[PATCH 4.9 10/92] v9fs_dir_readdir: fix double-free on p9stat_read error

Greg Kroah-Hartman
2018-11-29T14:20:43Z

From: Dominique Martinet <dominique.martinet@cea.fr>

commit 81c99089bce693b94b775b6eb888115d2d540086 upstream.

p9stat_read will call p9stat_free on error, we should only free the
struct content on success.

There also is no need to "p9stat_init" st as the read function will
zero the whole struct for us anyway, so clean up the code a bit while
we are here.

Link: http://lkml.kernel.org/r/1535410108-20650-1-git-send-email-asmadeus@codewreck.org
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Reported-by: syzbot+d4252148d198410b864f@syzkaller.appspotmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/9p/vfs_dir.c | 11 -----------
1 file changed, 11 deletions(-)

--- a/fs/9p/vfs_dir.c
+++ b/fs/9p/vfs_dir.c
@@ -76,15 +76,6 @@ static inline int dt_type(struct p9_wsta
return rettype;
}

-static void p9stat_init(struct p9_wstat *stbuf)
-{
- stbuf->name = NULL;
- stbuf->uid = NULL;
- stbuf->gid = NULL;
- stbuf->muid = NULL;
- stbuf->extension = NULL;
-}
-
/**
* v9fs_alloc_rdir_buf - Allocate buffer used for read and readdir
* @filp: opened file structure
@@ -145,12 +136,10 @@ static int v9fs_dir_readdir(struct file
rdir->tail = n;
}
while (rdir->head < rdir->tail) {
- p9stat_init(&st);
err = p9stat_read(fid->clnt, rdir->buf + rdir->head,
rdir->tail - rdir->head, &st);
if (err) {
p9_debug(P9_DEBUG_VFS, "returned %d\n", err);
- p9stat_free(&st);
return -EIO;
}
reclen = st.size+2;