From 83f918274e4b841d6fb817861ea0c896fba0c179 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@redhat.com>
Date: Tue, 3 Oct 2017 16:15:48 -0700
Subject: [PATCH] exec: binfmt_misc: shift filp_close(interp_file) from
kill_node() to bm_evict_inode()
To ensure that load_misc_binary() can't use the partially destroyed
Node, see also the next patch.
The current logic looks wrong in any case, once we close interp_file it
doesn't make any sense to delay kfree(inode->i_private), this Node is no
longer valid. Even if the MISC_FMT_OPEN_FILE/interp_file checks were
not racy (they are), load_misc_binary() should not try to reopen
->interpreter if MISC_FMT_OPEN_FILE is set but ->interp_file is NULL.
And I can't understand why do we use filp_close(), not fput().
Link: http://lkml.kernel.org/r/20170922143644.GA17216@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ben Woodard <woodard@redhat.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jim Foraker <foraker1@llnl.gov>
Cc: <tdhooge@llnl.gov>
Cc: Travis Gummels <tgummels@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
fs/binfmt_misc.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index 6451e7520e053..203598ccb40ad 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -594,8 +594,13 @@ static struct inode *bm_get_inode(struct super_block *sb, int mode)
static void bm_evict_inode(struct inode *inode)
{
+ Node *e = inode->i_private;
+
+ if ((e->flags & MISC_FMT_OPEN_FILE) && e->interp_file)
+ filp_close(e->interp_file, NULL);
+
clear_inode(inode);
- kfree(inode->i_private);
+ kfree(e);
}
static void kill_node(Node *e)
@@ -606,11 +611,6 @@ static void kill_node(Node *e)
list_del_init(&e->list);
write_unlock(&entries_lock);
- if ((e->flags & MISC_FMT_OPEN_FILE) && e->interp_file) {
- filp_close(e->interp_file, NULL);
- e->interp_file = NULL;
- }
-
dentry = e->dentry;
drop_nlink(d_inode(dentry));
d_drop(dentry);
--
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