Hello,
syzbot found the following issue on:
HEAD commit: 9ae1fbdeabd3 Add linux-next specific files for 20211025
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1331363cb00000
kernel config: https://syzkaller.appspot.com/x/.config?x=aeb17e42bc109064
dashboard link: https://syzkaller.appspot.com/bug?extid=b86736b5935e0d25b446
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=116ce954b00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=132fcf62b00000
The issue was bisected to:
commit 22849b5ea5952d853547cc5e0651f34a246b2a4f
Author: Leon Romanovsky [off-list ref]
Date: Thu Oct 21 14:16:14 2021 +0000
devlink: Remove not-executed trap policer notifications
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=137d8bfcb00000
final oops: https://syzkaller.appspot.com/x/report.txt?x=10fd8bfcb00000
console output: https://syzkaller.appspot.com/x/log.txt?x=177d8bfcb00000
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b86736b5935e0d25b446@syzkaller.appspotmail.com
Fixes: 22849b5ea595 ("devlink: Remove not-executed trap policer notifications")
==================================================================
BUG: KASAN: slab-out-of-bounds in memcpy include/linux/fortify-string.h:225 [inline]
BUG: KASAN: slab-out-of-bounds in copy_data+0xf3/0x2e0 drivers/char/hw_random/virtio-rng.c:68
Read of size 64 at addr ffff88801a7a1580 by task syz-executor989/6542
CPU: 1 PID: 6542 Comm: syz-executor989 Not tainted 5.15.0-rc6-next-20211025-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description.constprop.0.cold+0x8d/0x320 mm/kasan/report.c:247
__kasan_report mm/kasan/report.c:433 [inline]
kasan_report.cold+0x83/0xdf mm/kasan/report.c:450
check_region_inline mm/kasan/generic.c:183 [inline]
kasan_check_range+0x13d/0x180 mm/kasan/generic.c:189
memcpy+0x20/0x60 mm/kasan/shadow.c:65
memcpy include/linux/fortify-string.h:225 [inline]
copy_data+0xf3/0x2e0 drivers/char/hw_random/virtio-rng.c:68
virtio_read+0x1e0/0x230 drivers/char/hw_random/virtio-rng.c:90
rng_get_data drivers/char/hw_random/core.c:192 [inline]
rng_dev_read+0x400/0x660 drivers/char/hw_random/core.c:229
vfs_read+0x1b5/0x600 fs/read_write.c:483
ksys_read+0x12d/0x250 fs/read_write.c:623
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f05696617e9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 14 00 00 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 73 01 c3 48 c7 c1 c4 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd06461948 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 000000000001294d RCX: 00007f05696617e9
RDX: 00000000fffffff1 RSI: 0000000020000180 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007ffd064619b0 R09: 00007ffd064619b0
R10: 00007ffd064613d0 R11: 0000000000000246 R12: 00007ffd0646197c
R13: 00007ffd064619b0 R14: 00007ffd06461990 R15: 0000000000000002
</TASK>
Allocated by task 1:
kasan_save_stack+0x1e/0x50 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:434 [inline]
____kasan_kmalloc mm/kasan/common.c:513 [inline]
____kasan_kmalloc mm/kasan/common.c:472 [inline]
__kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:522
kmalloc include/linux/slab.h:590 [inline]
kzalloc include/linux/slab.h:724 [inline]
probe_common+0xaa/0x5b0 drivers/char/hw_random/virtio-rng.c:132
virtio_dev_probe+0x44e/0x760 drivers/virtio/virtio.c:273
call_driver_probe drivers/base/dd.c:517 [inline]
really_probe+0x245/0xcc0 drivers/base/dd.c:596
__driver_probe_device+0x338/0x4d0 drivers/base/dd.c:751
driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:781
__driver_attach+0x22d/0x4e0 drivers/base/dd.c:1140
bus_for_each_dev+0x147/0x1d0 drivers/base/bus.c:301
bus_add_driver+0x41d/0x630 drivers/base/bus.c:618
driver_register+0x220/0x3a0 drivers/base/driver.c:171
do_one_initcall+0x103/0x650 init/main.c:1303
do_initcall_level init/main.c:1378 [inline]
do_initcalls init/main.c:1394 [inline]
do_basic_setup init/main.c:1413 [inline]
kernel_init_freeable+0x6b1/0x73a init/main.c:1618
kernel_init+0x1a/0x1d0 init/main.c:1507
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
The buggy address belongs to the object at ffff88801a7a1400
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 384 bytes inside of
512-byte region [ffff88801a7a1400, ffff88801a7a1600)
The buggy address belongs to the page:
page:ffffea000069e800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1a7a0
head:ffffea000069e800 order:2 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888010c41c80
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, ts 7709676886, free_ts 0
prep_new_page mm/page_alloc.c:2418 [inline]
get_page_from_freelist+0xa72/0x2f50 mm/page_alloc.c:4149
__alloc_pages+0x1b2/0x500 mm/page_alloc.c:5369
alloc_page_interleave+0x1e/0x200 mm/mempolicy.c:2036
alloc_pages+0x29f/0x300 mm/mempolicy.c:2186
alloc_slab_page mm/slub.c:1793 [inline]
allocate_slab mm/slub.c:1930 [inline]
new_slab+0x32d/0x4a0 mm/slub.c:1993
___slab_alloc+0x918/0xfe0 mm/slub.c:3022
__slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3109
slab_alloc_node mm/slub.c:3200 [inline]
slab_alloc mm/slub.c:3242 [inline]
kmem_cache_alloc_trace+0x289/0x2c0 mm/slub.c:3259
kmalloc include/linux/slab.h:590 [inline]
kzalloc include/linux/slab.h:724 [inline]
device_private_init drivers/base/core.c:3238 [inline]
device_add+0x11a7/0x1ee0 drivers/base/core.c:3288
device_create_groups_vargs+0x203/0x280 drivers/base/core.c:4052
device_create_with_groups+0xe3/0x120 drivers/base/core.c:4138
misc_register+0x20a/0x690 drivers/char/misc.c:206
register_miscdev drivers/char/hw_random/core.c:422 [inline]
hwrng_modinit+0xd0/0x109 drivers/char/hw_random/core.c:621
do_one_initcall+0x103/0x650 init/main.c:1303
do_initcall_level init/main.c:1378 [inline]
do_initcalls init/main.c:1394 [inline]
do_basic_setup init/main.c:1413 [inline]
kernel_init_freeable+0x6b1/0x73a init/main.c:1618
kernel_init+0x1a/0x1d0 init/main.c:1507
page_owner free stack trace missing
Memory state around the buggy address:
ffff88801a7a1480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88801a7a1500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88801a7a1580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff88801a7a1600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88801a7a1680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
---
This report 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 issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches
ffff88801a7a1580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff88801a7a1600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88801a7a1680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
---
This report 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 issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches
More likely this came with
caaf2874ba27b92bca6f0298bf88bad94067ec37 hwrng: virtio - don't waste entropy
I'm going to have a look.
Thanks,
Laurent
How bad is it if we just drop this and waste some bytes of entropy?
I don't think it's bad at all. In most of the cases we should use the full buffer.
So, you can drop, I will re-submit them later with a fix.
Thanks,
Laurent
I'm not able to reproduce the problem with next-20211026 and the C reproducer.
And reviewing the code in copy_data() I don't see any issue.
Is it possible to know what it the VM configuration used to test it?
Thanks,
Laurent
I'm not able to reproduce the problem with next-20211026 and the C reproducer.
And reviewing the code in copy_data() I don't see any issue.
Is it possible to know what it the VM configuration used to test it?
Hi Laurent,
syzbot used e2-standard-2 GCE VM when that happened.
You can see some info about these VMs under the "VM info" link on the dashboard.
I'm not able to reproduce the problem with next-20211026 and the C reproducer.
And reviewing the code in copy_data() I don't see any issue.
Is it possible to know what it the VM configuration used to test it?
Hi Laurent,
syzbot used e2-standard-2 GCE VM when that happened.
You can see some info about these VMs under the "VM info" link on the dashboard.
Could you pls confirm whether reverting
caaf2874ba27b92bca6f0298bf88bad94067ec37 addresses this?
I'm not able to reproduce the problem with next-20211026 and the C reproducer.
And reviewing the code in copy_data() I don't see any issue.
Is it possible to know what it the VM configuration used to test it?
Hi Laurent,
syzbot used e2-standard-2 GCE VM when that happened.
You can see some info about these VMs under the "VM info" link on the dashboard.
Could you pls confirm whether reverting
caaf2874ba27b92bca6f0298bf88bad94067ec37 addresses this?
I've restarted the syzbot on top of "hwrng: virtio - don't wait on cleanup" [1] and the
problem has not been triggered.
See https://syzkaller.appspot.com/bug?extid=b86736b5935e0d25b446
Thanks,
Laurent
[1]
d721abbeb145 hwrng: virtio - don't wait on cleanup
bb768beb0a5f hwrng: virtio - add an internal buffer
d25f27432f80 (origin/master, origin/HEAD, master) Merge tag 'arm-soc-fixes-5.15-3' of
git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc
I'm not able to reproduce the problem with next-20211026 and the C reproducer.
And reviewing the code in copy_data() I don't see any issue.
Is it possible to know what it the VM configuration used to test it?
Hi Laurent,
syzbot used e2-standard-2 GCE VM when that happened.
You can see some info about these VMs under the "VM info" link on the dashboard.
Could you pls confirm whether reverting
caaf2874ba27b92bca6f0298bf88bad94067ec37 addresses this?
The problem seems to be introduced by the last patch:
"hwrng: virtio - always add a pending request"
not
"hwrng: virtio - don't waste entropy"
Thanks,
Laurent
Thanks,
Laurent
[1]
d721abbeb145 hwrng: virtio - don't wait on cleanup
bb768beb0a5f hwrng: virtio - add an internal buffer
d25f27432f80 (origin/master, origin/HEAD, master) Merge tag 'arm-soc-fixes-5.15-3' of
git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc
I'm not able to reproduce the problem with next-20211026 and the C reproducer.
And reviewing the code in copy_data() I don't see any issue.
Is it possible to know what it the VM configuration used to test it?
Hi Laurent,
syzbot used e2-standard-2 GCE VM when that happened.
You can see some info about these VMs under the "VM info" link on the dashboard.
Could you pls confirm whether reverting
caaf2874ba27b92bca6f0298bf88bad94067ec37 addresses this?
The problem seems to be introduced by the last patch:
"hwrng: virtio - always add a pending request"
I think I understand the problem.
As we check data_avail != 0 before waiting on the completion, we can have a data_idx != 0.
The following change fixes the problem for me:
I'm not able to reproduce the problem with next-20211026 and the C reproducer.
And reviewing the code in copy_data() I don't see any issue.
Is it possible to know what it the VM configuration used to test it?
Hi Laurent,
syzbot used e2-standard-2 GCE VM when that happened.
You can see some info about these VMs under the "VM info" link on the dashboard.
Could you pls confirm whether reverting
caaf2874ba27b92bca6f0298bf88bad94067ec37 addresses this?
The problem seems to be introduced by the last patch:
"hwrng: virtio - always add a pending request"
I think I understand the problem.
As we check data_avail != 0 before waiting on the completion, we can have a data_idx != 0.
The following change fixes the problem for me: