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Subject[PATCH 4.14 123/165] fuse: Fix oops at process_init_reply()
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Miklos Szeredi <mszeredi@redhat.com>

commit e8f3bd773d22f488724dffb886a1618da85c2966 upstream.

syzbot is hitting NULL pointer dereference at process_init_reply().
This is because deactivate_locked_super() is called before response for
initial request is processed.

Fix this by aborting and waiting for all requests (including FUSE_INIT)
before resetting fc->sb.

Original patch by Tetsuo Handa <penguin-kernel@I-love.SKAURA.ne.jp>.

Reported-by: syzbot <syzbot+b62f08f4d5857755e3bc@syzkaller.appspotmail.com>
Fixes: e27c9d3877a0 ("fuse: fuse: add time_gran to INIT_OUT")
Cc: <stable@vger.kernel.org> # v3.19
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/fuse/inode.c | 25 +++++++++++--------------
1 file changed, 11 insertions(+), 14 deletions(-)

--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -397,11 +397,6 @@ static void fuse_put_super(struct super_
{
struct fuse_conn *fc = get_fuse_conn_super(sb);

- fuse_send_destroy(fc);
-
- fuse_abort_conn(fc);
- fuse_wait_aborted(fc);
-
mutex_lock(&fuse_mutex);
list_del(&fc->entry);
fuse_ctl_remove_conn(fc);
@@ -1198,16 +1193,25 @@ static struct dentry *fuse_mount(struct
return mount_nodev(fs_type, flags, raw_data, fuse_fill_super);
}

-static void fuse_kill_sb_anon(struct super_block *sb)
+static void fuse_sb_destroy(struct super_block *sb)
{
struct fuse_conn *fc = get_fuse_conn_super(sb);

if (fc) {
+ fuse_send_destroy(fc);
+
+ fuse_abort_conn(fc);
+ fuse_wait_aborted(fc);
+
down_write(&fc->killsb);
fc->sb = NULL;
up_write(&fc->killsb);
}
+}

+static void fuse_kill_sb_anon(struct super_block *sb)
+{
+ fuse_sb_destroy(sb);
kill_anon_super(sb);
}

@@ -1230,14 +1234,7 @@ static struct dentry *fuse_mount_blk(str

static void fuse_kill_sb_blk(struct super_block *sb)
{
- struct fuse_conn *fc = get_fuse_conn_super(sb);
-
- if (fc) {
- down_write(&fc->killsb);
- fc->sb = NULL;
- up_write(&fc->killsb);
- }
-
+ fuse_sb_destroy(sb);
kill_block_super(sb);
}


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