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Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 CC: , , , Subject: Re: [PATCH] mm: Return early in truncate_pagecache if newsize overflows Content-Language: en-US To: , References: <20230306113317.2295343-1-mawupeng1@huawei.com> From: mawupeng In-Reply-To: <20230306113317.2295343-1-mawupeng1@huawei.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.178.120] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpemm500014.china.huawei.com (7.185.36.153) X-CFilter-Loop: Reflected X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 15E88A000D X-Rspam-User: X-Stat-Signature: 1axja8gj3zhwmcbbjrzwd16rjh4rhttw X-HE-Tag: 1679572584-26172 X-HE-Meta: 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 5ZEtDk+d SBMi4bsGEvUJZYdVpDmZN9CbMMOlD8J3cp1pjUHUFWHdmCBfz1unnsMTRSTvswB9IQr5J2poJqPHNy8LyeN+KaozALLg3DtIyXJDngGbSHozoGeTg6tXc+VLdZTsKJXy8WVTSe/l1XSb2Cgvmm0mjX3oUhuhmIuz1Tod2x586FQ/Sfkt1Q9QV+nJJygG4dmb5ZZ1RPxxUd6k7CQ7NyiA0CZgZjg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi maintainers. Kindly ping. On 2023/3/6 19:33, Wupeng Ma wrote: > From: Ma Wupeng > > Our own test reports a UBSAN in truncate_pagecache: > > UBSAN: Undefined behaviour in mm/truncate.c:788:9 > signed integer overflow: > 9223372036854775807 + 1 cannot be represented in type 'long long int' > > Call Trace: > truncate_pagecache+0xd4/0xe0 > truncate_setsize+0x70/0x88 > simple_setattr+0xdc/0x100 > notify_change+0x654/0xb00 > do_truncate+0x108/0x1a8 > do_sys_ftruncate+0x2ec/0x4a0 > __arm64_sys_ftruncate+0x5c/0x80 > > For huge file which pass LONG_MAX to ftruncate, truncate_pagecache() will > be called to truncate with newsize be LONG_MAX which will lead to > overflow for holebegin: > > loff_t holebegin = round_up(newsize, PAGE_SIZE); > > Since there is no meaning to truncate a file to LONG_MAX, return here > to avoid burn a bunch of cpu cycles. > > Signed-off-by: Ma Wupeng > --- > mm/truncate.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/mm/truncate.c b/mm/truncate.c > index 7b4ea4c4a46b..99b6ce2d669b 100644 > --- a/mm/truncate.c > +++ b/mm/truncate.c > @@ -730,6 +730,9 @@ void truncate_pagecache(struct inode *inode, loff_t newsize) > struct address_space *mapping = inode->i_mapping; > loff_t holebegin = round_up(newsize, PAGE_SIZE); > > + if (holebegin < 0) > + return; > + > /* > * unmap_mapping_range is called twice, first simply for > * efficiency so that truncate_inode_pages does fewer