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Message-ID: <4937ffd4-f30a-4bdb-9166-6aebb19ca950@grimberg.me>
Date: Sun, 16 Jun 2024 12:24:28 +0300
From: Sagi Grimberg <sagi@...mberg.me>
To: kernel test robot <oliver.sang@...el.com>,
Matthew Wilcox <willy@...radead.org>
Cc: oe-lkp@...ts.linux.dev, lkp@...el.com, netdev@...r.kernel.org,
Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>
Subject: Re: [PATCH] net: micro-optimize skb_datagram_iter
On 16/06/2024 11:06, kernel test robot wrote:
>
> Hello,
>
> kernel test robot noticed "kernel_BUG_at_mm/usercopy.c" on:
>
> commit: 18f0423b9eccb781310af6709ceebf654175af14 ("[PATCH] net: micro-optimize skb_datagram_iter")
> url: https://github.com/intel-lab-lkp/linux/commits/Sagi-Grimberg/net-micro-optimize-skb_datagram_iter/20240613-193620
> base: https://git.kernel.org/cgit/linux/kernel/git/davem/net.git b60b1bdc1888f51da7a2a22c48c5f1eb2bd12e97
> patch link: https://lore.kernel.org/all/20240613113504.1079860-1-sagi@grimberg.me/
> patch subject: [PATCH] net: micro-optimize skb_datagram_iter
>
> in testcase: boot
>
> compiler: gcc-8
> test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G
>
> (please refer to attached dmesg/kmsg for entire log/backtrace)
>
>
> +------------------------------------------+------------+------------+
> | | b60b1bdc18 | 18f0423b9e |
> +------------------------------------------+------------+------------+
> | boot_successes | 6 | 0 |
> | boot_failures | 0 | 6 |
> | kernel_BUG_at_mm/usercopy.c | 0 | 6 |
> | Oops:invalid_opcode:#[##]PREEMPT_SMP | 0 | 6 |
> | EIP:usercopy_abort | 0 | 6 |
> | Kernel_panic-not_syncing:Fatal_exception | 0 | 6 |
> +------------------------------------------+------------+------------+
>
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <oliver.sang@...el.com>
> | Closes: https://lore.kernel.org/oe-lkp/202406161539.b5ff7b20-oliver.sang@intel.com
>
>
> [ 13.495377][ T189] ------------[ cut here ]------------
> [ 13.495862][ T189] kernel BUG at mm/usercopy.c:102!
> [ 13.496372][ T189] Oops: invalid opcode: 0000 [#1] PREEMPT SMP
> [ 13.496927][ T189] CPU: 0 PID: 189 Comm: systemctl Not tainted 6.10.0-rc2-00258-g18f0423b9ecc #1
> [ 13.497741][ T189] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> [ 13.498663][ T189] EIP: usercopy_abort (mm/usercopy.c:102 (discriminator 12))
> [ 13.499424][ T194] usercopy: Kernel memory exposure attempt detected from kmap (offset 0, size 8192)!
Hmm, not sure I understand exactly why changing kmap() to
kmap_local_page() expose this,
but it looks like mm/usercopy does not like size=8192 when copying for
the skb frag.
quick git browse directs to:
--
commit 4e140f59d285c1ca1e5c81b4c13e27366865bd09
Author: Matthew Wilcox (Oracle) <willy@...radead.org>
Date: Mon Jan 10 23:15:27 2022 +0000
mm/usercopy: Check kmap addresses properly
If you are copying to an address in the kmap region, you may not copy
across a page boundary, no matter what the size of the underlying
allocation. You can't kmap() a slab page because slab pages always
come from low memory.
Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Acked-by: Kees Cook <keescook@...omium.org>
Signed-off-by: Kees Cook <keescook@...omium.org>
Link:
https://lore.kernel.org/r/20220110231530.665970-2-willy@infradead.org
--
CCing willy.
The documentation suggest that under single-context usage kmap() can be
freely converted
to kmap_local_page()? But seems that when using kmap() the size is not
an issue, still trying to
understand why.
> [ 13.499647][ T189] Code: d6 89 44 24 0c 0f 45 cf 8b 7d 0c 89 74 24 10 89 4c 24 04 c7 04 24 a4 55 8a d6 89 7c 24 20 8b 7d 08 89 7c 24 1c e8 20 3c df ff <0f> 0b b8 80 91 d7 d6 e8 a8 de 68 00 ba 3d 17 86 d6 89 55 f0 89 d6
> All code
> ========
> 0: d6 (bad)
> 1: 89 44 24 0c mov %eax,0xc(%rsp)
> 5: 0f 45 cf cmovne %edi,%ecx
> 8: 8b 7d 0c mov 0xc(%rbp),%edi
> b: 89 74 24 10 mov %esi,0x10(%rsp)
> f: 89 4c 24 04 mov %ecx,0x4(%rsp)
> 13: c7 04 24 a4 55 8a d6 movl $0xd68a55a4,(%rsp)
> 1a: 89 7c 24 20 mov %edi,0x20(%rsp)
> 1e: 8b 7d 08 mov 0x8(%rbp),%edi
> 21: 89 7c 24 1c mov %edi,0x1c(%rsp)
> 25: e8 20 3c df ff call 0xffffffffffdf3c4a
> 2a:* 0f 0b ud2 <-- trapping instruction
> 2c: b8 80 91 d7 d6 mov $0xd6d79180,%eax
> 31: e8 a8 de 68 00 call 0x68dede
> 36: ba 3d 17 86 d6 mov $0xd686173d,%edx
> 3b: 89 55 f0 mov %edx,-0x10(%rbp)
> 3e: 89 d6 mov %edx,%esi
>
> Code starting with the faulting instruction
> ===========================================
> 0: 0f 0b ud2
> 2: b8 80 91 d7 d6 mov $0xd6d79180,%eax
> 7: e8 a8 de 68 00 call 0x68deb4
> c: ba 3d 17 86 d6 mov $0xd686173d,%edx
> 11: 89 55 f0 mov %edx,-0x10(%rbp)
> 14: 89 d6 mov %edx,%esi
> [ 13.500502][ T194] ------------[ cut here ]------------
> [ 13.502187][ T189] EAX: 00000052 EBX: d680da68 ECX: e0435480 EDX: 01000232
> [ 13.502666][ T194] kernel BUG at mm/usercopy.c:102!
> [ 13.503236][ T189] ESI: d686173d EDI: 00000000 EBP: ece37c44 ESP: ece37c10
> [ 13.504266][ T189] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 EFLAGS: 00010286
> [ 13.504856][ T189] CR0: 80050033 CR2: 0135eb6c CR3: 2beff000 CR4: 000406d0
> [ 13.505464][ T189] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
> [ 13.506083][ T189] DR6: fffe0ff0 DR7: 00000400
> [ 13.506495][ T189] Call Trace:
> [ 13.506795][ T189] ? show_regs (arch/x86/kernel/dumpstack.c:479)
> [ 13.507187][ T189] ? __die_body (arch/x86/kernel/dumpstack.c:421)
> [ 13.507576][ T189] ? die (arch/x86/kernel/dumpstack.c:449)
> [ 13.507894][ T189] ? do_trap (arch/x86/kernel/traps.c:114 arch/x86/kernel/traps.c:155)
> [ 13.508270][ T189] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4300 kernel/locking/lockdep.c:4359 kernel/locking/lockdep.c:4311)
> [ 13.508783][ T189] ? do_error_trap (arch/x86/include/asm/traps.h:58 arch/x86/kernel/traps.c:176)
> [ 13.509182][ T189] ? usercopy_abort (mm/usercopy.c:102 (discriminator 12))
> [ 13.509588][ T189] ? exc_overflow (arch/x86/kernel/traps.c:252)
> [ 13.509983][ T189] ? exc_invalid_op (arch/x86/kernel/traps.c:267)
> [ 13.510396][ T189] ? usercopy_abort (mm/usercopy.c:102 (discriminator 12))
> [ 13.510797][ T189] ? handle_exception (arch/x86/entry/entry_32.S:1054)
> [ 13.511242][ T189] ? exc_overflow (arch/x86/kernel/traps.c:252)
> [ 13.511646][ T189] ? usercopy_abort (mm/usercopy.c:102 (discriminator 12))
> [ 13.512070][ T189] ? exc_overflow (arch/x86/kernel/traps.c:252)
> [ 13.512434][ T189] ? usercopy_abort (mm/usercopy.c:102 (discriminator 12))
> [ 13.512832][ T189] __check_object_size (mm/usercopy.c:180 mm/usercopy.c:251 mm/usercopy.c:213)
> [ 13.513275][ T189] simple_copy_to_iter (include/linux/uio.h:196 net/core/datagram.c:513)
> [ 13.513693][ T189] __skb_datagram_iter (net/core/datagram.c:424 (discriminator 1))
> [ 13.514138][ T189] skb_copy_datagram_iter (net/core/datagram.c:529)
> [ 13.514606][ T189] ? skb_free_datagram (net/core/datagram.c:512)
> [ 13.515028][ T189] ? scm_stat_del (net/unix/af_unix.c:2883)
> [ 13.515429][ T189] unix_stream_read_actor (net/unix/af_unix.c:2889)
> [ 13.515884][ T189] unix_stream_read_generic (net/unix/af_unix.c:2805)
> [ 13.516377][ T189] ? cma_for_each_area (mm/page_ext.c:518)
> [ 13.516826][ T189] ? unix_stream_splice_read (net/unix/af_unix.c:2907)
> [ 13.517301][ T189] unix_stream_recvmsg (net/unix/af_unix.c:2923)
> [ 13.517720][ T189] ? scm_stat_del (net/unix/af_unix.c:2883)
> [ 13.518108][ T189] ____sys_recvmsg (net/socket.c:1046 net/socket.c:1068 net/socket.c:2804)
> [ 13.518527][ T189] ? import_iovec (lib/iov_iter.c:1348)
> [ 13.518930][ T189] ? copy_msghdr_from_user (net/socket.c:2525)
> [ 13.519396][ T189] ___sys_recvmsg (net/socket.c:2846)
> [ 13.519811][ T189] ? __fdget (fs/file.c:1160)
> [ 13.520186][ T189] ? sockfd_lookup_light (net/socket.c:558)
> [ 13.520643][ T189] __sys_recvmsg (include/linux/file.h:34 net/socket.c:2878)
> [ 13.521046][ T189] __ia32_sys_socketcall (net/socket.c:3173 net/socket.c:3077 net/socket.c:3077)
> [ 13.521513][ T189] ia32_sys_call (arch/x86/entry/syscall_32.c:42)
> [ 13.521923][ T189] __do_fast_syscall_32 (arch/x86/entry/common.c:165 arch/x86/entry/common.c:386)
> [ 13.522362][ T189] do_fast_syscall_32 (arch/x86/entry/common.c:411)
> [ 13.522787][ T189] do_SYSENTER_32 (arch/x86/entry/common.c:450)
> [ 13.523188][ T189] entry_SYSENTER_32 (arch/x86/entry/entry_32.S:836)
> [ 13.523613][ T189] EIP: 0xb7ee6579
> [ 13.523933][ T189] Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d 76 00 58 b8 77 00 00 00 cd 80 90 8d 76
> All code
> ========
> 0: b8 01 10 06 03 mov $0x3061001,%eax
> 5: 74 b4 je 0xffffffffffffffbb
> 7: 01 10 add %edx,(%rax)
> 9: 07 (bad)
> a: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi
> e: 10 08 adc %cl,(%rax)
> 10: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi
> ...
> 20: 00 51 52 add %dl,0x52(%rcx)
> 23: 55 push %rbp
> 24:* 89 e5 mov %esp,%ebp <-- trapping instruction
> 26: 0f 34 sysenter
> 28: cd 80 int $0x80
> 2a: 5d pop %rbp
> 2b: 5a pop %rdx
> 2c: 59 pop %rcx
> 2d: c3 ret
> 2e: 90 nop
> 2f: 90 nop
> 30: 90 nop
> 31: 90 nop
> 32: 8d 76 00 lea 0x0(%rsi),%esi
> 35: 58 pop %rax
> 36: b8 77 00 00 00 mov $0x77,%eax
> 3b: cd 80 int $0x80
> 3d: 90 nop
> 3e: 8d .byte 0x8d
> 3f: 76 .byte 0x76
>
> Code starting with the faulting instruction
> ===========================================
> 0: 5d pop %rbp
> 1: 5a pop %rdx
> 2: 59 pop %rcx
> 3: c3 ret
> 4: 90 nop
> 5: 90 nop
> 6: 90 nop
> 7: 90 nop
> 8: 8d 76 00 lea 0x0(%rsi),%esi
> b: 58 pop %rax
> c: b8 77 00 00 00 mov $0x77,%eax
> 11: cd 80 int $0x80
> 13: 90 nop
> 14: 8d .byte 0x8d
> 15: 76 .byte 0x76
> [ 13.525624][ T189] EAX: ffffffda EBX: 00000011 ECX: bfdf5450 EDX: 00000000
> [ 13.526233][ T189] ESI: b7c46000 EDI: bfdf54ac EBP: bfdf54a8 ESP: bfdf5440
> [ 13.526853][ T189] DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b EFLAGS: 00000286
> [ 13.527519][ T189] Modules linked in: i2c_piix4(+) agpgart(+) qemu_fw_cfg button fuse drm drm_panel_orientation_quirks ip_tables
> [ 13.528566][ T194] Oops: invalid opcode: 0000 [#2] PREEMPT SMP
> [ 13.528804][ T189] ---[ end trace 0000000000000000 ]---
> [ 13.529217][ T194] CPU: 1 PID: 194 Comm: systemctl Tainted: G D 6.10.0-rc2-00258-g18f0423b9ecc #1
> [ 13.529725][ T189] EIP: usercopy_abort (mm/usercopy.c:102 (discriminator 12))
> [ 13.530536][ T194] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> [ 13.531060][ T189] Code: d6 89 44 24 0c 0f 45 cf 8b 7d 0c 89 74 24 10 89 4c 24 04 c7 04 24 a4 55 8a d6 89 7c 24 20 8b 7d 08 89 7c 24 1c e8 20 3c df ff <0f> 0b b8 80 91 d7 d6 e8 a8 de 68 00 ba 3d 17 86 d6 89 55 f0 89 d6
> All code
> ========
> 0: d6 (bad)
> 1: 89 44 24 0c mov %eax,0xc(%rsp)
> 5: 0f 45 cf cmovne %edi,%ecx
> 8: 8b 7d 0c mov 0xc(%rbp),%edi
> b: 89 74 24 10 mov %esi,0x10(%rsp)
> f: 89 4c 24 04 mov %ecx,0x4(%rsp)
> 13: c7 04 24 a4 55 8a d6 movl $0xd68a55a4,(%rsp)
> 1a: 89 7c 24 20 mov %edi,0x20(%rsp)
> 1e: 8b 7d 08 mov 0x8(%rbp),%edi
> 21: 89 7c 24 1c mov %edi,0x1c(%rsp)
> 25: e8 20 3c df ff call 0xffffffffffdf3c4a
> 2a:* 0f 0b ud2 <-- trapping instruction
> 2c: b8 80 91 d7 d6 mov $0xd6d79180,%eax
> 31: e8 a8 de 68 00 call 0x68dede
> 36: ba 3d 17 86 d6 mov $0xd686173d,%edx
> 3b: 89 55 f0 mov %edx,-0x10(%rbp)
> 3e: 89 d6 mov %edx,%esi
>
> Code starting with the faulting instruction
> ===========================================
> 0: 0f 0b ud2
> 2: b8 80 91 d7 d6 mov $0xd6d79180,%eax
> 7: e8 a8 de 68 00 call 0x68deb4
> c: ba 3d 17 86 d6 mov $0xd686173d,%edx
> 11: 89 55 f0 mov %edx,-0x10(%rbp)
> 14: 89 d6 mov %edx,%esi
>
>
> The kernel config and materials to reproduce are available at:
> https://download.01.org/0day-ci/archive/20240616/202406161539.b5ff7b20-oliver.sang@intel.com
>
>
>
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