From: Alexey Dobriyan <adobriyan@gmail.com>
To: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH 04/10] proc: fix PAGE_SIZE limit of /proc/$PID/cmdline
Date: Thu, 17 Jul 2014 00:32:47 +0300 [thread overview]
Message-ID: <20140716213247.GC21290@p183.telecom.by> (raw)
Convert /proc/$PID/cmdline to seq_file interface.
XXX
This one must be buggy.
seq_file buffer is adjustable, so userspace can execute itself
with huge command line (which can be arbitrarily long now), then read 1 byte.
Voila, whole command line now is in kmalloced/vmalloced memory.
Imposing limit is trivial but equally lame to current PAGE_SIZE limit.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
fs/proc/base.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -200,9 +200,17 @@ static int proc_root_link(struct dentry *dentry, struct path *path)
return result;
}
-static int proc_pid_cmdline(struct task_struct *task, char *buffer)
+static int proc_pid_cmdline(struct seq_file *m, struct pid_namespace *ns,
+ struct pid *pid, struct task_struct *task)
{
- return get_cmdline(task, buffer, PAGE_SIZE);
+ /*
+ * Rely on struct seq_operations::show() being called once
+ * per internal buffer allocation. See single_open(), traverse().
+ *
+ * Rely on internal buffer autoexpansion if it was entirely filled.
+ */
+ m->count += get_cmdline(task, m->buf, m->size);
+ return 0;
}
static int proc_pid_auxv(struct seq_file *m, struct pid_namespace *ns,
@@ -2567,7 +2575,7 @@ static const struct pid_entry tgid_base_stuff[] = {
#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
ONE("syscall", S_IRUSR, proc_pid_syscall),
#endif
- INF("cmdline", S_IRUGO, proc_pid_cmdline),
+ ONE("cmdline", S_IRUGO, proc_pid_cmdline),
ONE("stat", S_IRUGO, proc_tgid_stat),
ONE("statm", S_IRUGO, proc_pid_statm),
REG("maps", S_IRUGO, proc_pid_maps_operations),
@@ -2903,7 +2911,7 @@ static const struct pid_entry tid_base_stuff[] = {
#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
ONE("syscall", S_IRUSR, proc_pid_syscall),
#endif
- INF("cmdline", S_IRUGO, proc_pid_cmdline),
+ ONE("cmdline", S_IRUGO, proc_pid_cmdline),
ONE("stat", S_IRUGO, proc_tid_stat),
ONE("statm", S_IRUGO, proc_pid_statm),
REG("maps", S_IRUGO, proc_tid_maps_operations),
next reply other threads:[~2014-07-16 21:32 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-16 21:32 Alexey Dobriyan [this message]
2014-07-17 22:53 ` [PATCH 04/10] proc: fix PAGE_SIZE limit of /proc/$PID/cmdline Andrew Morton
2014-07-18 20:10 ` Alexey Dobriyan
2014-07-18 20:12 ` [PATCH v2 04/10] proc: convert /proc/$PID/cmdline to seq_file interface Alexey Dobriyan
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