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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qcom-spmi-sdam.c
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (c) 2017 The Linux Foundation. All rights reserved.
*/
#include <linux/device.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/nvmem-provider.h>
#include <linux/regmap.h>
#define SDAM_MEM_START 0x40
#define REGISTER_MAP_ID 0x40
#define REGISTER_MAP_VERSION 0x41
#define SDAM_SIZE 0x44
#define SDAM_PBS_TRIG_SET 0xE5
#define SDAM_PBS_TRIG_CLR 0xE6
struct sdam_chip {
struct platform_device *pdev;
struct regmap *regmap;
struct nvmem_config sdam_config;
unsigned int base;
unsigned int size;
};
/* read only register offsets */
static const u8 sdam_ro_map[] = {
REGISTER_MAP_ID,
REGISTER_MAP_VERSION,
SDAM_SIZE
};
static bool sdam_is_valid(struct sdam_chip *sdam, unsigned int offset,
size_t len)
{
unsigned int sdam_mem_end = SDAM_MEM_START + sdam->size - 1;
if (!len)
return false;
if (offset >= SDAM_MEM_START && offset <= sdam_mem_end
&& (offset + len - 1) <= sdam_mem_end)
return true;
else if ((offset == SDAM_PBS_TRIG_SET || offset == SDAM_PBS_TRIG_CLR)
&& (len == 1))
return true;
return false;
}
static bool sdam_is_ro(unsigned int offset, size_t len)
{
int i;
for (i = 0; i < ARRAY_SIZE(sdam_ro_map); i++)
if (offset <= sdam_ro_map[i] && (offset + len) > sdam_ro_map[i])
return true;
return false;
}
static int sdam_read(void *priv, unsigned int offset, void *val,
size_t bytes)
{
struct sdam_chip *sdam = priv;
struct device *dev = &sdam->pdev->dev;
int rc;
if (!sdam_is_valid(sdam, offset, bytes)) {
dev_err(dev, "Invalid SDAM offset %#x len=%zd\n",
offset, bytes);
return -EINVAL;
}
rc = regmap_bulk_read(sdam->regmap, sdam->base + offset, val, bytes);
if (rc < 0)
dev_err(dev, "Failed to read SDAM offset %#x len=%zd, rc=%d\n",
offset, bytes, rc);
return rc;
}
static int sdam_write(void *priv, unsigned int offset, void *val,
size_t bytes)
{
struct sdam_chip *sdam = priv;
struct device *dev = &sdam->pdev->dev;
int rc;
if (!sdam_is_valid(sdam, offset, bytes)) {
dev_err(dev, "Invalid SDAM offset %#x len=%zd\n",
offset, bytes);
return -EINVAL;
}
if (sdam_is_ro(offset, bytes)) {
dev_err(dev, "Invalid write offset %#x len=%zd\n",
offset, bytes);
return -EINVAL;
}
rc = regmap_bulk_write(sdam->regmap, sdam->base + offset, val, bytes);
if (rc < 0)
dev_err(dev, "Failed to write SDAM offset %#x len=%zd, rc=%d\n",
offset, bytes, rc);
return rc;
}
static int sdam_probe(struct platform_device *pdev)
{
struct sdam_chip *sdam;
struct nvmem_device *nvmem;
unsigned int val;
int rc;
sdam = devm_kzalloc(&pdev->dev, sizeof(*sdam), GFP_KERNEL);
if (!sdam)
return -ENOMEM;
sdam->regmap = dev_get_regmap(pdev->dev.parent, NULL);
if (!sdam->regmap) {
dev_err(&pdev->dev, "Failed to get regmap handle\n");
return -ENXIO;
}
rc = of_property_read_u32(pdev->dev.of_node, "reg", &sdam->base);
if (rc < 0) {
dev_err(&pdev->dev, "Failed to get SDAM base, rc=%d\n", rc);
return -EINVAL;
}
rc = regmap_read(sdam->regmap, sdam->base + SDAM_SIZE, &val);
if (rc < 0) {
dev_err(&pdev->dev, "Failed to read SDAM_SIZE rc=%d\n", rc);
return -EINVAL;
}
sdam->size = val * 32;
sdam->sdam_config.dev = &pdev->dev;
sdam->sdam_config.name = "spmi_sdam";
sdam->sdam_config.id = pdev->id;
sdam->sdam_config.owner = THIS_MODULE,
sdam->sdam_config.stride = 1;
sdam->sdam_config.word_size = 1;
sdam->sdam_config.reg_read = sdam_read;
sdam->sdam_config.reg_write = sdam_write;
sdam->sdam_config.priv = sdam;
nvmem = devm_nvmem_register(&pdev->dev, &sdam->sdam_config);
if (IS_ERR(nvmem)) {
dev_err(&pdev->dev,
"Failed to register SDAM nvmem device rc=%ld\n",
PTR_ERR(nvmem));
return -ENXIO;
}
dev_dbg(&pdev->dev,
"SDAM base=%#x size=%u registered successfully\n",
sdam->base, sdam->size);
return 0;
}
static const struct of_device_id sdam_match_table[] = {
{ .compatible = "qcom,spmi-sdam" },
{},
};
static struct platform_driver sdam_driver = {
.driver = {
.name = "qcom,spmi-sdam",
.of_match_table = sdam_match_table,
},
.probe = sdam_probe,
};
static int __init sdam_init(void)
{
return platform_driver_register(&sdam_driver);
}
subsys_initcall(sdam_init);
static void __exit sdam_exit(void)
{
return platform_driver_unregister(&sdam_driver);
}
module_exit(sdam_exit);
MODULE_DESCRIPTION("QCOM SPMI SDAM driver");
MODULE_LICENSE("GPL v2");
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