2022-12-26 03:10:51

by Yu Kuai

Subject: [PATCH] block, bfq: fix uaf for bfqq in bfq_exit_icq_bfqq

From: Yu Kuai <[email protected]>

Commit 64dc8c732f5c ("block, bfq: fix possible uaf for 'bfqq->bic'")
will access 'bic->bfqq' in bic_set_bfqq(), however, bfq_exit_icq_bfqq()
can free bfqq first, and then call bic_set_bfqq(), which will cause uaf.

Fix the problem by moving bfq_exit_bfqq() behind bic_set_bfqq().

Fixes: 64dc8c732f5c ("block, bfq: fix possible uaf for 'bfqq->bic'")
Reported-by: Yi Zhang <[email protected]>
Signed-off-by: Yu Kuai <[email protected]>
---
block/bfq-iosched.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 16f43bbc575a..ccf2204477a5 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -5317,8 +5317,8 @@ static void bfq_exit_icq_bfqq(struct bfq_io_cq *bic, bool is_sync)
unsigned long flags;

spin_lock_irqsave(&bfqd->lock, flags);
- bfq_exit_bfqq(bfqd, bfqq);
bic_set_bfqq(bic, NULL, is_sync);
+ bfq_exit_bfqq(bfqd, bfqq);
spin_unlock_irqrestore(&bfqd->lock, flags);
}
}
--
2.31.1

2022-12-26 19:51:09

by Jens Axboe

Subject: Re: [PATCH] block, bfq: fix uaf for bfqq in bfq_exit_icq_bfqq

On Mon, 26 Dec 2022 11:06:05 +0800, Yu Kuai wrote:
> Commit 64dc8c732f5c ("block, bfq: fix possible uaf for 'bfqq->bic'")
> will access 'bic->bfqq' in bic_set_bfqq(), however, bfq_exit_icq_bfqq()
> can free bfqq first, and then call bic_set_bfqq(), which will cause uaf.
>
> Fix the problem by moving bfq_exit_bfqq() behind bic_set_bfqq().
>
>
> [...]

Applied, thanks!

[1/1] block, bfq: fix uaf for bfqq in bfq_exit_icq_bfqq
commit: 246cf66e300b76099b5dbd3fdd39e9a5dbc53f02

Best regards,
--
Jens Axboe

2022-12-26 22:30:21

by Jan Kara

Subject: Re: [PATCH] block, bfq: fix uaf for bfqq in bfq_exit_icq_bfqq

On Mon 26-12-22 11:06:05, Yu Kuai wrote:
> From: Yu Kuai <[email protected]>
>
> Commit 64dc8c732f5c ("block, bfq: fix possible uaf for 'bfqq->bic'")
> will access 'bic->bfqq' in bic_set_bfqq(), however, bfq_exit_icq_bfqq()
> can free bfqq first, and then call bic_set_bfqq(), which will cause uaf.
>
> Fix the problem by moving bfq_exit_bfqq() behind bic_set_bfqq().
>
> Fixes: 64dc8c732f5c ("block, bfq: fix possible uaf for 'bfqq->bic'")
> Reported-by: Yi Zhang <[email protected]>
> Signed-off-by: Yu Kuai <[email protected]>

Thanks for the patch! Feel free to add:

Reviewed-by: Jan Kara <[email protected]>

Honza

> ---
> block/bfq-iosched.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
> index 16f43bbc575a..ccf2204477a5 100644
> --- a/block/bfq-iosched.c
> +++ b/block/bfq-iosched.c
> @@ -5317,8 +5317,8 @@ static void bfq_exit_icq_bfqq(struct bfq_io_cq *bic, bool is_sync)
> unsigned long flags;
>
> spin_lock_irqsave(&bfqd->lock, flags);
> - bfq_exit_bfqq(bfqd, bfqq);
> bic_set_bfqq(bic, NULL, is_sync);
> + bfq_exit_bfqq(bfqd, bfqq);
> spin_unlock_irqrestore(&bfqd->lock, flags);
> }
> }
> --
> 2.31.1
>
--
Jan Kara <[email protected]>
SUSE Labs, CR