linux-kernel - huge_count_read_write.c:23:9: warning: 'write' reading 4294967295 bytes from a region of size 1

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Message-ID: <202209200328.JMMJiy4h-lkp@intel.com>
Date:   Tue, 20 Sep 2022 03:26:17 +0800
From:   kernel test robot <lkp@...el.com>
To:     Yuanchu Xie <yuanchu@...gle.com>
Cc:     kbuild-all@...ts.01.org, linux-kernel@...r.kernel.org,
        Shuah Khan <skhan@...uxfoundation.org>,
        SeongJae Park <sj@...nel.org>
Subject: huge_count_read_write.c:23:9: warning: 'write' reading 4294967295
 bytes from a region of size 1

Hi Yuanchu,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   521a547ced6477c54b4b0cc206000406c221b4d6
commit: 678f0cdc572c5fda940cb038d70eebb8d818adc8 selftests/damon: add damon to selftests root Makefile
date:   5 months ago
compiler: gcc-11 (Debian 11.3.0-5) 11.3.0
reproduce:
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=678f0cdc572c5fda940cb038d70eebb8d818adc8
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout 678f0cdc572c5fda940cb038d70eebb8d818adc8
        make O=/tmp/kselftest headers
        make O=/tmp/kselftest -C tools/testing/selftests

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@...el.com>

All warnings (new ones prefixed by >>):

   huge_count_read_write.c: In function 'write_read_with_huge_count':
>> huge_count_read_write.c:23:9: warning: 'write' reading 4294967295 bytes from a region of size 1 [-Wstringop-overread]
      23 |         write(filedesc, "", 0xfffffffful);
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   In file included from huge_count_read_write.c:8:
   /usr/include/unistd.h:367:16: note: in a call to function 'write' declared with attribute 'access (read_only, 2, 3)'
     367 | extern ssize_t write (int __fd, const void *__buf, size_t __n) __wur
         |                ^~~~~
>> huge_count_read_write.c:25:15: warning: 'read' writing 4294967295 bytes into a region of size 25 overflows the destination [-Wstringop-overflow=]
      25 |         ret = read(filedesc, buf, 0xfffffffful);
         |               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   huge_count_read_write.c:14:14: note: destination object 'buf' of size 25
      14 |         char buf[25];
         |              ^~~
   In file included from huge_count_read_write.c:8:
   /usr/include/unistd.h:360:16: note: in a call to function 'read' declared with attribute 'access (write_only, 2, 3)'
     360 | extern ssize_t read (int __fd, void *__buf, size_t __nbytes) __wur
         |                ^~~~

-- 
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https://01.org/lkp

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