From: Al Viro <viro@zeniv.linux.org.uk>
To: Peter Zijlstra <peterz@infradead.org>
Cc: mingo@kernel.org, mgorman@suse.de, juri.lelli@redhat.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
rostedt@goodmis.org, bsegall@google.com, bristot@redhat.com,
joshdon@google.com, valentin.schneider@arm.com,
linux-kernel@vger.kernel.org, greg@kroah.com
Subject: Re: [PATCH 6/9] debugfs: Implement debugfs_create_str()
Date: Sat, 27 Mar 2021 22:24:45 +0000 [thread overview]
Message-ID: <YF+wrUjnGTsH6FGT@zeniv-ca.linux.org.uk> (raw)
In-Reply-To: <20210326103935.183934395@infradead.org>
On Fri, Mar 26, 2021 at 11:33:58AM +0100, Peter Zijlstra wrote:
> +again:
> + rcu_read_lock();
> + str = rcu_dereference(*(char **)file->private_data);
> + len = strlen(str) + 1;
> +
> + if (!copy || copy_len < len) {
> + rcu_read_unlock();
> + kfree(copy);
> + copy = kmalloc(len + 1, GFP_KERNEL);
> + if (!copy) {
> + debugfs_file_put(dentry);
> + return -ENOMEM;
> + }
> + copy_len = len;
> + goto again;
> + }
> +
> + strncpy(copy, str, len);
> + copy[len] = '\n';
> + copy[len+1] = '\0';
> + rcu_read_unlock();
*Ow*
If the string can't change under you, what is RCU use about?
And if it can, any use of string functions is asking for serious
trouble; they are *not* guaranteed to be safe when any of the strings
involved might be modified under them.
next prev parent reply other threads:[~2021-03-27 22:26 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-26 10:33 [PATCH 0/9] sched: Clean up SCHED_DEBUG Peter Zijlstra
2021-03-26 10:33 ` [PATCH 1/9] sched/numa: Allow runtime enabling/disabling of NUMA balance without SCHED_DEBUG Peter Zijlstra
2021-03-26 10:33 ` [PATCH 2/9] sched: Remove sched_schedstats sysctl out from under SCHED_DEBUG Peter Zijlstra
2021-03-26 10:33 ` [PATCH 3/9] sched: Dont make LATENCYTOP select SCHED_DEBUG Peter Zijlstra
2021-03-26 10:33 ` [PATCH 4/9] sched: Move SCHED_DEBUG to debugfs Peter Zijlstra
2021-03-26 11:06 ` Greg KH
2021-04-07 10:46 ` Valentin Schneider
2021-04-07 12:26 ` Peter Zijlstra
2021-04-07 12:57 ` Valentin Schneider
2021-03-26 10:33 ` [PATCH 5/9] sched,preempt: Move preempt_dynamic to debug.c Peter Zijlstra
2021-03-26 10:33 ` [PATCH 6/9] debugfs: Implement debugfs_create_str() Peter Zijlstra
2021-03-26 11:05 ` Greg KH
2021-03-26 11:18 ` Peter Zijlstra
2021-03-26 11:30 ` Greg KH
2021-03-26 11:38 ` [PATCH v2 " Peter Zijlstra
2021-03-26 12:18 ` Greg KH
2021-03-26 12:53 ` Rasmus Villemoes
2021-03-26 12:57 ` Greg KH
2021-03-26 13:10 ` Rasmus Villemoes
2021-03-26 14:12 ` Peter Zijlstra
2021-03-26 14:19 ` Greg KH
2021-03-26 14:22 ` Peter Zijlstra
2021-03-26 14:58 ` Rasmus Villemoes
2021-03-26 15:19 ` Peter Zijlstra
2021-03-27 10:41 ` Greg KH
2021-03-26 14:50 ` [PATCH v3 " Peter Zijlstra
2021-03-27 10:42 ` Greg KH
2021-03-27 22:24 ` Al Viro [this message]
2021-03-28 0:33 ` [PATCH " Steven Rostedt
2021-03-26 10:33 ` [PATCH 7/9] sched,debug: Convert sysctl sched_domains to debugfs Peter Zijlstra
2021-03-26 13:11 ` Dietmar Eggemann
2021-04-07 10:46 ` Valentin Schneider
2021-04-07 12:18 ` Peter Zijlstra
2021-03-26 10:34 ` [PATCH 8/9] sched: Move /proc/sched_debug " Peter Zijlstra
2021-03-26 11:05 ` Greg KH
2021-03-26 10:34 ` [PATCH 9/9] sched,fair: Alternative sched_slice() Peter Zijlstra
2021-03-26 12:08 ` Dietmar Eggemann
2021-03-26 14:07 ` Peter Zijlstra
2021-03-26 15:37 ` Vincent Guittot
2021-03-26 18:30 ` Peter Zijlstra
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