syzbot


BUG: unable to handle kernel NULL pointer dereference in alloc_pages_vma

Status: fixed on 2020/07/17 17:58
Subsystems: mm
[Documentation on labels]
Reported-by: syzbot+6b3945fa5b3941822281@syzkaller.appspotmail.com
Fix commit: 3021e69219e2 kcov: check kcov_softirq in kcov_remote_stop()
First crash: 1435d, last: 1435d

Sample crash report:
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD a028b067 P4D a028b067 PUD a6fcd067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 12721 Comm: syz-executor.3 Not tainted 5.7.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__read_once_size include/linux/compiler.h:252 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x3f/0x60 kernel/kcov.c:202
Code: c2 00 01 ff 00 74 11 f7 c2 00 01 00 00 74 35 83 b9 04 14 00 00 00 74 2c 8b 91 e0 13 00 00 83 fa 02 75 21 48 8b 91 e8 13 00 00 <48> 8b 32 48 8d 7e 01 8b 89 e4 13 00 00 48 39 cf 73 08 48 89 44 f2
RSP: 0018:ffffc90008cef6a8 EFLAGS: 00010246
RAX: ffffffff81b0dc66 RBX: ffffc90008cef808 RCX: ffff88805ac0a340
RDX: 0000000000000000 RSI: 000000000003ffff RDI: 0000000000040000
RBP: dffffc0000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffffc90008cef750
FS:  00007f83cea18700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000088054000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __get_vma_policy mm/mempolicy.c:1807 [inline]
 get_vma_policy mm/mempolicy.c:1839 [inline]
 alloc_pages_vma+0x116/0xd10 mm/mempolicy.c:2202
 shmem_alloc_page mm/shmem.c:1503 [inline]
 shmem_alloc_and_acct_page+0x40e/0xbe0 mm/shmem.c:1528
 shmem_getpage_gfp+0x203e/0x2c60 mm/shmem.c:1824
 shmem_fault+0x24b/0x760 mm/shmem.c:2045
 __do_fault+0x138/0x3b0 mm/memory.c:3454
 do_read_fault+0x5a6/0x9e0 mm/memory.c:3847
 do_fault mm/memory.c:3975 [inline]
 handle_pte_fault mm/memory.c:4215 [inline]
 __handle_mm_fault mm/memory.c:4347 [inline]
 handle_mm_fault+0x1d79/0x2910 mm/memory.c:4384
 faultin_page mm/gup.c:888 [inline]
 __get_user_pages+0xbf5/0x16f0 mm/gup.c:1114
 populate_vma_page_range+0x1c8/0x220 mm/gup.c:1453
 __mm_populate+0x283/0x3e0 mm/gup.c:1501
 mm_populate include/linux/mm.h:2596 [inline]
 vm_mmap_pgoff+0x1ab/0x1e0 mm/util.c:511
 ksys_mmap_pgoff+0x111/0x570 mm/mmap.c:1595
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45ca59
Code: 0d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f83cea17c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00000000004f6720 RCX: 000000000045ca59
RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000000020000000
RBP: 000000000078bf00 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000008031 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000755 R14: 00000000004ca40b R15: 00007f83cea186d4
Modules linked in:
CR2: 0000000000000000
---[ end trace 7987dac55036bd30 ]---
RIP: 0010:__read_once_size include/linux/compiler.h:252 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x3f/0x60 kernel/kcov.c:202
Code: c2 00 01 ff 00 74 11 f7 c2 00 01 00 00 74 35 83 b9 04 14 00 00 00 74 2c 8b 91 e0 13 00 00 83 fa 02 75 21 48 8b 91 e8 13 00 00 <48> 8b 32 48 8d 7e 01 8b 89 e4 13 00 00 48 39 cf 73 08 48 89 44 f2
RSP: 0018:ffffc90008cef6a8 EFLAGS: 00010246
RAX: ffffffff81b0dc66 RBX: ffffc90008cef808 RCX: ffff88805ac0a340
RDX: 0000000000000000 RSI: 000000000003ffff RDI: 0000000000040000
RBP: dffffc0000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffffc90008cef750
FS:  00007f83cea18700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000073e914 CR3: 0000000088054000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/06/17 18:44 upstream 7ae77150d94d b9f3810b .config console log report ci-upstream-kasan-gce-smack-root
* Struck through repros no longer work on HEAD.