4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Mateusz Guzik <mguzik@xxxxxxxxxx>
commit a3b609ef9f8b1dbfe97034ccad6cd3fe71fbe7ab upstream.
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@xxxxxxxxxx>
Acked-by: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: Jarod Wilson <jarod@xxxxxxxxxx>
Cc: Jan Stancek <jstancek@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Anshuman Khandual <anshuman.linux@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/proc/base.c | 13 ++++++++++---
mm/util.c | 16 ++++++++++++----
2 files changed, 22 insertions(+), 7 deletions(-)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -953,6 +953,7 @@ static ssize_t environ_read(struct file
unsigned long src = *ppos;
int ret = 0;
struct mm_struct *mm = file->private_data;
+ unsigned long env_start, env_end;
/* Ensure the process spawned far enough to have an environment. */
if (!mm || !mm->env_end)
@@ -965,19 +966,25 @@ static ssize_t environ_read(struct file
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) {
--- a/mm/util.c
+++ b/mm/util.c
@@ -428,17 +428,25 @@ int get_cmdline(struct task_struct *task
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
@@ -449,10 +457,10 @@ int get_cmdline(struct task_struct *task
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);
}
