[PATCH 2/2] 9p: Fix writeback fid incorrectly being attached to dentry

From: Dominique Martinet
Date: Thu Nov 19 2020 - 11:07:25 EST


v9fs_dir_release needs fid->ilist to have been initialized for filp's
fid, not the inode's writeback fid's.

With refcounting this can be improved on later but this appears to fix
null deref issues.

Fixes: xxx ("fs/9p: track open fids")
Signed-off-by: Dominique Martinet <asmadeus@xxxxxxxxxxxxx>
---
(note: fixes tag can't be filled here, will be corrected later)
fs/9p/vfs_file.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index b0ef225cecd0..c5e49c88688d 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -46,7 +46,7 @@ int v9fs_file_open(struct inode *inode, struct file *file)
int err;
struct v9fs_inode *v9inode;
struct v9fs_session_info *v9ses;
- struct p9_fid *fid;
+ struct p9_fid *fid, *writeback_fid;
int omode;

p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, file);
@@ -85,13 +85,13 @@ int v9fs_file_open(struct inode *inode, struct file *file)
* because we want write after unlink usecase
* to work.
*/
- fid = v9fs_writeback_fid(file_dentry(file));
+ writeback_fid = v9fs_writeback_fid(file_dentry(file));
if (IS_ERR(fid)) {
err = PTR_ERR(fid);
mutex_unlock(&v9inode->v_mutex);
goto out_error;
}
- v9inode->writeback_fid = (void *) fid;
+ v9inode->writeback_fid = (void *) writeback_fid;
}
mutex_unlock(&v9inode->v_mutex);
if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
--
2.28.0