diff options
| author | Mateusz Guzik <mguzik@redhat.com> | 2016-01-21 00:01:05 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-01-21 02:09:18 +0100 |
| commit | a3b609ef9f8b1dbfe97034ccad6cd3fe71fbe7ab (patch) | |
| tree | 0162563ac7cab6364a3ec6df61b4b96a876943f4 /fs/proc | |
| parent | prctl: take mmap sem for writing to protect against others (diff) | |
| download | linux-a3b609ef9f8b1dbfe97034ccad6cd3fe71fbe7ab.tar.xz linux-a3b609ef9f8b1dbfe97034ccad6cd3fe71fbe7ab.zip | |
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: Mateusz Guzik <mguzik@redhat.com>
Acked-by: Cyrill 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc')
| -rw-r--r-- | fs/proc/base.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index e665097c1da5..4f764c2ac1a5 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -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) { |