hostfs: fix memory handling in follow_link()

1) argument should not be freed in any case - the caller already has
it as ->s_fs_info (and uses it a lot afterwards)
2) allocate readlink buffer with kmalloc() - the caller has no way
to tell if it's got that (on absolute symlink) or a result of
kasprintf().  Sure, for SLAB and SLUB kfree() works on results of
kmem_cache_alloc(), but that's not documented anywhere, might change
in the future *and* is already not true for SLOB.

Fixes: 52b209f7b848 ("get rid of hostfs_read_inode()")
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c
index 29e4077..743a005 100644 (file)
--- a/fs/hostfs/hostfs_kern.c
+++ b/fs/hostfs/hostfs_kern.c
@@ -144,7 +144,7 @@ static char *follow_link(char *link)
        char *name, *resolved, *end;
        int n;
 
-       name = __getname();
+       name = kmalloc(PATH_MAX, GFP_KERNEL);
        if (!name) {
                n = -ENOMEM;
                goto out_free;
@@ -173,12 +173,11 @@ static char *follow_link(char *link)
                goto out_free;
        }
 
-       __putname(name);
-       kfree(link);
+       kfree(name);
        return resolved;
 
  out_free:
-       __putname(name);
+       kfree(name);
        return ERR_PTR(n);
 }