[axboe:rw_iter 424/471] kernel/sched/debug.c:141 sched_feat_write() warn: potential spectre issue 'buf' [w]

[axboe:rw_iter 424/471] kernel/sched/debug.c:141 sched_feat_write() 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.git rw_iter
head:   0a49759be1c3b29207758e467fdc1a90d0716d06
commit: dee2a50905cf3505d706c0bdb2648900b643b4d3 [424/471] sched/debug: convert to read/write iterators
:::::: branch date: 7 days ago
:::::: commit date: 7 days ago
config: openrisc-randconfig-r071-20260307 (https://download.01.org/0day-ci/archive/20260313/202603131526.wBA9qa4z-lkp@intel.com/config)
compiler: or1k-linux-gcc (GCC) 15.2.0
smatch: v0.5.0-9004-gb810ac53

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/202603131526.wBA9qa4z-lkp@intel.com/

smatch warnings:
kernel/sched/debug.c:141 sched_feat_write() warn: potential spectre issue 'buf' [w]

vim +/buf +141 kernel/sched/debug.c

d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  125) 
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  126) static ssize_t
dee2a50905cf350 Jens Axboe               2026-03-04  127  sched_feat_write(struct kiocb *iocb, struct iov_iter *from)
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  128) {
dee2a50905cf350 Jens Axboe               2026-03-04  129  	size_t cnt = iov_iter_count(from);
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  130) 	char buf[64];
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  131) 	char *cmp;
8f894bf47dc9e8b Yisheng Xie              2018-05-31  132  	int ret;
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  133) 	struct inode *inode;
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  134) 
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  135) 	if (cnt > 63)
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  136) 		cnt = 63;
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  137) 
dee2a50905cf350 Jens Axboe               2026-03-04  138  	if (!copy_from_iter_full(buf, cnt, from))
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  139) 		return -EFAULT;
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  140) 
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22 @141) 	buf[cnt] = 0;
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  142) 	cmp = strstrip(buf);
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  143) 
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  144) 	/* Ensure the static_key remains in a consistent state */
dee2a50905cf350 Jens Axboe               2026-03-04  145  	inode = file_inode(iocb->ki_filp);
e73e81975f2447e Jiada Wang               2018-07-31  146  	cpus_read_lock();
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  147) 	inode_lock(inode);
8f894bf47dc9e8b Yisheng Xie              2018-05-31  148  	ret = sched_feat_set(cmp);
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  149) 	inode_unlock(inode);
e73e81975f2447e Jiada Wang               2018-07-31  150  	cpus_read_unlock();
8f894bf47dc9e8b Yisheng Xie              2018-05-31  151  	if (ret < 0)
8f894bf47dc9e8b Yisheng Xie              2018-05-31  152  		return ret;
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  153) 
dee2a50905cf350 Jens Axboe               2026-03-04  154  	iocb->ki_pos += cnt;
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  155) 
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  156) 	return cnt;
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  157) }
d6ca41d7922ce01 Steven Rostedt (Red Hat  2016-02-22  158) 

:::::: The code at line 141 was first introduced by commit
:::::: d6ca41d7922ce0110a840ef4f8ec4afdd5a239d3 sched/debug: Move the /sys/kernel/debug/sched_features file setup into debug.c

:::::: TO: Steven Rostedt (Red Hat) <rostedt@goodmis.org>
:::::: CC: Ingo Molnar <mingo@kernel.org>

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