* [PATCH] io_uring: fix shift-out-of-bounds when round up cq size
@ 2020-11-24 7:03 Joseph Qi
2020-11-24 8:38 ` Stefano Garzarella
2020-11-24 14:45 ` Jens Axboe
0 siblings, 2 replies; 3+ messages in thread
From: Joseph Qi @ 2020-11-24 7:03 UTC (permalink / raw)
To: Jens Axboe; +Cc: Xiaoguang Wang, io-uring
Abaci Fuzz reported a shift-out-of-bounds BUG in io_uring_create():
[ 59.598207] UBSAN: shift-out-of-bounds in ./include/linux/log2.h:57:13
[ 59.599665] shift exponent 64 is too large for 64-bit type 'long unsigned int'
[ 59.601230] CPU: 0 PID: 963 Comm: a.out Not tainted 5.10.0-rc4+ #3
[ 59.602502] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
[ 59.603673] Call Trace:
[ 59.604286] dump_stack+0x107/0x163
[ 59.605237] ubsan_epilogue+0xb/0x5a
[ 59.606094] __ubsan_handle_shift_out_of_bounds.cold+0xb2/0x20e
[ 59.607335] ? lock_downgrade+0x6c0/0x6c0
[ 59.608182] ? rcu_read_lock_sched_held+0xaf/0xe0
[ 59.609166] io_uring_create.cold+0x99/0x149
[ 59.610114] io_uring_setup+0xd6/0x140
[ 59.610975] ? io_uring_create+0x2510/0x2510
[ 59.611945] ? lockdep_hardirqs_on_prepare+0x286/0x400
[ 59.613007] ? syscall_enter_from_user_mode+0x27/0x80
[ 59.614038] ? trace_hardirqs_on+0x5b/0x180
[ 59.615056] do_syscall_64+0x2d/0x40
[ 59.615940] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 59.617007] RIP: 0033:0x7f2bb8a0b239
This is caused by roundup_pow_of_two() if the input entries larger
enough, e.g. 2^32-1. For sq_entries, it will check first and we allow
at most IORING_MAX_ENTRIES, so it is okay. But for cq_entries, we do
round up first, that may overflow and truncate it to 0, which is not
the expected behavior. So check the cq size first and then do round up.
Fixes: 88ec3211e463 ("io_uring: round-up cq size before comparing with rounded sq size")
Reported-by: Abaci Fuzz <[email protected]>
Signed-off-by: Joseph Qi <[email protected]>
---
fs/io_uring.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index a8c136a..f971589 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -9252,14 +9252,16 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p,
* to a power-of-two, if it isn't already. We do NOT impose
* any cq vs sq ring sizing.
*/
- p->cq_entries = roundup_pow_of_two(p->cq_entries);
- if (p->cq_entries < p->sq_entries)
+ if (!p->cq_entries)
return -EINVAL;
if (p->cq_entries > IORING_MAX_CQ_ENTRIES) {
if (!(p->flags & IORING_SETUP_CLAMP))
return -EINVAL;
p->cq_entries = IORING_MAX_CQ_ENTRIES;
}
+ p->cq_entries = roundup_pow_of_two(p->cq_entries);
+ if (p->cq_entries < p->sq_entries)
+ return -EINVAL;
} else {
p->cq_entries = 2 * p->sq_entries;
}
--
1.8.3.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] io_uring: fix shift-out-of-bounds when round up cq size
2020-11-24 7:03 [PATCH] io_uring: fix shift-out-of-bounds when round up cq size Joseph Qi
@ 2020-11-24 8:38 ` Stefano Garzarella
2020-11-24 14:45 ` Jens Axboe
1 sibling, 0 replies; 3+ messages in thread
From: Stefano Garzarella @ 2020-11-24 8:38 UTC (permalink / raw)
To: Joseph Qi; +Cc: Jens Axboe, Xiaoguang Wang, io-uring
On Tue, Nov 24, 2020 at 03:03:03PM +0800, Joseph Qi wrote:
>Abaci Fuzz reported a shift-out-of-bounds BUG in io_uring_create():
>
>[ 59.598207] UBSAN: shift-out-of-bounds in ./include/linux/log2.h:57:13
>[ 59.599665] shift exponent 64 is too large for 64-bit type 'long unsigned int'
>[ 59.601230] CPU: 0 PID: 963 Comm: a.out Not tainted 5.10.0-rc4+ #3
>[ 59.602502] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
>[ 59.603673] Call Trace:
>[ 59.604286] dump_stack+0x107/0x163
>[ 59.605237] ubsan_epilogue+0xb/0x5a
>[ 59.606094] __ubsan_handle_shift_out_of_bounds.cold+0xb2/0x20e
>[ 59.607335] ? lock_downgrade+0x6c0/0x6c0
>[ 59.608182] ? rcu_read_lock_sched_held+0xaf/0xe0
>[ 59.609166] io_uring_create.cold+0x99/0x149
>[ 59.610114] io_uring_setup+0xd6/0x140
>[ 59.610975] ? io_uring_create+0x2510/0x2510
>[ 59.611945] ? lockdep_hardirqs_on_prepare+0x286/0x400
>[ 59.613007] ? syscall_enter_from_user_mode+0x27/0x80
>[ 59.614038] ? trace_hardirqs_on+0x5b/0x180
>[ 59.615056] do_syscall_64+0x2d/0x40
>[ 59.615940] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>[ 59.617007] RIP: 0033:0x7f2bb8a0b239
>
>This is caused by roundup_pow_of_two() if the input entries larger
>enough, e.g. 2^32-1. For sq_entries, it will check first and we allow
>at most IORING_MAX_ENTRIES, so it is okay. But for cq_entries, we do
>round up first, that may overflow and truncate it to 0, which is not
>the expected behavior. So check the cq size first and then do round up.
>
>Fixes: 88ec3211e463 ("io_uring: round-up cq size before comparing with rounded sq size")
>Reported-by: Abaci Fuzz <[email protected]>
>Signed-off-by: Joseph Qi <[email protected]>
>---
> fs/io_uring.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
>diff --git a/fs/io_uring.c b/fs/io_uring.c
>index a8c136a..f971589 100644
>--- a/fs/io_uring.c
>+++ b/fs/io_uring.c
>@@ -9252,14 +9252,16 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p,
> * to a power-of-two, if it isn't already. We do NOT impose
> * any cq vs sq ring sizing.
> */
>- p->cq_entries = roundup_pow_of_two(p->cq_entries);
>- if (p->cq_entries < p->sq_entries)
>+ if (!p->cq_entries)
> return -EINVAL;
> if (p->cq_entries > IORING_MAX_CQ_ENTRIES) {
> if (!(p->flags & IORING_SETUP_CLAMP))
> return -EINVAL;
> p->cq_entries = IORING_MAX_CQ_ENTRIES;
> }
>+ p->cq_entries = roundup_pow_of_two(p->cq_entries);
>+ if (p->cq_entries < p->sq_entries)
>+ return -EINVAL;
Your changes reflect what we do for sq_entries, so it feels right to do
the same for cq_entries. Also moving the check after the roundup
prevents the issues fixed in 88ec3211e463, so:
Reviewed-by: Stefano Garzarella <[email protected]>
Thanks,
Stefano
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] io_uring: fix shift-out-of-bounds when round up cq size
2020-11-24 7:03 [PATCH] io_uring: fix shift-out-of-bounds when round up cq size Joseph Qi
2020-11-24 8:38 ` Stefano Garzarella
@ 2020-11-24 14:45 ` Jens Axboe
1 sibling, 0 replies; 3+ messages in thread
From: Jens Axboe @ 2020-11-24 14:45 UTC (permalink / raw)
To: Joseph Qi; +Cc: Xiaoguang Wang, io-uring
On 11/24/20 12:03 AM, Joseph Qi wrote:
> Abaci Fuzz reported a shift-out-of-bounds BUG in io_uring_create():
>
> [ 59.598207] UBSAN: shift-out-of-bounds in ./include/linux/log2.h:57:13
> [ 59.599665] shift exponent 64 is too large for 64-bit type 'long unsigned int'
> [ 59.601230] CPU: 0 PID: 963 Comm: a.out Not tainted 5.10.0-rc4+ #3
> [ 59.602502] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
> [ 59.603673] Call Trace:
> [ 59.604286] dump_stack+0x107/0x163
> [ 59.605237] ubsan_epilogue+0xb/0x5a
> [ 59.606094] __ubsan_handle_shift_out_of_bounds.cold+0xb2/0x20e
> [ 59.607335] ? lock_downgrade+0x6c0/0x6c0
> [ 59.608182] ? rcu_read_lock_sched_held+0xaf/0xe0
> [ 59.609166] io_uring_create.cold+0x99/0x149
> [ 59.610114] io_uring_setup+0xd6/0x140
> [ 59.610975] ? io_uring_create+0x2510/0x2510
> [ 59.611945] ? lockdep_hardirqs_on_prepare+0x286/0x400
> [ 59.613007] ? syscall_enter_from_user_mode+0x27/0x80
> [ 59.614038] ? trace_hardirqs_on+0x5b/0x180
> [ 59.615056] do_syscall_64+0x2d/0x40
> [ 59.615940] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> [ 59.617007] RIP: 0033:0x7f2bb8a0b239
>
> This is caused by roundup_pow_of_two() if the input entries larger
> enough, e.g. 2^32-1. For sq_entries, it will check first and we allow
> at most IORING_MAX_ENTRIES, so it is okay. But for cq_entries, we do
> round up first, that may overflow and truncate it to 0, which is not
> the expected behavior. So check the cq size first and then do round up.
Applied, thanks.
--
Jens Axboe
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-11-24 7:03 [PATCH] io_uring: fix shift-out-of-bounds when round up cq size Joseph Qi
2020-11-24 8:38 ` Stefano Garzarella
2020-11-24 14:45 ` Jens Axboe
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