4.4-stable review patch. If anyone has any objections, please let me know.
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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 @@ -379,11 +379,6 @@ 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); @@ -1174,16 +1169,25 @@ 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); }
@@ -1206,14 +1210,7 @@ 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); }