[PATCH] proc_readfd_common() race fix

Since we drop the rcu_read_lock inside the loop, we can't assume
that files->fdt will remain unchanged (and not freed) between
iterations.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 1 insertions, 3 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 81d7d145292a..7313c62e3e9d 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1626,7 +1626,6 @@ static int proc_readfd_common(struct file * filp, void * dirent,
         unsigned int fd, ino;
         int retval;
         struct files_struct * files;
-        struct fdtable *fdt;
 
         retval = -ENOENT;
         if (!p)
@@ -1649,9 +1648,8 @@ static int proc_readfd_common(struct file * filp, void * dirent,
                         if (!files)
                                 goto out;
                         rcu_read_lock();
-                        fdt = files_fdtable(files);
                         for (fd = filp->f_pos-2;
-                             fd < fdt->max_fds;
+                             fd < files_fdtable(files)->max_fds;
                              fd++, filp->f_pos++) {
                                 char name[PROC_NUMBUF];
                                 int len;