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SubjectRe: KASAN: slab-out-of-bounds Read in hidraw_ioctl
From
Hello,

syzbot has tested the proposed patch but the reproducer still triggered
crash:
KASAN: slab-out-of-bounds Read in hidraw_ioctl

==================================================================
BUG: KASAN: slab-out-of-bounds in strlen+0x79/0x90 lib/string.c:525
Read of size 1 at addr ffff8881d619df38 by task syz-executor.5/2984

CPU: 0 PID: 2984 Comm: syz-executor.5 Not tainted 5.3.0-rc2+ #1
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+0xca/0x13e lib/dump_stack.c:113
print_address_description+0x6a/0x32c mm/kasan/report.c:351
__kasan_report.cold+0x1a/0x33 mm/kasan/report.c:482
kasan_report+0xe/0x12 mm/kasan/common.c:612
strlen+0x79/0x90 lib/string.c:525
strlen include/linux/string.h:281 [inline]
hidraw_ioctl+0x245/0xae0 drivers/hid/hidraw.c:446
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:509 [inline]
do_vfs_ioctl+0xd2d/0x1330 fs/ioctl.c:696
ksys_ioctl+0x9b/0xc0 fs/ioctl.c:713
__do_sys_ioctl fs/ioctl.c:720 [inline]
__se_sys_ioctl fs/ioctl.c:718 [inline]
__x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:718
do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459829
Code: fd 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f19881acc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459829
RDX: 0000000000000000 RSI: 0000000080404805 RDI: 0000000000000004
RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f19881ad6d4
R13: 00000000004c21de R14: 00000000004d5620 R15: 00000000ffffffff

Allocated by task 1607:
save_stack+0x1b/0x80 mm/kasan/common.c:69
set_track mm/kasan/common.c:77 [inline]
__kasan_kmalloc mm/kasan/common.c:487 [inline]
__kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:460
kmalloc include/linux/slab.h:552 [inline]
syslog_print kernel/printk/printk.c:1346 [inline]
do_syslog kernel/printk/printk.c:1519 [inline]
do_syslog+0x540/0x1380 kernel/printk/printk.c:1493
kmsg_read+0x8a/0xb0 fs/proc/kmsg.c:40
proc_reg_read+0x1c1/0x280 fs/proc/inode.c:223
__vfs_read+0x76/0x100 fs/read_write.c:425
vfs_read+0x1ea/0x430 fs/read_write.c:461
ksys_read+0x127/0x250 fs/read_write.c:587
do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 1607:
save_stack+0x1b/0x80 mm/kasan/common.c:69
set_track mm/kasan/common.c:77 [inline]
__kasan_slab_free+0x130/0x180 mm/kasan/common.c:449
slab_free_hook mm/slub.c:1423 [inline]
slab_free_freelist_hook mm/slub.c:1470 [inline]
slab_free mm/slub.c:3012 [inline]
kfree+0xe4/0x2f0 mm/slub.c:3953
syslog_print kernel/printk/printk.c:1405 [inline]
do_syslog kernel/printk/printk.c:1519 [inline]
do_syslog+0x1098/0x1380 kernel/printk/printk.c:1493
kmsg_read+0x8a/0xb0 fs/proc/kmsg.c:40
proc_reg_read+0x1c1/0x280 fs/proc/inode.c:223
__vfs_read+0x76/0x100 fs/read_write.c:425
vfs_read+0x1ea/0x430 fs/read_write.c:461
ksys_read+0x127/0x250 fs/read_write.c:587
do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8881d619db00
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 56 bytes to the right of
1024-byte region [ffff8881d619db00, ffff8881d619df00)
The buggy address belongs to the page:
page:ffffea0007586700 refcount:1 mapcount:0 mapping:ffff8881da002280
index:0x0 compound_mapcount: 0
flags: 0x200000000010200(slab|head)
raw: 0200000000010200 dead000000000100 dead000000000122 ffff8881da002280
raw: 0000000000000000 00000000000e000e 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8881d619de00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881d619de80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8881d619df00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff8881d619df80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881d619e000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


Tested on:

commit: e96407b4 usb-fuzzer: main usb gadget fuzzer driver
git tree: https://github.com/google/kasan.git
console output: https://syzkaller.appspot.com/x/log.txt?x=1138542e600000
kernel config: https://syzkaller.appspot.com/x/.config?x=cfa2c18fb6a8068e
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
patch: https://syzkaller.appspot.com/x/patch.diff?x=1197b996600000

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