On 2020/7/30 21:38, Jiri Slaby wrote:
On 30. 07. 20, 15:24, Yang Yingliang wrote:
On 2020/7/30 19:04, Jiri Slaby wrote:
On 13. 07. 20, 12:57, Yang Yingliang wrote:
I got a slab-out-of-bounds report when I doing fuzz test.
[ 334.989515]
==================================================================
[ 334.989577] BUG: KASAN: slab-out-of-bounds in
vgacon_scroll+0x57a/0x8ed
[ 334.989588] Write of size 1766 at addr ffff8883de69ff3e by task
test/2658
[ 334.989593]
[ 334.989608] CPU: 3 PID: 2658 Comm: test Not tainted
5.7.0-rc5-00005-g152036d1379f #789
[ 334.989617] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
[ 334.989624] Call Trace:
[ 334.989646] dump_stack+0xe4/0x14e
[ 334.989676] print_address_description.constprop.5+0x3f/0x60
[ 334.989699] ? vgacon_scroll+0x57a/0x8ed
[ 334.989710] __kasan_report.cold.8+0x92/0xaf
[ 334.989735] ? vgacon_scroll+0x57a/0x8ed
[ 334.989761] kasan_report+0x37/0x50
[ 334.989789] check_memory_region+0x1c1/0x1e0
[ 334.989806] memcpy+0x38/0x60
[ 334.989824] vgacon_scroll+0x57a/0x8ed
[ 334.989876] con_scroll+0x4ef/0x5e0
...
Because vgacon_scrollback_cur->tail plus memcpy size is greater than
vgacon_scrollback_cur->size. Fix this by checking the memcpy size.
Reported-by: Hulk Robot <hul...@huawei.com>
Signed-off-by: Yang Yingliang <yangyingli...@huawei.com>
---
drivers/video/console/vgacon.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/drivers/video/console/vgacon.c
b/drivers/video/console/vgacon.c
index 998b0de1812f..b51ffb9a208d 100644
--- a/drivers/video/console/vgacon.c
+++ b/drivers/video/console/vgacon.c
@@ -243,6 +243,7 @@ static void vgacon_scrollback_startup(void)
static void vgacon_scrollback_update(struct vc_data *c, int t, int
count)
{
void *p;
+ int size;
if (!vgacon_scrollback_cur->data ||
!vgacon_scrollback_cur->size ||
c->vc_num != fg_console)
@@ -251,13 +252,17 @@ static void vgacon_scrollback_update(struct
vc_data *c, int t, int count)
p = (void *) (c->vc_origin + t * c->vc_size_row);
while (count--) {
+ size = vgacon_scrollback_cur->size -
vgacon_scrollback_cur->tail;
+ if (size > c->vc_size_row)
+ size = c->vc_size_row;
+
scr_memcpyw(vgacon_scrollback_cur->data +
vgacon_scrollback_cur->tail,
- p, c->vc_size_row);
+ p, size);
Are you sure the consumer can handle split lines? As vgacon_scrolldelta
(soff in particular) looks to me like it doesn't.
Have you tested you patch? I mean with soft scrollback on the vga
console?
I only test the patch with the reproduce program.
Out of curiosity, what is it doing? Resize and then scroll by \n (line
feed)? Can you share it?
// autogenerated by syzkaller (https://github.com/google/syzkaller)
#define _GNU_SOURCE
#include <dirent.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/prctl.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>
static void sleep_ms(uint64_t ms)
{
usleep(ms * 1000);
}
static uint64_t current_time_ms(void)
{
struct timespec ts;
if (clock_gettime(CLOCK_MONOTONIC, &ts))
exit(1);
return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
}
static bool write_file(const char* file, const char* what, ...)
{
char buf[1024];
va_list args;
va_start(args, what);
vsnprintf(buf, sizeof(buf), what, args);
va_end(args);
buf[sizeof(buf) - 1] = 0;
int len = strlen(buf);
int fd = open(file, O_WRONLY | O_CLOEXEC);
if (fd == -1)
return false;
if (write(fd, buf, len) != len) {
int err = errno;
close(fd);
errno = err;
return false;
}
close(fd);
return true;
}
static long syz_open_dev(volatile long a0, volatile long a1, volatile long a2)
{
if (a0 == 0xc || a0 == 0xb) {
char buf[128];
sprintf(buf, "/dev/%s/%d:%d", a0 == 0xc ? "char" : "block",
(uint8_t)a1, (uint8_t)a2);
return open(buf, O_RDWR, 0);
} else {
char buf[1024];
char* hash;
strncpy(buf, (char*)a0, sizeof(buf) - 1);
buf[sizeof(buf) - 1] = 0;
while ((hash = strchr(buf, '#'))) {
*hash = '0' + (char)(a1 % 10);
a1 /= 10;
}
return open(buf, a2, 0);
}
}
static void kill_and_wait(int pid, int* status)
{
kill(-pid, SIGKILL);
kill(pid, SIGKILL);
int i;
for (i = 0; i < 100; i++) {
if (waitpid(-1, status, WNOHANG | __WALL) == pid)
return;
usleep(1000);
}
DIR* dir = opendir("/sys/fs/fuse/connections");
if (dir) {
for (;;) {
struct dirent* ent = readdir(dir);
if (!ent)
break;
if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name,
"..") == 0)
continue;
char abort[300];
snprintf(abort, sizeof(abort),
"/sys/fs/fuse/connections/%s/abort", ent->d_name);
int fd = open(abort, O_WRONLY);
if (fd == -1) {
continue;
}
if (write(fd, abort, 1) < 0) {
}
close(fd);
}
closedir(dir);
} else {
}
while (waitpid(-1, status, __WALL) != pid) {
}
}
static void setup_test()
{
prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
setpgrp();
write_file("/proc/self/oom_score_adj", "1000");
}
static void execute_one(void);
#define WAIT_FLAGS __WALL
static void loop(void)
{
int iter;
for (iter = 0;; iter++) {
int pid = fork();
if (pid < 0)
exit(1);
if (pid == 0) {
setup_test();
execute_one();
exit(0);
}
int status = 0;
uint64_t start = current_time_ms();
for (;;) {
if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid)
break;
sleep_ms(1);
if (current_time_ms() - start < 5 * 1000)
continue;
kill_and_wait(pid, &status);
break;
}
}
}
uint64_t r[1] = {0xffffffffffffffff};
void execute_one(void)
{
intptr_t res = 0;
res = syz_open_dev(0xc, 4, 1);
if (res != -1)
r[0] = res;
*(uint16_t*)0x20000000 = 0xc;
*(uint16_t*)0x20000002 = 0x373;
*(uint16_t*)0x20000004 = 0x1442;
syscall(__NR_ioctl, r[0], 0x5609ul, 0x20000000ul);
memcpy((void*)0x20003500,
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897);
syscall(__NR_write, r[0], 0x20003500ul, 0x381ul);
}
int main(void)
{
syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 3ul, 0x32ul, -1,
0);
loop();
return 0;
}
thanks,
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