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SubjectRE: [bug report] memory corruption panic caused by SG_IO ioctl()
Date
Doug, 

On 2018-08-03 04:46 AM, Wanlong Gao wrote:
> Hi Martinand all folks,
>
>
>> Recently we find a kernel panic with memory corruption caused by SG_IO ioctl(),
>> and it can be easily reproduced by running following reproducer about
>> minutes,any idea?

> Which kernel?

We've tested with 4.17.11 and 4.18.rc7 and both reproduced.

> And what are the underlying devices (e.g. does /dev/sg0 refer to a SATA disk,
> a real SCSI disk (SAS for example), USB mass storage, etc)?

We tested in a qemu-kvm guest and the sg0 refer to a virtual SATA disk.

> Also can you get a copy of the kernel panic?

Since the call traces are different every time it reproduced, that I didn't paste the
call trace or the vmcore, but this reproducer is very useful and I believe you can reproduce
it easily using the following code.

Thanks,
Wanlong

> Doug Gilbert

>
> C reproducer:
>
> // autogenerated by syzkaller (http://github.com/google/syzkaller)
>
> #define _GNU_SOURCE
>
> #include <endian.h>
>
> #include <sys/syscall.h>
>
> #include <unistd.h>
>
> #include <fcntl.h>
>
> #include <stdio.h>
>
> #include <string.h>
>
> #include <sys/stat.h>
>
> #include <stdint.h>
>
> #include <string.h>
>
> static uintptr_t syz_open_dev(uintptr_t a0, uintptr_t a1, uintptr_t 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 execute_one();
>
> extern unsigned long long procid;
>
> void loop()
>
> {
>
> while (1) {
>
> execute_one();
>
> }
>
> }
>
> uint64_t r[1] = {0xffffffffffffffff};
>
> void execute_one()
>
> {
>
> long res = 0;
>
> memcpy((void*)0x20000040, "/dev/sg#", 9);
>
> res = syz_open_dev(0x20000040, 0, 0);
>
> if (res != -1)
>
> r[0] = res;
>
> *(uint32_t*)0x200002c0 = 0x53;
>
> *(uint32_t*)0x200002c4 = 0;
>
> *(uint8_t*)0x200002c8 = 0xd;
>
> *(uint8_t*)0x200002c9 = 0;
>
> *(uint16_t*)0x200002ca = 0;
>
> *(uint32_t*)0x200002cc = 0x95;
>
> *(uint64_t*)0x200002d0 = 0x20000080;
>
> *(uint64_t*)0x200002d8 = 0x20000000;
>
> memcpy((void*)0x20000000,
> "\x08\xf0\xa8\x77\xd3\xbe\x87\x5d\xda\x65\x79\x3f\xc7", 13);
>
> *(uint64_t*)0x200002e0 = 0x20000180;
>
> *(uint32_t*)0x200002e8 = 0x8001;
>
> *(uint32_t*)0x200002ec = 0x10024;
>
> *(uint32_t*)0x200002f0 = -1;
>
> *(uint64_t*)0x200002f4 = 0x20000280;
>
> *(uint8_t*)0x200002fc = 0;
>
> *(uint8_t*)0x200002fd = 0;
>
> *(uint8_t*)0x200002fe = 0;
>
> *(uint8_t*)0x200002ff = 0;
>
> *(uint16_t*)0x20000300 = 0;
>
> *(uint16_t*)0x20000302 = 0;
>
> *(uint32_t*)0x20000304 = 0;
>
> *(uint32_t*)0x20000308 = 0;
>
> *(uint32_t*)0x2000030c = 0;
>
> syscall(__NR_ioctl, r[0], 0x2285, 0x200002c0);
>
> }
>
> int main()
>
> {
>
> syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0);
>
> for (;;) {
>
> loop();
>
> }
>
> }
>

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