Messages in this thread | | | Date | Mon, 21 Nov 2022 08:34:33 -0800 | Subject | Re: BUG: unable to handle kernel NULL pointer dereference in alloc_buddy_hugetlb_folio | From | Sidhartha Kumar <> |
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On 11/21/22 6:21 AM, Wei Chen wrote: > Dear Linux Developer, > > Recently when using our tool to fuzz kernel, the following crash was triggered. > > HEAD commit: 147307c69ba > git tree: upstream > compiler: clang 12.0.0 > console output: > https://drive.google.com/file/d/1b2z08RYnxoR5I8UiwqaMpG9E-dYgDTcL/view?usp=share_link > kernel config: https://drive.google.com/file/d/1NAf4S43d9VOKD52xbrqw-PUP1Mbj8z-S/view?usp=share_link > Syz reproducer: > https://drive.google.com/file/d/18vNqAHwkVoyx5Db2qnswcaiT-prLx_rx/view?usp=share_link > > Unfortunately, if we transform the syz reproducer to C reproducer with > syz-prog2c, the crash would not happen. Please consider to use > syz-execprog and syz-executor to reproduce the crash. > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: Wei Chen <harperchen1110@gmail.com> > > BUG: kernel NULL pointer dereference, address: 0000000000000008
It looks like this is caused by what John mentioned here[1]. I will send out a new version of this patch with the fix.
Thanks,
Sidhartha Kumar
[1] https://lore.kernel.org/linux-mm/03ca2e41-28d3-c546-4347-5dee7b7dca9b@oracle.com/T/#m6312d55610697df44d00c41d60fa8af9d3239891
> #PF: supervisor read access in kernel mode > #PF: error_code(0x0000) - not-present page > PGD a9b2067 P4D a9b2067 PUD ab02067 PMD 0 > Oops: 0000 [#1] PREEMPT SMP > CPU: 0 PID: 30461 Comm: syz-executor.0 Not tainted 6.1.0-rc5-next-20221118 #2 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS > rel-1.13.0-48-gd9c812dda519-prebuilt.qemu.org 04/01/2014 > RIP: 0010:_compound_head include/linux/page-flags.h:250 [inline] > RIP: 0010:alloc_buddy_hugetlb_folio+0x1bd/0x2b0 mm/hugetlb.c:2009 > Code: ff 74 16 8b 04 24 34 01 75 0f e8 ae 04 d8 ff 49 63 c5 3e 49 0f > ab 07 eb 05 e8 9f 04 d8 ff 45 31 f6 49 8d 7e 08 e8 23 84 eb ff <49> 8b > 5e 08 48 89 de 48 83 e6 01 31 ff e8 31 09 d8 ff 48 89 d8 48 > RSP: 0018:ffffc90002823bd0 EFLAGS: 00010246 > RAX: ffffffff814fad41 RBX: 0000000000000009 RCX: 0000000000040000 > RDX: ffffc90000afd000 RSI: 0000000000000ab3 RDI: 0000000000000008 > RBP: 0000000000146cca R08: 0001ffffffffffff R09: 0000000000000000 > R10: 0001ffffffffffff R11: ffff88812663a000 R12: 0000000000000000 > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > FS: 00007f7190641700(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000000008 CR3: 000000000ab00000 CR4: 00000000003506f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > <TASK> > alloc_fresh_hugetlb_folio+0x73/0x370 mm/hugetlb.c:2030 > alloc_surplus_huge_page+0xb6/0x1a0 mm/hugetlb.c:2245 > alloc_buddy_huge_page_with_mpol mm/hugetlb.c:2321 [inline] > alloc_huge_page+0x9d6/0x1620 mm/hugetlb.c:2937 > hugetlbfs_fallocate+0x57f/0xd70 fs/hugetlbfs/inode.c:865 > vfs_fallocate+0x486/0x710 fs/open.c:323 > ksys_fallocate fs/open.c:346 [inline] > __do_sys_fallocate fs/open.c:354 [inline] > __se_sys_fallocate fs/open.c:352 [inline] > __x64_sys_fallocate+0x75/0xc0 fs/open.c:352 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > RIP: 0033:0x4697f9 > Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007f7190640c48 EFLAGS: 00000246 ORIG_RAX: 000000000000011d > RAX: ffffffffffffffda RBX: 000000000077bf80 RCX: 00000000004697f9 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 > RBP: 00007f7190640c80 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000008800000 R11: 0000000000000246 R12: 0000000000000005 > R13: 0000000000000000 R14: 000000000077bf80 R15: 00007ffcccf17d70 > </TASK> > Modules linked in: > CR2: 0000000000000008 > ---[ end trace 0000000000000000 ]--- > RIP: 0010:_compound_head include/linux/page-flags.h:250 [inline] > RIP: 0010:alloc_buddy_hugetlb_folio+0x1bd/0x2b0 mm/hugetlb.c:2009 > Code: ff 74 16 8b 04 24 34 01 75 0f e8 ae 04 d8 ff 49 63 c5 3e 49 0f > ab 07 eb 05 e8 9f 04 d8 ff 45 31 f6 49 8d 7e 08 e8 23 84 eb ff <49> 8b > 5e 08 48 89 de 48 83 e6 01 31 ff e8 31 09 d8 ff 48 89 d8 48 > RSP: 0018:ffffc90002823bd0 EFLAGS: 00010246 > RAX: ffffffff814fad41 RBX: 0000000000000009 RCX: 0000000000040000 > RDX: ffffc90000afd000 RSI: 0000000000000ab3 RDI: 0000000000000008 > RBP: 0000000000146cca R08: 0001ffffffffffff R09: 0000000000000000 > R10: 0001ffffffffffff R11: ffff88812663a000 R12: 0000000000000000 > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > FS: 00007f7190641700(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000000008 CR3: 000000000ab00000 CR4: 00000000003506f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > ---------------- > Code disassembly (best guess): > 0: ff 74 16 8b pushq -0x75(%rsi,%rdx,1) > 4: 04 24 add $0x24,%al > 6: 34 01 xor $0x1,%al > 8: 75 0f jne 0x19 > a: e8 ae 04 d8 ff callq 0xffd804bd > f: 49 63 c5 movslq %r13d,%rax > 12: 3e 49 0f ab 07 bts %rax,%ds:(%r15) > 17: eb 05 jmp 0x1e > 19: e8 9f 04 d8 ff callq 0xffd804bd > 1e: 45 31 f6 xor %r14d,%r14d > 21: 49 8d 7e 08 lea 0x8(%r14),%rdi > 25: e8 23 84 eb ff callq 0xffeb844d > * 2a: 49 8b 5e 08 mov 0x8(%r14),%rbx <-- trapping instruction > 2e: 48 89 de mov %rbx,%rsi > 31: 48 83 e6 01 and $0x1,%rsi > 35: 31 ff xor %edi,%edi > 37: e8 31 09 d8 ff callq 0xffd8096d > 3c: 48 89 d8 mov %rbx,%rax > 3f: 48 rex.W > > Best, > Wei >
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