[PATCH 3.18 02/16] fuse: initialize the flock flag in fuse_file on allocation

Greg Kroah-Hartman
2017-08-15T02:00:33Z

From: Mateusz Jurczyk <mjurczyk@google.com>

commit 68227c03cba84a24faf8a7277d2b1a03c8959c2c upstream.

Before the patch, the flock flag could remain uninitialized for the
lifespan of the fuse_file allocation. Unless set to true in
fuse_file_flock(), it would remain in an indeterminate state until read in
an if statement in fuse_release_common(). This could consequently lead to
taking an unexpected branch in the code.

The bug was discovered by a runtime instrumentation designed to detect use
of uninitialized memory in the kernel.

Signed-off-by: Mateusz Jurczyk <mjurczyk@google.com>
Fixes: 37fb3a30b462 ("fuse: fix flock")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/fuse/file.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -54,7 +54,7 @@ struct fuse_file *fuse_file_alloc(struct
{
struct fuse_file *ff;

- ff = kmalloc(sizeof(struct fuse_file), GFP_KERNEL);
+ ff = kzalloc(sizeof(struct fuse_file), GFP_KERNEL);
if (unlikely(!ff))
return NULL;