From: Li Nan <linan122@huawei.com>
To: <tj@kernel.org>, <josef@toxicpanda.com>, <axboe@kernel.dk>
Cc: <cgroups@vger.kernel.org>, <linux-block@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <linan122@huawei.com>,
<yukuai3@huawei.com>, <yi.zhang@huawei.com>
Subject: [PATCH -next 5/8] blk-iocost: fix divide by 0 error in calc_lcoefs()
Date: Mon, 28 Nov 2022 23:44:31 +0800 [thread overview]
Message-ID: <20221128154434.4177442-6-linan122@huawei.com> (raw)
In-Reply-To: <20221128154434.4177442-1-linan122@huawei.com>
echo max of u64 to cost.model can cause divide by 0 error.
# echo 8:0 rbps=18446744073709551615 > /sys/fs/cgroup/io.cost.model
divide error: 0000 [#1] PREEMPT SMP
RIP: 0010:calc_lcoefs+0x4c/0xc0
Call Trace:
<TASK>
ioc_refresh_params+0x2b3/0x4f0
ioc_cost_model_write+0x3cb/0x4c0
? _copy_from_iter+0x6d/0x6c0
? kernfs_fop_write_iter+0xfc/0x270
cgroup_file_write+0xa0/0x200
kernfs_fop_write_iter+0x17d/0x270
vfs_write+0x414/0x620
ksys_write+0x73/0x160
__x64_sys_write+0x1e/0x30
do_syscall_64+0x35/0x80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
calc_lcoefs() uses the input value of cost.model in DIV_ROUND_UP_ULL,
overflow would happen if bps plus IOC_PAGE_SIZE is greater than
ULLONG_MAX, it can cause divide by 0 error.I_LCOEF_MAX is introduced to
prevent it.
Signed-off-by: Li Nan <linan122@huawei.com>
---
block/blk-iocost.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index a645184aba4a..a4fa17ebb2fa 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -306,6 +306,9 @@ enum {
IOC_PAGE_SIZE = 1 << IOC_PAGE_SHIFT,
IOC_SECT_TO_PAGE_SHIFT = IOC_PAGE_SHIFT - SECTOR_SHIFT,
+ /* avoid overflow */
+ I_LCOEF_MAX = ULLONG_MAX - IOC_PAGE_SIZE,
+
/* if apart further than 16M, consider randio for linear model */
LCOEF_RANDIO_PAGES = 4096,
};
@@ -3431,6 +3434,8 @@ static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input,
goto out_unlock;
}
+ if (v > I_LCOEF_MAX)
+ goto out_unlock;
u[tok] = v;
user = true;
}
--
2.31.1
next prev parent reply other threads:[~2022-11-28 15:24 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-28 15:44 [PATCH -next 0/8] iocost bugfix Li Nan
2022-11-28 15:44 ` [PATCH -next 1/8] blk-iocost: cleanup ioc_qos_write() and ioc_cost_model_write() Li Nan
2022-11-28 15:44 ` [PATCH -next 2/8] blk-iocost: improve hanlder of match_u64() Li Nan
2022-11-28 15:44 ` [PATCH -next 3/8] blk-iocost: don't allow to configure bio based device Li Nan
2022-11-28 15:44 ` [PATCH -next 4/8] blk-iocost: read params inside lock in sysfs apis Li Nan
2022-11-28 15:44 ` Li Nan [this message]
2022-11-28 15:44 ` [PATCH -next 6/8] blk-iocost: change div64_u64 to DIV64_U64_ROUND_UP in ioc_refresh_params() Li Nan
2022-11-28 15:44 ` [PATCH -next 7/8] blk-iocost: fix possible UAF in ioc_pd_free Li Nan
2022-11-29 12:18 ` Yu Kuai
2022-11-28 15:44 ` [PATCH -next 8/8] block: fix null-pointer dereference in ioc_pd_init Li Nan
2022-11-29 11:23 ` kernel test robot
2022-11-29 14:25 ` Christoph Hellwig
2022-11-30 1:32 ` Yu Kuai
2022-11-30 15:59 ` Christoph Hellwig
2022-11-30 0:50 ` kernel test robot
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