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authorMateusz Guzik <mguzik@redhat.com>2016-01-20 15:01:05 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-01-20 17:09:18 -0800
commita3b609ef9f8b1dbfe97034ccad6cd3fe71fbe7ab (patch)
tree0162563ac7cab6364a3ec6df61b4b96a876943f4 /mm
parentddf1d398e517e660207e2c807f76a90df543a217 (diff)
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 'mm')
-rw-r--r--mm/util.c16
1 files changed, 12 insertions, 4 deletions
diff --git a/mm/util.c b/mm/util.c
index 6d1f9200f74e..c108a6542d05 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -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);
}