linux-kernel - [PATCH 3.10 045/139] fuse: initialize the flock flag in fuse

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Message-Id: <1509571578-4803-1-git-send-email-w@1wt.eu>
Date:   Wed,  1 Nov 2017 22:26:14 +0100
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux@...ck-us.net
Cc:     Mateusz Jurczyk <mjurczyk@...gle.com>,
        Miklos Szeredi <mszeredi@...hat.com>, Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 045/139] fuse: initialize the flock flag in fuse_file on allocation

From: Mateusz Jurczyk <mjurczyk@...gle.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@...gle.com>
Fixes: 37fb3a30b462 ("fuse: fix flock")
Cc: <stable@...r.kernel.org> 
Signed-off-by: Miklos Szeredi <mszeredi@...hat.com>
Signed-off-by: Willy Tarreau <w@....eu>
---
 fs/fuse/file.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 1dce930..ee5c3e9 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -54,7 +54,7 @@ struct fuse_file *fuse_file_alloc(struct fuse_conn *fc)
 {
 	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;
 
-- 
2.8.0.rc2.1.gbe9624a