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b=bmzz4TUuhznYAD4P+RMLOFk6Ifhy1aPXO6AwFnJXtKIyEtdN6GlkWLPbUoYrcoZBV dl216lb/hYo6ygy79ydOG6uhoLAO1w7gAakvrOql0CrbwpwLLIf4ty6mqeAx9MpSQA wvwtj7hMnWMRYeLArSRFRfHsvGzO5xtWJuVZz/5N8jkAv8obOe2FgVOiZlJVu02CRv dIr1xLUNMNTVaFAFiaJbcpsCSf6Tn9o7xfAoazABzpMGakcJnu7zxiKgRKZeni6qqT AZu59nK9qaksPT7JdvcH5f3RQZapuzYFSqIi8+hOsX6FOtLBYcI7ZHKzvQ4IS+mO63 dO6U8LAybDl6w== From: SeongJae Park To: Arnd Bergmann Cc: SeongJae Park , Andrew Morton , Arnd Bergmann , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/damon/dbgfs: fix bogus string length Date: Fri, 2 Feb 2024 09:14:02 -0800 Message-Id: <20240202171402.46340-1-sj@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240202124339.892862-1-arnd@kernel.org> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 3C51E1C0012 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: j1ti1qcweacnmurdek7gqnnbczqdjexa X-HE-Tag: 1706894046-823528 X-HE-Meta: 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 wX+WhFHV 6KTU7f2vkjxw66sk7jSC8RkBuxpsNxXbXh2l6NqDX4s6MJPlTd96oCebpefd1S8kgFgbaWiFk7ZRTtg8sPY+WPXLPsp9w4QEHgmRZI8MN/5kdxka7ntiGfcku1gHnsoT69M+NgCWYNkCFmt2iQz5kpznaGGkIpezim1czuD6MwbWvuTrDqneslgJ8YVm7LaSF4cj7iztMHMcLRboRDXDsYLmoSPcL2uj6QdlDf1ts/Xm3ozo= 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: List-Subscribe: List-Unsubscribe: Hi Arnd, On Fri, 2 Feb 2024 13:43:26 +0100 Arnd Bergmann wrote: > From: Arnd Bergmann > > gcc correctly points out that using strnlen() on a fixed size array > is nonsense with an overlong limit: > > mm/damon/dbgfs.c: In function 'damon_dbgfs_deprecated_read': > mm/damon/dbgfs.c:814:19: error: 'strnlen' specified bound 1024 exceeds source size 512 [-Werror=stringop-overread] > 814 | int len = strnlen(kbuf, 1024); > | ^~~~~~~~~~~~~~~~~~~ > mm/damon/dbgfs.c:813:14: note: source object allocated here > 813 | char kbuf[512] = DAMON_DBGFS_DEPRECATION_NOTICE; > | ^~~~ > > In fact, neither of the arbitrary limits are needed here: The first > one can just be a static const string and avoid wasting any more > space then necessary, and the strnlen() can be either strlen() or > sizeof(kbuf)-1, both of which the compiler turns into the same > constant here. Thank you for this fix! > > Fixes: adf9047adfff ("mm/damon/dbgfs: implement deprecation notice file") > Signed-off-by: Arnd Bergmann Reviewed-by: SeongJae Park Thanks, SJ [...]