proc: do not allow negative offsets on /proc/<pid>/environ
__mem_open() which is called by both /proc/<pid>/environ and
/proc/<pid>/mem ->open() handlers will allow the use of negative offsets.
/proc/<pid>/mem has negative offsets but not /proc/<pid>/environ.
Clean this by moving the 'force FMODE_UNSIGNED_OFFSET flag' to mem_open()
to allow negative offsets only on /proc/<pid>/mem.
Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Brad Spengler <spender@grsecurity.net>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 39ee093..1b6c84cb 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -695,8 +695,6 @@
mmput(mm);
}
- /* OK to pass negative loff_t, we can catch out-of-range */
- file->f_mode |= FMODE_UNSIGNED_OFFSET;
file->private_data = mm;
return 0;
@@ -704,7 +702,12 @@
static int mem_open(struct inode *inode, struct file *file)
{
- return __mem_open(inode, file, PTRACE_MODE_ATTACH);
+ int ret = __mem_open(inode, file, PTRACE_MODE_ATTACH);
+
+ /* OK to pass negative loff_t, we can catch out-of-range */
+ file->f_mode |= FMODE_UNSIGNED_OFFSET;
+
+ return ret;
}
static ssize_t mem_rw(struct file *file, char __user *buf,
