WARNING: kmalloc bug in xdp_umem_create

WARNING: kmalloc bug in xdp_umem_create

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    7d3bf613e99a Merge tag 'libnvdimm-for-4.18' of git://git.k..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1073f68f800000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f04d8d0a2afb789a
dashboard link: https://syzkaller.appspot.com/bug?extid=4abadc5d69117b346506
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=13c9756f800000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16366f9f800000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+4abadc5d69117b346506@syzkaller.appspotmail.com

random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
WARNING: CPU: 1 PID: 4537 at mm/slab_common.c:996 kmalloc_slab+0x56/0x70  
mm/slab_common.c:996
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 4537 Comm: syz-executor849 Not tainted 4.17.0+ #92
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x1b9/0x294 lib/dump_stack.c:113
  panic+0x22f/0x4de kernel/panic.c:184
  __warn.cold.8+0x163/0x1b3 kernel/panic.c:536
  report_bug+0x252/0x2d0 lib/bug.c:186
  fixup_bug arch/x86/kernel/traps.c:178 [inline]
  do_error_trap+0x1fc/0x4d0 arch/x86/kernel/traps.c:296
  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
  invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992
RIP: 0010:kmalloc_slab+0x56/0x70 mm/slab_common.c:996
Code: c5 c0 ca d0 88 5d c3 b8 10 00 00 00 48 85 ff 74 f4 83 ef 01 c1 ef 03  
0f b6 87 e0 c9 d0 88 eb d8 31 c0 81 e6 00 02 00 00 75 db <0f> 0b 5d c3 48  
8b 04 c5 00 ca d0 88 5d c3 66 90 66 2e 0f 1f 84 00
RSP: 0018:ffff8801acc67998 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff877abea2
RDX: 1ffff10035e17ce3 RSI: 0000000000000000 RDI: 0000000001000010
RBP: ffff8801acc67998 R08: ffff8801d91d82c0 R09: ffffed0035e17cd9
R10: ffffed0035e17cd9 R11: ffff8801af0be6cb R12: dffffc0000000000
R13: 0000000020000000 R14: ffff8801af0be6b0 R15: 00000000006080c0
  __do_kmalloc mm/slab.c:3713 [inline]
  __kmalloc+0x25/0x760 mm/slab.c:3727
  kmalloc_array include/linux/slab.h:634 [inline]
  kcalloc include/linux/slab.h:645 [inline]
  xdp_umem_pin_pages net/xdp/xdp_umem.c:205 [inline]
  xdp_umem_reg net/xdp/xdp_umem.c:318 [inline]
  xdp_umem_create+0x5c9/0x10f0 net/xdp/xdp_umem.c:349
  xsk_setsockopt+0x443/0x550 net/xdp/xsk.c:531
  __sys_setsockopt+0x1bd/0x390 net/socket.c:1935
  __do_sys_setsockopt net/socket.c:1946 [inline]
  __se_sys_setsockopt net/socket.c:1943 [inline]
  __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1943
  do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x43fce9
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 0f 83 6b 45 00 00 c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffedcafaac8 EFLAGS: 00000213 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fce9
RDX: 0000000000000004 RSI: 000000000000011b RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000018 R09: 00000000004002c8
R10: 0000000020000040 R11: 0000000000000213 R12: 0000000000401610
R13: 00000000004016a0 R14: 0000000000000000 R15: 0000000000000000
Dumping ftrace buffer:
    (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with  
syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

Re: WARNING: kmalloc bug in xdp_umem_create

[Tetsuo Handa]

On 2018/06/10 7:47, syzbot wrote:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    7d3bf613e99a Merge tag 'libnvdimm-for-4.18' of git://git.k..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1073f68f800000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=f04d8d0a2afb789a
> dashboard link: https://syzkaller.appspot.com/bug?extid=4abadc5d69117b346506
> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=13c9756f800000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16366f9f800000
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+4abadc5d69117b346506@syzkaller.appspotmail.com
> 
> random: sshd: uninitialized urandom read (32 bytes read)
> random: sshd: uninitialized urandom read (32 bytes read)
> random: sshd: uninitialized urandom read (32 bytes read)
> random: sshd: uninitialized urandom read (32 bytes read)
> random: sshd: uninitialized urandom read (32 bytes read)
> WARNING: CPU: 1 PID: 4537 at mm/slab_common.c:996 kmalloc_slab+0x56/0x70 mm/slab_common.c:996
> Kernel panic - not syncing: panic_on_warn set ...

syzbot gave up upon kmalloc(), but actually error handling path has
NULL pointer dereference bug.

----------
#include <sys/socket.h>
#include <unistd.h>
#define PF_XDP 44
#define SOL_XDP 283
#define XDP_UMEM_REG 4

int main(int argc, char *argv[])
{
	int fd = socket(PF_XDP, SOCK_RAW, 0);
	struct xdp_umem_reg {
		unsigned long long addr;
		unsigned long long len;
		unsigned int chunk_size;
		unsigned int headroom;
	} arg = {
		0x20000000,
		0x200002000,
		0x800,
		2
	};
	setsockopt(fd, SOL_XDP, XDP_UMEM_REG, &arg, sizeof(arg));
	return 0;
}
----------

[   95.172962] WARNING: CPU: 3 PID: 2891 at mm/page_alloc.c:4065 __alloc_pages_nodemask+0x283/0xdf0
[   95.175179] Modules linked in: pcspkr sg vmw_vmci i2c_piix4 sd_mod ata_generic pata_acpi ahci libahci vmwgfx drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm drm ata_piix mptspi scsi_transport_spi i2c_core mptscsih e1000 mptbase libata serio_raw
[   95.180614] CPU: 3 PID: 2891 Comm: a.out Kdump: loaded Not tainted 4.17.0+ #421
[   95.182351] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 05/19/2017
[   95.184909] RIP: 0010:__alloc_pages_nodemask+0x283/0xdf0
[   95.186319] Code: 00 00 04 00 41 0f 44 c6 48 3b 5c 24 78 c6 84 24 90 00 00 00 00 0f 85 50 0b 00 00 41 83 fd 0a 76 1d f6 c4 02 0f 85 3b ff ff ff <0f> 0b e9 34 ff ff ff 0f 0b 0f 1f 40 00 e9 10 fe ff ff 0f 0b 89 c2
[   95.190997] RSP: 0018:ffffc900008efd20 EFLAGS: 00010246
[   95.192257] RAX: 000000000060c0c0 RBX: 0000000000000000 RCX: ffff88013f7fe920
[   95.194005] RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000
[   95.195697] RBP: 000000000060c0c0 R08: 0000000000000001 R09: ffffffffffffef81
[   95.197393] R10: 000000000000000d R11: 0000000000000e8c R12: 0000000000000001
[   95.199084] R13: 000000000000000d R14: 000000000060c0c0 R15: 0000000000000000
[   95.200735] FS:  00007f8387e61740(0000) GS:ffff88013f4c0000(0000) knlGS:0000000000000000
[   95.203441] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   95.205726] CR2: 0000000020000040 CR3: 0000000133e2c006 CR4: 00000000001606e0
[   95.207743] Call Trace:
[   95.208427]  ? __lock_acquire+0x22a/0x1830
[   95.209391]  ? kmalloc_order+0x15/0x60
[   95.210266]  ? __kmalloc+0x20a/0x210
[   95.211104]  ? xdp_umem_create+0x16e/0x3c0
[   95.212095]  ? xsk_setsockopt+0x153/0x1a0
[   95.213143]  ? __sys_setsockopt+0x67/0xb0
[   95.214058]  ? __x64_sys_setsockopt+0x1b/0x20
[   95.215040]  ? do_syscall_64+0x4f/0x1f0
[   95.215890]  ? entry_SYSCALL_64_after_hwframe+0x49/0xbe
[   95.217079] irq event stamp: 5296
[   95.217785] hardirqs last  enabled at (5295): [<ffffffff810b2a77>] __raw_spin_lock_init+0x17/0x50
[   95.220381] hardirqs last disabled at (5296): [<ffffffff81800f33>] error_entry+0x73/0xc0
[   95.222447] softirqs last  enabled at (5284): [<ffffffff81a00183>] __do_softirq+0x183/0x204
[   95.224328] softirqs last disabled at (5277): [<ffffffff81061bcd>] irq_exit+0xcd/0xf0
[   95.226065] ---[ end trace 75b6f67917663997 ]---
[   95.227250] BUG: unable to handle kernel NULL pointer dereference at 0000000000000060
[   95.229101] PGD 1342eb067 P4D 1342eb067 PUD 1314a2067 PMD 0
[   95.230398] Oops: 0002 [#1] SMP DEBUG_PAGEALLOC
[   95.231418] CPU: 3 PID: 2891 Comm: a.out Kdump: loaded Tainted: G        W         4.17.0+ #421
[   95.233474] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 05/19/2017
[   95.236636] RIP: 0010:xdp_umem_create+0x228/0x3c0
[   95.237867] Code: f4 ff ff ff e8 b9 f9 ff ff 48 8b bb 90 00 00 00 e8 3d d9 a7 ff 48 c7 83 90 00 00 00 00 00 00 00 48 8b 43 30 8b 93 98 00 00 00 <f0> 48 29 50 60 48 8b 7b 30 49 63 ec e8 57 10 92 ff 48 8b 7b 38 e8
[   95.241945] RSP: 0018:ffffc900008efe88 EFLAGS: 00010246
[   95.243236] RAX: 0000000000000000 RBX: ffff880133401288 RCX: 000000000060c0c0
[   95.244789] RDX: 0000000000200002 RSI: 0000000001000010 RDI: 0000000000000000
[   95.247382] RBP: 0000000000200002 R08: 0000000000000001 R09: ffffffffffffef81
[   95.249735] R10: 000000000000000d R11: 0000000000000e8c R12: 00000000fffffff4
[   95.252391] R13: 0000000000000040 R14: 0000000020000000 R15: 00000000000007c0
[   95.255280] FS:  00007f8387e61740(0000) GS:ffff88013f4c0000(0000) knlGS:0000000000000000
[   95.257918] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   95.260068] CR2: 0000000000000060 CR3: 0000000133e2c006 CR4: 00000000001606e0
[   95.262535] Call Trace:
[   95.263900]  ? xsk_setsockopt+0x153/0x1a0
[   95.265495]  ? __sys_setsockopt+0x67/0xb0
[   95.267108]  ? __x64_sys_setsockopt+0x1b/0x20
[   95.269532]  ? do_syscall_64+0x4f/0x1f0
[   95.271474]  ? entry_SYSCALL_64_after_hwframe+0x49/0xbe
[   95.273292] Modules linked in: pcspkr sg vmw_vmci i2c_piix4 sd_mod ata_generic pata_acpi ahci libahci vmwgfx drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm drm ata_piix mptspi scsi_transport_spi i2c_core mptscsih e1000 mptbase libata serio_raw
[   95.279548] CR2: 0000000000000060
[   95.281044] ---[ end trace 75b6f67917663998 ]---
[   95.283132] RIP: 0010:xdp_umem_create+0x228/0x3c0
[   95.285257] Code: f4 ff ff ff e8 b9 f9 ff ff 48 8b bb 90 00 00 00 e8 3d d9 a7 ff 48 c7 83 90 00 00 00 00 00 00 00 48 8b 43 30 8b 93 98 00 00 00 <f0> 48 29 50 60 48 8b 7b 30 49 63 ec e8 57 10 92 ff 48 8b 7b 38 e8
[   95.291487] RSP: 0018:ffffc900008efe88 EFLAGS: 00010246
[   95.293429] RAX: 0000000000000000 RBX: ffff880133401288 RCX: 000000000060c0c0
[   95.295761] RDX: 0000000000200002 RSI: 0000000001000010 RDI: 0000000000000000
[   95.298072] RBP: 0000000000200002 R08: 0000000000000001 R09: ffffffffffffef81
[   95.300403] R10: 000000000000000d R11: 0000000000000e8c R12: 00000000fffffff4
[   95.303699] R13: 0000000000000040 R14: 0000000020000000 R15: 00000000000007c0
[   95.306178] FS:  00007f8387e61740(0000) GS:ffff88013f4c0000(0000) knlGS:0000000000000000
[   95.308645] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   95.310782] CR2: 0000000000000060 CR3: 0000000133e2c006 CR4: 00000000001606e0

xdp_umem_create+0x228/0x3c0:
arch_atomic64_sub at arch/x86/include/asm/atomic64_64.h:60
(inlined by) atomic64_sub at include/asm-generic/atomic-instrumented.h:145
(inlined by) atomic_long_sub at include/asm-generic/atomic-long.h:199
(inlined by) xdp_umem_unaccount_pages at net/xdp/xdp_umem.c:135
(inlined by) xdp_umem_reg at net/xdp/xdp_umem.c:334
(inlined by) xdp_umem_create at net/xdp/xdp_umem.c:349

Re: WARNING: kmalloc bug in xdp_umem_create

[Björn Töpel]

Den sön 10 juni 2018 kl 04:53 skrev Tetsuo Handa
<penguin-kernel@i-love.sakura.ne.jp>:
>
> On 2018/06/10 7:47, syzbot wrote:
> > Hello,
> >
> > syzbot found the following crash on:
> >
> > HEAD commit:    7d3bf613e99a Merge tag 'libnvdimm-for-4.18' of git://git.k..
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=1073f68f800000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=f04d8d0a2afb789a
> > dashboard link: https://syzkaller.appspot.com/bug?extid=4abadc5d69117b346506
> > compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> > syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=13c9756f800000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16366f9f800000
> >
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: syzbot+4abadc5d69117b346506@syzkaller.appspotmail.com
> >
> > random: sshd: uninitialized urandom read (32 bytes read)
> > random: sshd: uninitialized urandom read (32 bytes read)
> > random: sshd: uninitialized urandom read (32 bytes read)
> > random: sshd: uninitialized urandom read (32 bytes read)
> > random: sshd: uninitialized urandom read (32 bytes read)
> > WARNING: CPU: 1 PID: 4537 at mm/slab_common.c:996 kmalloc_slab+0x56/0x70 mm/slab_common.c:996
> > Kernel panic - not syncing: panic_on_warn set ...
>
> syzbot gave up upon kmalloc(), but actually error handling path has
> NULL pointer dereference bug.
>

Thanks Tetsuo! This crash has been fixed by Daniel Borkmann in commit
c09290c56376 ("bpf, xdp: fix crash in xdp_umem_unaccount_pages").


Björn


> ----------
> #include <sys/socket.h>
> #include <unistd.h>
> #define PF_XDP 44
> #define SOL_XDP 283
> #define XDP_UMEM_REG 4
>
> int main(int argc, char *argv[])
> {
>         int fd = socket(PF_XDP, SOCK_RAW, 0);
>         struct xdp_umem_reg {
>                 unsigned long long addr;
>                 unsigned long long len;
>                 unsigned int chunk_size;
>                 unsigned int headroom;
>         } arg = {
>                 0x20000000,
>                 0x200002000,
>                 0x800,
>                 2
>         };
>         setsockopt(fd, SOL_XDP, XDP_UMEM_REG, &arg, sizeof(arg));
>         return 0;
> }
> ----------
>
> [   95.172962] WARNING: CPU: 3 PID: 2891 at mm/page_alloc.c:4065 __alloc_pages_nodemask+0x283/0xdf0
> [   95.175179] Modules linked in: pcspkr sg vmw_vmci i2c_piix4 sd_mod ata_generic pata_acpi ahci libahci vmwgfx drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm drm ata_piix mptspi scsi_transport_spi i2c_core mptscsih e1000 mptbase libata serio_raw
> [   95.180614] CPU: 3 PID: 2891 Comm: a.out Kdump: loaded Not tainted 4.17.0+ #421
> [   95.182351] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 05/19/2017
> [   95.184909] RIP: 0010:__alloc_pages_nodemask+0x283/0xdf0
> [   95.186319] Code: 00 00 04 00 41 0f 44 c6 48 3b 5c 24 78 c6 84 24 90 00 00 00 00 0f 85 50 0b 00 00 41 83 fd 0a 76 1d f6 c4 02 0f 85 3b ff ff ff <0f> 0b e9 34 ff ff ff 0f 0b 0f 1f 40 00 e9 10 fe ff ff 0f 0b 89 c2
> [   95.190997] RSP: 0018:ffffc900008efd20 EFLAGS: 00010246
> [   95.192257] RAX: 000000000060c0c0 RBX: 0000000000000000 RCX: ffff88013f7fe920
> [   95.194005] RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000
> [   95.195697] RBP: 000000000060c0c0 R08: 0000000000000001 R09: ffffffffffffef81
> [   95.197393] R10: 000000000000000d R11: 0000000000000e8c R12: 0000000000000001
> [   95.199084] R13: 000000000000000d R14: 000000000060c0c0 R15: 0000000000000000
> [   95.200735] FS:  00007f8387e61740(0000) GS:ffff88013f4c0000(0000) knlGS:0000000000000000
> [   95.203441] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   95.205726] CR2: 0000000020000040 CR3: 0000000133e2c006 CR4: 00000000001606e0
> [   95.207743] Call Trace:
> [   95.208427]  ? __lock_acquire+0x22a/0x1830
> [   95.209391]  ? kmalloc_order+0x15/0x60
> [   95.210266]  ? __kmalloc+0x20a/0x210
> [   95.211104]  ? xdp_umem_create+0x16e/0x3c0
> [   95.212095]  ? xsk_setsockopt+0x153/0x1a0
> [   95.213143]  ? __sys_setsockopt+0x67/0xb0
> [   95.214058]  ? __x64_sys_setsockopt+0x1b/0x20
> [   95.215040]  ? do_syscall_64+0x4f/0x1f0
> [   95.215890]  ? entry_SYSCALL_64_after_hwframe+0x49/0xbe
> [   95.217079] irq event stamp: 5296
> [   95.217785] hardirqs last  enabled at (5295): [<ffffffff810b2a77>] __raw_spin_lock_init+0x17/0x50
> [   95.220381] hardirqs last disabled at (5296): [<ffffffff81800f33>] error_entry+0x73/0xc0
> [   95.222447] softirqs last  enabled at (5284): [<ffffffff81a00183>] __do_softirq+0x183/0x204
> [   95.224328] softirqs last disabled at (5277): [<ffffffff81061bcd>] irq_exit+0xcd/0xf0
> [   95.226065] ---[ end trace 75b6f67917663997 ]---
> [   95.227250] BUG: unable to handle kernel NULL pointer dereference at 0000000000000060
> [   95.229101] PGD 1342eb067 P4D 1342eb067 PUD 1314a2067 PMD 0
> [   95.230398] Oops: 0002 [#1] SMP DEBUG_PAGEALLOC
> [   95.231418] CPU: 3 PID: 2891 Comm: a.out Kdump: loaded Tainted: G        W         4.17.0+ #421
> [   95.233474] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 05/19/2017
> [   95.236636] RIP: 0010:xdp_umem_create+0x228/0x3c0
> [   95.237867] Code: f4 ff ff ff e8 b9 f9 ff ff 48 8b bb 90 00 00 00 e8 3d d9 a7 ff 48 c7 83 90 00 00 00 00 00 00 00 48 8b 43 30 8b 93 98 00 00 00 <f0> 48 29 50 60 48 8b 7b 30 49 63 ec e8 57 10 92 ff 48 8b 7b 38 e8
> [   95.241945] RSP: 0018:ffffc900008efe88 EFLAGS: 00010246
> [   95.243236] RAX: 0000000000000000 RBX: ffff880133401288 RCX: 000000000060c0c0
> [   95.244789] RDX: 0000000000200002 RSI: 0000000001000010 RDI: 0000000000000000
> [   95.247382] RBP: 0000000000200002 R08: 0000000000000001 R09: ffffffffffffef81
> [   95.249735] R10: 000000000000000d R11: 0000000000000e8c R12: 00000000fffffff4
> [   95.252391] R13: 0000000000000040 R14: 0000000020000000 R15: 00000000000007c0
> [   95.255280] FS:  00007f8387e61740(0000) GS:ffff88013f4c0000(0000) knlGS:0000000000000000
> [   95.257918] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   95.260068] CR2: 0000000000000060 CR3: 0000000133e2c006 CR4: 00000000001606e0
> [   95.262535] Call Trace:
> [   95.263900]  ? xsk_setsockopt+0x153/0x1a0
> [   95.265495]  ? __sys_setsockopt+0x67/0xb0
> [   95.267108]  ? __x64_sys_setsockopt+0x1b/0x20
> [   95.269532]  ? do_syscall_64+0x4f/0x1f0
> [   95.271474]  ? entry_SYSCALL_64_after_hwframe+0x49/0xbe
> [   95.273292] Modules linked in: pcspkr sg vmw_vmci i2c_piix4 sd_mod ata_generic pata_acpi ahci libahci vmwgfx drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm drm ata_piix mptspi scsi_transport_spi i2c_core mptscsih e1000 mptbase libata serio_raw
> [   95.279548] CR2: 0000000000000060
> [   95.281044] ---[ end trace 75b6f67917663998 ]---
> [   95.283132] RIP: 0010:xdp_umem_create+0x228/0x3c0
> [   95.285257] Code: f4 ff ff ff e8 b9 f9 ff ff 48 8b bb 90 00 00 00 e8 3d d9 a7 ff 48 c7 83 90 00 00 00 00 00 00 00 48 8b 43 30 8b 93 98 00 00 00 <f0> 48 29 50 60 48 8b 7b 30 49 63 ec e8 57 10 92 ff 48 8b 7b 38 e8
> [   95.291487] RSP: 0018:ffffc900008efe88 EFLAGS: 00010246
> [   95.293429] RAX: 0000000000000000 RBX: ffff880133401288 RCX: 000000000060c0c0
> [   95.295761] RDX: 0000000000200002 RSI: 0000000001000010 RDI: 0000000000000000
> [   95.298072] RBP: 0000000000200002 R08: 0000000000000001 R09: ffffffffffffef81
> [   95.300403] R10: 000000000000000d R11: 0000000000000e8c R12: 00000000fffffff4
> [   95.303699] R13: 0000000000000040 R14: 0000000020000000 R15: 00000000000007c0
> [   95.306178] FS:  00007f8387e61740(0000) GS:ffff88013f4c0000(0000) knlGS:0000000000000000
> [   95.308645] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   95.310782] CR2: 0000000000000060 CR3: 0000000133e2c006 CR4: 00000000001606e0
>
> xdp_umem_create+0x228/0x3c0:
> arch_atomic64_sub at arch/x86/include/asm/atomic64_64.h:60
> (inlined by) atomic64_sub at include/asm-generic/atomic-instrumented.h:145
> (inlined by) atomic_long_sub at include/asm-generic/atomic-long.h:199
> (inlined by) xdp_umem_unaccount_pages at net/xdp/xdp_umem.c:135
> (inlined by) xdp_umem_reg at net/xdp/xdp_umem.c:334
> (inlined by) xdp_umem_create at net/xdp/xdp_umem.c:349

Re: WARNING: kmalloc bug in xdp_umem_create

[Dmitry Vyukov]

On Sun, Jun 10, 2018 at 11:31 AM, Björn Töpel <bjorn.topel@gmail.com> wrote:
> Den sön 10 juni 2018 kl 04:53 skrev Tetsuo Handa
> <penguin-kernel@i-love.sakura.ne.jp>:
>>
>> On 2018/06/10 7:47, syzbot wrote:
>> > Hello,
>> >
>> > syzbot found the following crash on:
>> >
>> > HEAD commit:    7d3bf613e99a Merge tag 'libnvdimm-for-4.18' of git://git.k..
>> > git tree:       upstream
>> > console output: https://syzkaller.appspot.com/x/log.txt?x=1073f68f800000
>> > kernel config:  https://syzkaller.appspot.com/x/.config?x=f04d8d0a2afb789a
>> > dashboard link: https://syzkaller.appspot.com/bug?extid=4abadc5d69117b346506
>> > compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
>> > syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=13c9756f800000
>> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16366f9f800000
>> >
>> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> > Reported-by: syzbot+4abadc5d69117b346506@syzkaller.appspotmail.com
>> >
>> > random: sshd: uninitialized urandom read (32 bytes read)
>> > random: sshd: uninitialized urandom read (32 bytes read)
>> > random: sshd: uninitialized urandom read (32 bytes read)
>> > random: sshd: uninitialized urandom read (32 bytes read)
>> > random: sshd: uninitialized urandom read (32 bytes read)
>> > WARNING: CPU: 1 PID: 4537 at mm/slab_common.c:996 kmalloc_slab+0x56/0x70 mm/slab_common.c:996
>> > Kernel panic - not syncing: panic_on_warn set ...
>>
>> syzbot gave up upon kmalloc(), but actually error handling path has
>> NULL pointer dereference bug.
>>
>
> Thanks Tetsuo! This crash has been fixed by Daniel Borkmann in commit
> c09290c56376 ("bpf, xdp: fix crash in xdp_umem_unaccount_pages").

Let's tell syzbot about this:

#syz fix: bpf, xdp: fix crash in xdp_umem_unaccount_pages

Re: WARNING: kmalloc bug in xdp_umem_create

[Tetsuo Handa]

On 2018/06/10 20:52, Dmitry Vyukov wrote:
> On Sun, Jun 10, 2018 at 11:31 AM, Björn Töpel <bjorn.topel@gmail.com> wrote:
>> Den sön 10 juni 2018 kl 04:53 skrev Tetsuo Handa
>> <penguin-kernel@i-love.sakura.ne.jp>:
>>>
>>> On 2018/06/10 7:47, syzbot wrote:
>>>> Hello,
>>>>
>>>> syzbot found the following crash on:
>>>>
>>>> HEAD commit:    7d3bf613e99a Merge tag 'libnvdimm-for-4.18' of git://git.k..
>>>> git tree:       upstream
>>>> console output: https://syzkaller.appspot.com/x/log.txt?x=1073f68f800000
>>>> kernel config:  https://syzkaller.appspot.com/x/.config?x=f04d8d0a2afb789a
>>>> dashboard link: https://syzkaller.appspot.com/bug?extid=4abadc5d69117b346506
>>>> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
>>>> syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=13c9756f800000
>>>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16366f9f800000
>>>>
>>>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>>>> Reported-by: syzbot+4abadc5d69117b346506@syzkaller.appspotmail.com
>>>>
>>>> random: sshd: uninitialized urandom read (32 bytes read)
>>>> random: sshd: uninitialized urandom read (32 bytes read)
>>>> random: sshd: uninitialized urandom read (32 bytes read)
>>>> random: sshd: uninitialized urandom read (32 bytes read)
>>>> random: sshd: uninitialized urandom read (32 bytes read)
>>>> WARNING: CPU: 1 PID: 4537 at mm/slab_common.c:996 kmalloc_slab+0x56/0x70 mm/slab_common.c:996
>>>> Kernel panic - not syncing: panic_on_warn set ...
>>>
>>> syzbot gave up upon kmalloc(), but actually error handling path has
>>> NULL pointer dereference bug.
>>>
>>
>> Thanks Tetsuo! This crash has been fixed by Daniel Borkmann in commit
>> c09290c56376 ("bpf, xdp: fix crash in xdp_umem_unaccount_pages").
> 
> Let's tell syzbot about this:
> 
> #syz fix: bpf, xdp: fix crash in xdp_umem_unaccount_pages
> 
> 
Excuse me, but that patch fixes NULL pointer dereference which occurs after kmalloc()'s
"WARNING: CPU: 1 PID: 4537 at mm/slab_common.c:996 kmalloc_slab+0x56/0x70 mm/slab_common.c:996"
message. That is, "Too large memory allocation" itself is not yet fixed.

Re: WARNING: kmalloc bug in xdp_umem_create

[Dmitry Vyukov]

On Sun, Jun 10, 2018 at 2:53 PM, Tetsuo Handa
<penguin-kernel@i-love.sakura.ne.jp> wrote:
> On 2018/06/10 20:52, Dmitry Vyukov wrote:
>> On Sun, Jun 10, 2018 at 11:31 AM, Björn Töpel <bjorn.topel@gmail.com> wrote:
>>> Den sön 10 juni 2018 kl 04:53 skrev Tetsuo Handa
>>> <penguin-kernel@i-love.sakura.ne.jp>:
>>>>
>>>> On 2018/06/10 7:47, syzbot wrote:
>>>>> Hello,
>>>>>
>>>>> syzbot found the following crash on:
>>>>>
>>>>> HEAD commit:    7d3bf613e99a Merge tag 'libnvdimm-for-4.18' of git://git.k..
>>>>> git tree:       upstream
>>>>> console output: https://syzkaller.appspot.com/x/log.txt?x=1073f68f800000
>>>>> kernel config:  https://syzkaller.appspot.com/x/.config?x=f04d8d0a2afb789a
>>>>> dashboard link: https://syzkaller.appspot.com/bug?extid=4abadc5d69117b346506
>>>>> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
>>>>> syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=13c9756f800000
>>>>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16366f9f800000
>>>>>
>>>>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>>>>> Reported-by: syzbot+4abadc5d69117b346506@syzkaller.appspotmail.com
>>>>>
>>>>> random: sshd: uninitialized urandom read (32 bytes read)
>>>>> random: sshd: uninitialized urandom read (32 bytes read)
>>>>> random: sshd: uninitialized urandom read (32 bytes read)
>>>>> random: sshd: uninitialized urandom read (32 bytes read)
>>>>> random: sshd: uninitialized urandom read (32 bytes read)
>>>>> WARNING: CPU: 1 PID: 4537 at mm/slab_common.c:996 kmalloc_slab+0x56/0x70 mm/slab_common.c:996
>>>>> Kernel panic - not syncing: panic_on_warn set ...
>>>>
>>>> syzbot gave up upon kmalloc(), but actually error handling path has
>>>> NULL pointer dereference bug.
>>>>
>>>
>>> Thanks Tetsuo! This crash has been fixed by Daniel Borkmann in commit
>>> c09290c56376 ("bpf, xdp: fix crash in xdp_umem_unaccount_pages").
>>
>> Let's tell syzbot about this:
>>
>> #syz fix: bpf, xdp: fix crash in xdp_umem_unaccount_pages
>>
>>
> Excuse me, but that patch fixes NULL pointer dereference which occurs after kmalloc()'s
> "WARNING: CPU: 1 PID: 4537 at mm/slab_common.c:996 kmalloc_slab+0x56/0x70 mm/slab_common.c:996"
> message. That is, "Too large memory allocation" itself is not yet fixed.

You are right! I fixed it up. Thanks

Re: WARNING: kmalloc bug in xdp_umem_create

[Björn Töpel]

Den sön 10 juni 2018 kl 14:53 skrev Tetsuo Handa
<penguin-kernel@i-love.sakura.ne.jp>:
>
> On 2018/06/10 20:52, Dmitry Vyukov wrote:
> > On Sun, Jun 10, 2018 at 11:31 AM, Björn Töpel <bjorn.topel@gmail.com> wrote:
> >> Den sön 10 juni 2018 kl 04:53 skrev Tetsuo Handa
> >> <penguin-kernel@i-love.sakura.ne.jp>:
> >>>
> >>> On 2018/06/10 7:47, syzbot wrote:
> >>>> Hello,
> >>>>
> >>>> syzbot found the following crash on:
> >>>>
> >>>> HEAD commit:    7d3bf613e99a Merge tag 'libnvdimm-for-4.18' of git://git.k..
> >>>> git tree:       upstream
> >>>> console output: https://syzkaller.appspot.com/x/log.txt?x=1073f68f800000
> >>>> kernel config:  https://syzkaller.appspot.com/x/.config?x=f04d8d0a2afb789a
> >>>> dashboard link: https://syzkaller.appspot.com/bug?extid=4abadc5d69117b346506
> >>>> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> >>>> syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=13c9756f800000
> >>>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16366f9f800000
> >>>>
> >>>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> >>>> Reported-by: syzbot+4abadc5d69117b346506@syzkaller.appspotmail.com
> >>>>
> >>>> random: sshd: uninitialized urandom read (32 bytes read)
> >>>> random: sshd: uninitialized urandom read (32 bytes read)
> >>>> random: sshd: uninitialized urandom read (32 bytes read)
> >>>> random: sshd: uninitialized urandom read (32 bytes read)
> >>>> random: sshd: uninitialized urandom read (32 bytes read)
> >>>> WARNING: CPU: 1 PID: 4537 at mm/slab_common.c:996 kmalloc_slab+0x56/0x70 mm/slab_common.c:996
> >>>> Kernel panic - not syncing: panic_on_warn set ...
> >>>
> >>> syzbot gave up upon kmalloc(), but actually error handling path has
> >>> NULL pointer dereference bug.
> >>>
> >>
> >> Thanks Tetsuo! This crash has been fixed by Daniel Borkmann in commit
> >> c09290c56376 ("bpf, xdp: fix crash in xdp_umem_unaccount_pages").
> >
> > Let's tell syzbot about this:
> >
> > #syz fix: bpf, xdp: fix crash in xdp_umem_unaccount_pages
> >
> >
> Excuse me, but that patch fixes NULL pointer dereference which occurs after kmalloc()'s
> "WARNING: CPU: 1 PID: 4537 at mm/slab_common.c:996 kmalloc_slab+0x56/0x70 mm/slab_common.c:996"
> message. That is, "Too large memory allocation" itself is not yet fixed.

The code relies on that the sl{u,a,o}b layer says no, and the
setsockopt bails out. The warning could be opted out using
__GFP_NOWARN. Is there another preferred way? Two get_user_pages
calls, where the first call would set pages to NULL just to fault the
region? Walk the process' VMAs? Something else?


Björn

Re: WARNING: kmalloc bug in xdp_umem_create

[Dmitry Vyukov]

On Sun, Jun 10, 2018 at 3:03 PM, Björn Töpel <bjorn.topel@gmail.com> wrote:
>> On 2018/06/10 20:52, Dmitry Vyukov wrote:
>> > On Sun, Jun 10, 2018 at 11:31 AM, Björn Töpel <bjorn.topel@gmail.com> wrote:
>> >> Den sön 10 juni 2018 kl 04:53 skrev Tetsuo Handa
>> >> <penguin-kernel@i-love.sakura.ne.jp>:
>> >>>
>> >>> On 2018/06/10 7:47, syzbot wrote:
>> >>>> Hello,
>> >>>>
>> >>>> syzbot found the following crash on:
>> >>>>
>> >>>> HEAD commit:    7d3bf613e99a Merge tag 'libnvdimm-for-4.18' of git://git.k..
>> >>>> git tree:       upstream
>> >>>> console output: https://syzkaller.appspot.com/x/log.txt?x=1073f68f800000
>> >>>> kernel config:  https://syzkaller.appspot.com/x/.config?x=f04d8d0a2afb789a
>> >>>> dashboard link: https://syzkaller.appspot.com/bug?extid=4abadc5d69117b346506
>> >>>> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
>> >>>> syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=13c9756f800000
>> >>>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16366f9f800000
>> >>>>
>> >>>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> >>>> Reported-by: syzbot+4abadc5d69117b346506@syzkaller.appspotmail.com
>> >>>>
>> >>>> random: sshd: uninitialized urandom read (32 bytes read)
>> >>>> random: sshd: uninitialized urandom read (32 bytes read)
>> >>>> random: sshd: uninitialized urandom read (32 bytes read)
>> >>>> random: sshd: uninitialized urandom read (32 bytes read)
>> >>>> random: sshd: uninitialized urandom read (32 bytes read)
>> >>>> WARNING: CPU: 1 PID: 4537 at mm/slab_common.c:996 kmalloc_slab+0x56/0x70 mm/slab_common.c:996
>> >>>> Kernel panic - not syncing: panic_on_warn set ...
>> >>>
>> >>> syzbot gave up upon kmalloc(), but actually error handling path has
>> >>> NULL pointer dereference bug.
>> >>>
>> >>
>> >> Thanks Tetsuo! This crash has been fixed by Daniel Borkmann in commit
>> >> c09290c56376 ("bpf, xdp: fix crash in xdp_umem_unaccount_pages").
>> >
>> > Let's tell syzbot about this:
>> >
>> > #syz fix: bpf, xdp: fix crash in xdp_umem_unaccount_pages
>> >
>> >
>> Excuse me, but that patch fixes NULL pointer dereference which occurs after kmalloc()'s
>> "WARNING: CPU: 1 PID: 4537 at mm/slab_common.c:996 kmalloc_slab+0x56/0x70 mm/slab_common.c:996"
>> message. That is, "Too large memory allocation" itself is not yet fixed.
>
> The code relies on that the sl{u,a,o}b layer says no, and the
> setsockopt bails out. The warning could be opted out using
> __GFP_NOWARN. Is there another preferred way? Two get_user_pages
> calls, where the first call would set pages to NULL just to fault the
> region? Walk the process' VMAs? Something else?

Hi Björn,

Yes, either __GFP_NOWARN for allocations with user-controllable size
or stricter custom limit (if we don't want current sla/u/ob
implementation details to be part of public kernel interface).

Re: WARNING: kmalloc bug in xdp_umem_create

[Daniel Borkmann]

On 06/10/2018 03:03 PM, Björn Töpel wrote:
> Den sön 10 juni 2018 kl 14:53 skrev Tetsuo Handa
> <penguin-kernel@i-love.sakura.ne.jp>:
>> On 2018/06/10 20:52, Dmitry Vyukov wrote:
>>> On Sun, Jun 10, 2018 at 11:31 AM, Björn Töpel <bjorn.topel@gmail.com> wrote:
>>>> Den sön 10 juni 2018 kl 04:53 skrev Tetsuo Handa
>>>> <penguin-kernel@i-love.sakura.ne.jp>:
>>>>> On 2018/06/10 7:47, syzbot wrote:
>>>>>> Hello,
>>>>>>
>>>>>> syzbot found the following crash on:
>>>>>>
>>>>>> HEAD commit:    7d3bf613e99a Merge tag 'libnvdimm-for-4.18' of git://git.k..
>>>>>> git tree:       upstream
>>>>>> console output: https://syzkaller.appspot.com/x/log.txt?x=1073f68f800000
>>>>>> kernel config:  https://syzkaller.appspot.com/x/.config?x=f04d8d0a2afb789a
>>>>>> dashboard link: https://syzkaller.appspot.com/bug?extid=4abadc5d69117b346506
>>>>>> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
>>>>>> syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=13c9756f800000
>>>>>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16366f9f800000
>>>>>>
>>>>>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>>>>>> Reported-by: syzbot+4abadc5d69117b346506@syzkaller.appspotmail.com
>>>>>>
>>>>>> random: sshd: uninitialized urandom read (32 bytes read)
>>>>>> random: sshd: uninitialized urandom read (32 bytes read)
>>>>>> random: sshd: uninitialized urandom read (32 bytes read)
>>>>>> random: sshd: uninitialized urandom read (32 bytes read)
>>>>>> random: sshd: uninitialized urandom read (32 bytes read)
>>>>>> WARNING: CPU: 1 PID: 4537 at mm/slab_common.c:996 kmalloc_slab+0x56/0x70 mm/slab_common.c:996
>>>>>> Kernel panic - not syncing: panic_on_warn set ...
>>>>>
>>>>> syzbot gave up upon kmalloc(), but actually error handling path has
>>>>> NULL pointer dereference bug.
>>>>
>>>> Thanks Tetsuo! This crash has been fixed by Daniel Borkmann in commit
>>>> c09290c56376 ("bpf, xdp: fix crash in xdp_umem_unaccount_pages").
>>>
>>> Let's tell syzbot about this:
>>>
>>> #syz fix: bpf, xdp: fix crash in xdp_umem_unaccount_pages
>>>
>> Excuse me, but that patch fixes NULL pointer dereference which occurs after kmalloc()'s
>> "WARNING: CPU: 1 PID: 4537 at mm/slab_common.c:996 kmalloc_slab+0x56/0x70 mm/slab_common.c:996"
>> message. That is, "Too large memory allocation" itself is not yet fixed.
> 
> The code relies on that the sl{u,a,o}b layer says no, and the
> setsockopt bails out. The warning could be opted out using
> __GFP_NOWARN. Is there another preferred way? Two get_user_pages
> calls, where the first call would set pages to NULL just to fault the
> region? Walk the process' VMAs? Something else?

(Now resolved as well.)

#syz fix: xsk: silence warning on memory allocation failure