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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aoenet.c
/* Copyright (c) 2013 Coraid, Inc. See COPYING for GPL terms. */
/*
* aoenet.c
* Ethernet portion of AoE driver
*/
#include <linux/gfp.h>
#include <linux/hdreg.h>
#include <linux/blkdev.h>
#include <linux/netdevice.h>
#include <linux/moduleparam.h>
#include <net/net_namespace.h>
#include <asm/unaligned.h>
#include "aoe.h"
#define NECODES 5
static char *aoe_errlist[] =
{
"no such error",
"unrecognized command code",
"bad argument parameter",
"device unavailable",
"config string present",
"unsupported version"
};
enum {
IFLISTSZ = 1024,
};
static char aoe_iflist[IFLISTSZ];
module_param_string(aoe_iflist, aoe_iflist, IFLISTSZ, 0600);
MODULE_PARM_DESC(aoe_iflist, "aoe_iflist=dev1[,dev2...]");
static wait_queue_head_t txwq;
static struct ktstate kts;
#ifndef MODULE
static int __init aoe_iflist_setup(char *str)
{
strncpy(aoe_iflist, str, IFLISTSZ);
aoe_iflist[IFLISTSZ - 1] = '\0';
return 1;
}
__setup("aoe_iflist=", aoe_iflist_setup);
#endif
static spinlock_t txlock;
static struct sk_buff_head skbtxq;
/* enters with txlock held */
static int
tx(int id) __must_hold(&txlock)
{
struct sk_buff *skb;
struct net_device *ifp;
while ((skb = skb_dequeue(&skbtxq))) {
spin_unlock_irq(&txlock);
ifp = skb->dev;
if (dev_queue_xmit(skb) == NET_XMIT_DROP && net_ratelimit())
pr_warn("aoe: packet could not be sent on %s. %s\n",
ifp ? ifp->name : "netif",
"consider increasing tx_queue_len");
spin_lock_irq(&txlock);
}
return 0;
}
int
is_aoe_netif(struct net_device *ifp)
{
register char *p, *q;
register int len;
if (aoe_iflist[0] == '\0')
return 1;
p = aoe_iflist + strspn(aoe_iflist, WHITESPACE);
for (; *p; p = q + strspn(q, WHITESPACE)) {
q = p + strcspn(p, WHITESPACE);
if (q != p)
len = q - p;
else
len = strlen(p); /* last token in aoe_iflist */
if (strlen(ifp->name) == len && !strncmp(ifp->name, p, len))
return 1;
if (q == p)
break;
}
return 0;
}
int
set_aoe_iflist(const char __user *user_str, size_t size)
{
if (size >= IFLISTSZ)
return -EINVAL;
if (copy_from_user(aoe_iflist, user_str, size)) {
printk(KERN_INFO "aoe: copy from user failed\n");
return -EFAULT;
}
aoe_iflist[size] = 0x00;
return 0;
}
void
aoenet_xmit(struct sk_buff_head *queue)
{
struct sk_buff *skb, *tmp;
ulong flags;
skb_queue_walk_safe(queue, skb, tmp) {
__skb_unlink(skb, queue);
spin_lock_irqsave(&txlock, flags);
skb_queue_tail(&skbtxq, skb);
spin_unlock_irqrestore(&txlock, flags);
wake_up(&txwq);
}
}
/*
* (1) len doesn't include the header by default. I want this.
*/
static int
aoenet_rcv(struct sk_buff *skb, struct net_device *ifp, struct packet_type *pt, struct net_device *orig_dev)
{
struct aoe_hdr *h;
struct aoe_atahdr *ah;
u32 n;
int sn;
if (dev_net(ifp) != &init_net)
goto exit;
skb = skb_share_check(skb, GFP_ATOMIC);
if (skb == NULL)
return 0;
if (!is_aoe_netif(ifp))
goto exit;
skb_push(skb, ETH_HLEN); /* (1) */
sn = sizeof(*h) + sizeof(*ah);
if (skb->len >= sn) {
sn -= skb_headlen(skb);
if (sn > 0 && !__pskb_pull_tail(skb, sn))
goto exit;
}
h = (struct aoe_hdr *) skb->data;
n = get_unaligned_be32(&h->tag);
if ((h->verfl & AOEFL_RSP) == 0 || (n & 1<<31))
goto exit;
if (h->verfl & AOEFL_ERR) {
n = h->err;
if (n > NECODES)
n = 0;
if (net_ratelimit())
printk(KERN_ERR
"%s%d.%d@%s; ecode=%d '%s'\n",
"aoe: error packet from ",
get_unaligned_be16(&h->major),
h->minor, skb->dev->name,
h->err, aoe_errlist[n]);
goto exit;
}
switch (h->cmd) {
case AOECMD_ATA:
/* ata_rsp may keep skb for later processing or give it back */
skb = aoecmd_ata_rsp(skb);
break;
case AOECMD_CFG:
aoecmd_cfg_rsp(skb);
break;
default:
if (h->cmd >= AOECMD_VEND_MIN)
break; /* don't complain about vendor commands */
pr_info("aoe: unknown AoE command type 0x%02x\n", h->cmd);
break;
}
if (!skb)
return 0;
exit:
dev_kfree_skb(skb);
return 0;
}
static struct packet_type aoe_pt __read_mostly = {
.type = __constant_htons(ETH_P_AOE),
.func = aoenet_rcv,
};
int __init
aoenet_init(void)
{
skb_queue_head_init(&skbtxq);
init_waitqueue_head(&txwq);
spin_lock_init(&txlock);
kts.lock = &txlock;
kts.fn = tx;
kts.waitq = &txwq;
kts.id = 0;
snprintf(kts.name, sizeof(kts.name), "aoe_tx%d", kts.id);
if (aoe_ktstart(&kts))
return -EAGAIN;
dev_add_pack(&aoe_pt);
return 0;
}
void
aoenet_exit(void)
{
aoe_ktstop(&kts);
skb_queue_purge(&skbtxq);
dev_remove_pack(&aoe_pt);
}
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