceil(dev, &rate);
if (IS_ERR(opp)) {
ret = PTR_ERR(opp);
goto out;
}
freq_table[i].driver_data = i;
freq_table[i].frequency = rate / 1000;
/* Is Boost/turbo opp ? */
if (dev_pm_opp_is_turbo(opp))
freq_table[i].flags = CPUFREQ_BOOST_FREQ;
dev_pm_opp_put(opp);
}
freq_table[i].driver_data = i;
freq_table[i].frequency = CPUFREQ_TABLE_END;
*table = &freq_table[0];
out:
if (ret)
kfree(freq_table);
return ret;
}
EXPORT_SYMBOL_GPL(dev_pm_opp_init_cpufreq_table);
/**
* dev_pm_opp_free_cpufreq_table() - free the cpufreq table
* @dev: device for which we do this operation
* @table: table to free
*
* Free up the table allocated by dev_pm_opp_init_cpufreq_table
*/
void dev_pm_opp_free_cpufreq_table(struct device *dev,
struct cpufreq_frequency_table **table)
{
if (!table)
return;
kfree(*table);
*table = NULL;
}
EXPORT_SYMBOL_GPL(dev_pm_opp_free_cpufreq_table);
#endif /* CONFIG_CPU_FREQ */
void _dev_pm_opp_cpumask_remove_table(const struct cpumask *cpumask,
int last_cpu)
{
struct device *cpu_dev;
int cpu;
WARN_ON(cpumask_empty(cpumask));
for_each_cpu(cpu, cpumask) {
if (cpu == last_cpu)
break;
cpu_dev = get_cpu_device(cpu);
if (!cpu_dev) {
pr_err("%s: failed to get cpu%d device\n", __func__,
cpu);
continue;
}
_dev_pm_opp_find_and_remove_table(cpu_dev);
}
}
/**
* dev_pm_opp_cpumask_remove_table() - Removes OPP table for @cpumask
* @cpumask: cpumask for which OPP table needs to be removed
*
* This removes the OPP tables for CPUs present in the @cpumask.
* This should be used to remove all the OPPs entries associated with
* the cpus in @cpumask.
*/
void dev_pm_opp_cpumask_remove_table(const struct cpumask *cpumask)
{
_dev_pm_opp_cpumask_remove_table(cpumask, -1);
}
EXPORT_SYMBOL_GPL(dev_pm_opp_cpumask_remove_table);
/**
* dev_pm_opp_set_sharing_cpus() - Mark OPP table as shared by few CPUs
* @cpu_dev: CPU device for which we do this operation
* @cpumask: cpumask of the CPUs which share the OPP table with @cpu_dev
*
* This marks OPP table of the @cpu_dev as shared by the CPUs present in
* @cpumask.
*
* Returns -ENODEV if OPP table isn't already present.
*/
int dev_pm_opp_set_sharing_cpus(struct device *cpu_dev,
const struct cpumask *cpumask)
{
struct opp_device *opp_dev;
struct opp_table *opp_table;
struct device *dev;
int cpu, ret = 0;
opp_table = _find_opp_table(cpu_dev);
if (IS_ERR(opp_table))
return PTR_ERR(opp_table);
for_each_cpu(cpu, cpumask) {
if (cpu == cpu_dev->id)
continue;
dev = get_cpu_device(cpu);
if (!dev) {
dev_err(cpu_dev, "%s: failed to get cpu%d device\n",
__func__, cpu);
continue;
}
opp_dev = _add_opp_dev(dev, opp_table);
if (!opp_dev) {
dev_err(dev, "%s: failed to add opp-dev for cpu%d device\n",
__func__, cpu);
continue;
}
/* Mark opp-table as multiple CPUs are sharing it now */
opp_table->shared_opp = OPP_TABLE_ACCESS_SHARED;
}
dev_pm_opp_put_opp_table(opp_table);
return ret;
}
EXPORT_SYMBOL_GPL(dev_pm_opp_set_sharing_cpus);
/**
* dev_pm_opp_get_sharing_cpus() - Get cpumask of CPUs sharing OPPs with @cpu_dev
* @cpu_dev: CPU device for which we do this operation
* @cpumask: cpumask to update with information of sharing CPUs
*
* This updates the @cpumask with CPUs that are sharing OPPs with @cpu_dev.
*
* Returns -ENODEV if OPP table isn't already present and -EINVAL if the OPP
* table's status is access-unknown.
*/
int dev_pm_opp_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
{
struct opp_device *opp_dev;
struct opp_table *opp_table;
int ret = 0;
opp_table = _find_opp_table(cpu_dev);
if (IS_ERR(opp_table))
return PTR_ERR(opp_table);
if (opp_table->shared_opp == OPP_TABLE_ACCESS_UNKNOWN) {
ret = -EINVAL;
goto put_opp_table;
}
cpumask_clear(cpumask);
if (opp_table->shared_opp == OPP_TABLE_ACCESS_SHARED) {
mutex_lock(&opp_table->lock);
list_for_each_entry(opp_dev, &opp_table->dev_list, node)
cpumask_set_cpu(opp_dev->dev->id, cpumask);
mutex_unlock(&opp_table->lock);
} else {
cpumask_set_cpu(cpu_dev->id, cpumask);
}
put_opp_table:
dev_pm_opp_put_opp_table(opp_table);
return ret;
}
EXPORT_SYMBOL_GPL(dev_pm_opp_get_sharing_cpus);
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