(When I was testing with syzkaller, I found a lot of ubsan problems. Here
is one of them. I am not sure if it needs to be fixed and how it will be
fixed. So I sent this patch to ask your opinion.)
Syzkaller reported a UBSAN bug below, which was mainly caused by a large
negative number passed to the timeout of the io_getevents system call.
================================================================================
UBSAN: Undefined behaviour in ./include/linux/ktime.h:42:14
signed integer overflow:
-8427032702788048137 * 1000000000 cannot be represented in type 'long long int'
CPU: 3 PID: 11668 Comm: syz-executor0 Not tainted 4.19.18-514.55.6.9.x86_64+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0xca/0x13e lib/dump_stack.c:113
ubsan_epilogue+0xe/0x81 lib/ubsan.c:159
handle_overflow+0x193/0x1e2 lib/ubsan.c:190
ktime_set include/linux/ktime.h:42 [inline]
timespec64_to_ktime include/linux/ktime.h:78 [inline]
do_io_getevents+0x307/0x390 fs/aio.c:2043
__do_sys_io_getevents fs/aio.c:2080 [inline]
__se_sys_io_getevents fs/aio.c:2068 [inline]
__x64_sys_io_getevents+0x163/0x250 fs/aio.c:2068
do_syscall_64+0xc8/0x580 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x462589
Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fde9b04ec58 EFLAGS: 00000246 ORIG_RAX: 00000000000000d0
RAX: ffffffffffffffda RBX: 000000000072bf00 RCX: 0000000000462589
RDX: 0000000000000006 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000005 R08: 0000000020000100 R09: 0000000000000000
R10: 0000000020000040 R11: 0000000000000246 R12: 00007fde9b04f6bc
R13: 00000000004bd1f0 R14: 00000000006f6b60 R15: 00000000ffffffff
================================================================================
bond0 (unregistering): Released all slaves
The timeout described in "man io_getevents" does not say whether it
can be negative or not, but as a waiting time, a negative number has
no meaning. So I add check to avoid this case.
Signed-off-by: Tan Xiaojun <[email protected]>
---
fs/aio.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/aio.c b/fs/aio.c
index aaaaf4d..28e0fa6 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -2078,10 +2078,15 @@ static long do_io_getevents(aio_context_t ctx_id,
struct io_event __user *events,
struct timespec64 *ts)
{
- ktime_t until = ts ? timespec64_to_ktime(*ts) : KTIME_MAX;
+ ktime_t until;
struct kioctx *ioctx = lookup_ioctx(ctx_id);
long ret = -EINVAL;
+ if (ts && !timespec64_valid(ts))
+ return -EINVAL;
+
+ until = ts ? timespec64_to_ktime(*ts) : KTIME_MAX;
+
if (likely(ioctx)) {
if (likely(min_nr <= nr && min_nr >= 0))
ret = read_events(ioctx, min_nr, nr, events, until);
--
2.7.4
Tan Xiaojun <[email protected]> writes:
> (When I was testing with syzkaller, I found a lot of ubsan problems. Here
> is one of them. I am not sure if it needs to be fixed and how it will be
> fixed. So I sent this patch to ask your opinion.)
>
> Syzkaller reported a UBSAN bug below, which was mainly caused by a large
> negative number passed to the timeout of the io_getevents system call.
>
> ================================================================================
> UBSAN: Undefined behaviour in ./include/linux/ktime.h:42:14
> signed integer overflow:
> -8427032702788048137 * 1000000000 cannot be represented in type 'long long int'
> CPU: 3 PID: 11668 Comm: syz-executor0 Not tainted 4.19.18-514.55.6.9.x86_64+ #1
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
> Call Trace:
> __dump_stack lib/dump_stack.c:77 [inline]
> dump_stack+0xca/0x13e lib/dump_stack.c:113
> ubsan_epilogue+0xe/0x81 lib/ubsan.c:159
> handle_overflow+0x193/0x1e2 lib/ubsan.c:190
> ktime_set include/linux/ktime.h:42 [inline]
> timespec64_to_ktime include/linux/ktime.h:78 [inline]
> do_io_getevents+0x307/0x390 fs/aio.c:2043
> __do_sys_io_getevents fs/aio.c:2080 [inline]
> __se_sys_io_getevents fs/aio.c:2068 [inline]
> __x64_sys_io_getevents+0x163/0x250 fs/aio.c:2068
> do_syscall_64+0xc8/0x580 arch/x86/entry/common.c:290
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x462589
> Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fde9b04ec58 EFLAGS: 00000246 ORIG_RAX: 00000000000000d0
> RAX: ffffffffffffffda RBX: 000000000072bf00 RCX: 0000000000462589
> RDX: 0000000000000006 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: 0000000000000005 R08: 0000000020000100 R09: 0000000000000000
> R10: 0000000020000040 R11: 0000000000000246 R12: 00007fde9b04f6bc
> R13: 00000000004bd1f0 R14: 00000000006f6b60 R15: 00000000ffffffff
> ================================================================================
> bond0 (unregistering): Released all slaves
>
> The timeout described in "man io_getevents" does not say whether it
> can be negative or not, but as a waiting time, a negative number has
> no meaning. So I add check to avoid this case.
It's embarrassing that this bug is still present. See, for example,
this discussion, started in 2015:
https://lore.kernel.org/lkml/CACT4Y+bBxVYLQ6LtOKrKtnLthqLHcw-BMp3aqP3mjdAvr9FULQ@mail.gmail.com/
I could swear it was brought up again since then, but I can't find
records of that.
> Signed-off-by: Tan Xiaojun <[email protected]>
> ---
> fs/aio.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/fs/aio.c b/fs/aio.c
> index aaaaf4d..28e0fa6 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -2078,10 +2078,15 @@ static long do_io_getevents(aio_context_t ctx_id,
> struct io_event __user *events,
> struct timespec64 *ts)
> {
> - ktime_t until = ts ? timespec64_to_ktime(*ts) : KTIME_MAX;
> + ktime_t until;
> struct kioctx *ioctx = lookup_ioctx(ctx_id);
> long ret = -EINVAL;
>
> + if (ts && !timespec64_valid(ts))
> + return -EINVAL;
> +
> + until = ts ? timespec64_to_ktime(*ts) : KTIME_MAX;
> +
> if (likely(ioctx)) {
> if (likely(min_nr <= nr && min_nr >= 0))
> ret = read_events(ioctx, min_nr, nr, events, until);
Looks good to me. Thanks for fixing this.
Reviewed-by: Jeff Moyer <[email protected]>
On 2019/2/19 4:33, Jeff Moyer wrote:
> Tan Xiaojun <[email protected]> writes:
>
>> (When I was testing with syzkaller, I found a lot of ubsan problems. Here
>> is one of them. I am not sure if it needs to be fixed and how it will be
>> fixed. So I sent this patch to ask your opinion.)
>>
>> Syzkaller reported a UBSAN bug below, which was mainly caused by a large
>> negative number passed to the timeout of the io_getevents system call.
>>
>> ================================================================================
>> UBSAN: Undefined behaviour in ./include/linux/ktime.h:42:14
>> signed integer overflow:
>> -8427032702788048137 * 1000000000 cannot be represented in type 'long long int'
>> CPU: 3 PID: 11668 Comm: syz-executor0 Not tainted 4.19.18-514.55.6.9.x86_64+ #1
>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
>> Call Trace:
>> __dump_stack lib/dump_stack.c:77 [inline]
>> dump_stack+0xca/0x13e lib/dump_stack.c:113
>> ubsan_epilogue+0xe/0x81 lib/ubsan.c:159
>> handle_overflow+0x193/0x1e2 lib/ubsan.c:190
>> ktime_set include/linux/ktime.h:42 [inline]
>> timespec64_to_ktime include/linux/ktime.h:78 [inline]
>> do_io_getevents+0x307/0x390 fs/aio.c:2043
>> __do_sys_io_getevents fs/aio.c:2080 [inline]
>> __se_sys_io_getevents fs/aio.c:2068 [inline]
>> __x64_sys_io_getevents+0x163/0x250 fs/aio.c:2068
>> do_syscall_64+0xc8/0x580 arch/x86/entry/common.c:290
>> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>> RIP: 0033:0x462589
>> Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
>> RSP: 002b:00007fde9b04ec58 EFLAGS: 00000246 ORIG_RAX: 00000000000000d0
>> RAX: ffffffffffffffda RBX: 000000000072bf00 RCX: 0000000000462589
>> RDX: 0000000000000006 RSI: 0000000000000000 RDI: 0000000000000000
>> RBP: 0000000000000005 R08: 0000000020000100 R09: 0000000000000000
>> R10: 0000000020000040 R11: 0000000000000246 R12: 00007fde9b04f6bc
>> R13: 00000000004bd1f0 R14: 00000000006f6b60 R15: 00000000ffffffff
>> ================================================================================
>> bond0 (unregistering): Released all slaves
>>
>> The timeout described in "man io_getevents" does not say whether it
>> can be negative or not, but as a waiting time, a negative number has
>> no meaning. So I add check to avoid this case.
>
> It's embarrassing that this bug is still present. See, for example,
> this discussion, started in 2015:
> https://lore.kernel.org/lkml/CACT4Y+bBxVYLQ6LtOKrKtnLthqLHcw-BMp3aqP3mjdAvr9FULQ@mail.gmail.com/
>
> I could swear it was brought up again since then, but I can't find
> records of that.
>
Yes. I will add this, thank you.
>> Signed-off-by: Tan Xiaojun <[email protected]>
>> ---
>> fs/aio.c | 7 ++++++-
>> 1 file changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/aio.c b/fs/aio.c
>> index aaaaf4d..28e0fa6 100644
>> --- a/fs/aio.c
>> +++ b/fs/aio.c
>> @@ -2078,10 +2078,15 @@ static long do_io_getevents(aio_context_t ctx_id,
>> struct io_event __user *events,
>> struct timespec64 *ts)
>> {
>> - ktime_t until = ts ? timespec64_to_ktime(*ts) : KTIME_MAX;
>> + ktime_t until;
>> struct kioctx *ioctx = lookup_ioctx(ctx_id);
>> long ret = -EINVAL;
>>
>> + if (ts && !timespec64_valid(ts))
>> + return -EINVAL;
>> +
>> + until = ts ? timespec64_to_ktime(*ts) : KTIME_MAX;
>> +
>> if (likely(ioctx)) {
>> if (likely(min_nr <= nr && min_nr >= 0))
>> ret = read_events(ioctx, min_nr, nr, events, until);
>
> Looks good to me. Thanks for fixing this.
>
> Reviewed-by: Jeff Moyer <[email protected]>
Thank you for your reply, I went out for a trip last week. I will send it
officially immediately.
Xiaojun.
>
> .
>