| Description: | In the Linux kernel, the following vulnerability has been resolved:
tracing/timerlat: Move hrtimer_init to timerlat_fd open() Currently,
the timerlat's hrtimer is initialized at the first read of
timerlat_fd, and destroyed at close(). It works, but it causes an
error if the user program open() and close() the file without reading.
Here's an example: # echo NO_OSNOISE_WORKLOAD >
/sys/kernel/debug/tracing/osnoise/options # echo timerlat >
/sys/kernel/debug/tracing/current_tracer # cat <
./timerlat_load.py # !/usr/bin/env python3 timerlat_fd =
open("/sys/kernel/tracing/osnoise/per_cpu/cpu0/timerlat_fd", 'r')
timerlat_fd.close(); EOF # ./taskset -c 0 ./timerlat_load.py
BUG: kernel NULL pointer dereference, address: 0000000000000010 #PF:
supervisor read access in kernel mode #PF: error_code(0x0000) - not-
present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 1 PID:
2673 Comm: python3 Not tainted 6.6.13-200.fc39.x86_64 #1 Hardware
name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-1.fc39
04/01/2014 RIP: 0010:hrtimer_active+0xd/0x50 Code: 2e 0f 1f 84 00 00
00 00 00 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90
f3 0f 1e fa 0f 1f 44 00 00 48 8b 57 30 <8b> 42 10 a8 01 74 09 f3 90 8b
42 10 a8 01 75 f7 80 7f 38 00 75 1d RSP: 0018:ffffb031009b7e10 EFLAGS:
00010286 RAX: 000000000002db00 RBX: ffff9118f786db08 RCX:
0000000000000000 RDX: 0000000000000000 RSI: ffff9117a0e64400 RDI:
ffff9118f786db08 RBP: ffff9118f786db80 R08: ffff9117a0ddd420 R09:
ffff9117804d4f70 R10: 0000000000000000 R11: 0000000000000000 R12:
ffff9118f786db08 R13: ffff91178fdd5e20 R14: ffff9117840978c0 R15:
0000000000000000 FS: 00007f2ffbab1740(0000) GS:ffff9118f7840000(0000)
knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0:
0000000080050033 CR2: 0000000000000010 CR3: 00000001b402e000 CR4:
0000000000750ee0 PKRU: 55555554 Call Trace: ? __die+0x23/0x70 ?
page_fault_oops+0x171/0x4e0 ? srso_alias_return_thunk+0x5/0x7f ?
avc_has_extended_perms+0x237/0x520 ? exc_page_fault+0x7f/0x180 ?
asm_exc_page_fault+0x26/0x30 ? hrtimer_active+0xd/0x50
hrtimer_cancel+0x15/0x40 timerlat_fd_release+0x48/0xe0
__fput+0xf5/0x290 __x64_sys_close+0x3d/0x80 do_syscall_64+0x60/0x90 ?
srso_alias_return_thunk+0x5/0x7f ? __x64_sys_ioctl+0x72/0xd0 ?
srso_alias_return_thunk+0x5/0x7f ? syscall_exit_to_user_mode+0x2b/0x40
? srso_alias_return_thunk+0x5/0x7f ? do_syscall_64+0x6c/0x90 ?
srso_alias_return_thunk+0x5/0x7f ?
exit_to_user_mode_prepare+0x142/0x1f0 ?
srso_alias_return_thunk+0x5/0x7f ? syscall_exit_to_user_mode+0x2b/0x40
? srso_alias_return_thunk+0x5/0x7f ? do_syscall_64+0x6c/0x90
entry_SYSCALL_64_after_hwframe+0x6e/0xd8 RIP: 0033:0x7f2ffb321594
Code: 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00
90 f3 0f 1e fa 80 3d d5 cd 0d 00 00 74 13 b8 03 00 00 00 0f 05 <48> 3d
00 f0 ff ff 77 3c c3 0f 1f 00 55 48 89 e5 48 83 ec 10 89 7d RSP:
002b:00007ffe8d8eef18 EFLAGS: 00000202 ORIG_RAX: 0000000000000003 RAX:
ffffffffffffffda RBX: 00007f2ffba4e668 RCX: 00007f2ffb321594 RDX:
0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP:
00007ffe8d8eef40 R08: 0000000000000000 R09: 0000000000000000 R10:
55c926e3167eae79 R11: 0000000000000202 R12: 0000000000000003 R13:
00007ffe8d8ef030 R14: 0000000000000000 R15: 00007f2ffba4e668
CR2: 0000000000000010 ---[ end trace 0000000000000000 ]--- Move
hrtimer_init to timerlat_fd open() to avoid this problem.
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