[axboe-block:rw_iter 201/415] drivers/misc/lkdtm/core.c:243 lkdtm_debugfs_entry() warn: potential spectre issue 'buf' [w]

[axboe-block:rw_iter 201/415] drivers/misc/lkdtm/core.c:243 lkdtm_debugfs_entry() warn: potential spectre issue 'buf' [w]

[kernel test robot]

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
TO: Jens Axboe <axboe@kernel.dk>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git rw_iter
head:   8e79f6c3d0a118031e843758491803e38794f6e8
commit: a1a155c91686296745efd6a9fbb865ca4cef6ff5 [201/415] misc: lkdtm: convert to read/write iterators
:::::: branch date: 7 hours ago
:::::: commit date: 26 hours ago
config: x86_64-randconfig-161-20240411 (https://download.01.org/0day-ci/archive/20240412/202404121007.lwFNRpQt-lkp@intel.com/config)
compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Closes: https://lore.kernel.org/r/202404121007.lwFNRpQt-lkp@intel.com/

New smatch warnings:
drivers/misc/lkdtm/core.c:243 lkdtm_debugfs_entry() warn: potential spectre issue 'buf' [w]

Old smatch warnings:
drivers/misc/lkdtm/core.c:318 direct_entry() warn: potential spectre issue 'buf' [w]

vim +/buf +243 drivers/misc/lkdtm/core.c

2b271cb7203dd4 drivers/misc/lkdtm_core.c Arnd Bergmann  2016-07-15  223  
a1a155c9168629 drivers/misc/lkdtm/core.c Jens Axboe     2024-04-05  224  static ssize_t lkdtm_debugfs_entry(struct kiocb *iocb, struct iov_iter *from)
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  225  {
a1a155c9168629 drivers/misc/lkdtm/core.c Jens Axboe     2024-04-05  226  	struct crashpoint *crashpoint = file_inode(iocb->ki_filp)->i_private;
75f98b7ab748a6 drivers/misc/lkdtm_core.c Kees Cook      2017-10-20  227  	const struct crashtype *crashtype = NULL;
a1a155c9168629 drivers/misc/lkdtm/core.c Jens Axboe     2024-04-05  228  	size_t count = iov_iter_count(from);
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  229  	char *buf;
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  230  	int err;
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  231  
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  232  	if (count >= PAGE_SIZE)
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  233  		return -EINVAL;
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  234  
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  235  	buf = (char *)__get_free_page(GFP_KERNEL);
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  236  	if (!buf)
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  237  		return -ENOMEM;
a1a155c9168629 drivers/misc/lkdtm/core.c Jens Axboe     2024-04-05  238  	if (!copy_from_iter_full(buf, count, from)) {
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  239  		free_page((unsigned long) buf);
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  240  		return -EFAULT;
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  241  	}
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  242  	/* NULL-terminate and remove enter */
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05 @243  	buf[count] = '\0';
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  244  	strim(buf);
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  245  
c479e3fd88703c drivers/misc/lkdtm_core.c Kees Cook      2016-06-29  246  	crashtype = find_crashtype(buf);
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  247  	free_page((unsigned long)buf);
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  248  
c479e3fd88703c drivers/misc/lkdtm_core.c Kees Cook      2016-06-29  249  	if (!crashtype)
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  250  		return -EINVAL;
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  251  
c479e3fd88703c drivers/misc/lkdtm_core.c Kees Cook      2016-06-29  252  	err = lkdtm_register_cpoint(crashpoint, crashtype);
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  253  	if (err < 0)
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  254  		return err;
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  255  
a1a155c9168629 drivers/misc/lkdtm/core.c Jens Axboe     2024-04-05  256  	iocb->ki_pos += count;
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  257  
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  258  	return count;
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  259  }
2b271cb7203dd4 drivers/misc/lkdtm_core.c Arnd Bergmann  2016-07-15  260  #endif
0347af4ee39222 drivers/misc/lkdtm.c      Simon Kagstrom 2010-03-05  261  

:::::: The code at line 243 was first introduced by commit
:::::: 0347af4ee3922220f6bfe74b87b526aa709a0365 lkdtm: add debugfs access and loosen KPROBE ties

:::::: TO: Simon Kagstrom <simon.kagstrom@netinsight.net>
:::::: CC: Linus Torvalds <torvalds@linux-foundation.org>

-- 
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https://github.com/intel/lkp-tests/wiki