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Subject[PATCH 2/5] 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is no longer valid.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().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
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 f4de5ae..040ed26 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -591,8 +591,13 @@ 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)
@@ -603,11 +608,6 @@ 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);
--
2.5.0
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