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Commit a3b609ef authored by Mateusz Guzik's avatar Mateusz Guzik Committed by Linus Torvalds
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proc read mm's {arg,env}_{start,end} with mmap semaphore taken. 



Only functions doing more than one read are modified.  Consumeres
happened to deal with possibly changing data, but it does not seem like
a good thing to rely on.

Signed-off-by: default avatarMateusz Guzik <mguzik@redhat.com>
Acked-by: default avatarCyrill Gorcunov <gorcunov@openvz.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Jarod Wilson <jarod@redhat.com>
Cc: Jan Stancek <jstancek@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Anshuman Khandual <anshuman.linux@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ddf1d398

fs/proc/base.c

+10 −3
Original line number Diff line number Diff line
@@ -953,6 +953,7 @@ static ssize_t environ_read(struct file *file, char __user *buf, 
	unsigned long src = *ppos;

	int ret = 0;

	struct mm_struct *mm = file->private_data;

	unsigned long env_start, env_end;



	if (!mm)

		return 0;
@@ -964,19 +965,25 @@ static ssize_t environ_read(struct file *file, char __user *buf, 
	ret = 0;

	if (!atomic_inc_not_zero(&mm->mm_users))

		goto free;



	down_read(&mm->mmap_sem);

	env_start = mm->env_start;

	env_end = mm->env_end;

	up_read(&mm->mmap_sem);



	while (count > 0) {

		size_t this_len, max_len;

		int retval;



		if (src >= (mm->env_end - mm->env_start))

		if (src >= (env_end - env_start))

			break;



		this_len = mm->env_end - (mm->env_start + src);

		this_len = env_end - (env_start + src);



		max_len = min_t(size_t, PAGE_SIZE, count);

		this_len = min(max_len, this_len);



		retval = access_remote_vm(mm, (mm->env_start + src),

		retval = access_remote_vm(mm, (env_start + src),

			page, this_len, 0);



		if (retval <= 0) {

mm/util.c

+12 −4
Original line number Diff line number Diff line
@@ -476,17 +476,25 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen) 
	int res = 0;

	unsigned int len;

	struct mm_struct *mm = get_task_mm(task);

	unsigned long arg_start, arg_end, env_start, env_end;

	if (!mm)

		goto out;

	if (!mm->arg_end)

		goto out_mm;	/* Shh! No looking before we're done */



	len = mm->arg_end - mm->arg_start;

	down_read(&mm->mmap_sem);

	arg_start = mm->arg_start;

	arg_end = mm->arg_end;

	env_start = mm->env_start;

	env_end = mm->env_end;

	up_read(&mm->mmap_sem);



	len = arg_end - arg_start;



	if (len > buflen)

		len = buflen;



	res = access_process_vm(task, mm->arg_start, buffer, len, 0);

	res = access_process_vm(task, arg_start, buffer, len, 0);



	/*

	 * If the nul at the end of args has been overwritten, then
@@ -497,10 +505,10 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen) 
		if (len < res) {

			res = len;

		} else {

			len = mm->env_end - mm->env_start;

			len = env_end - env_start;

			if (len > buflen - res)

				len = buflen - res;

			res += access_process_vm(task, mm->env_start,

			res += access_process_vm(task, env_start,

						 buffer+res, len, 0);

			res = strnlen(buffer, res);

		}