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[146.115.88.66]) by smtp.gmail.com with ESMTPSA id i20sm1342859qka.17.2020.08.12.00.13.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 Aug 2020 00:13:08 -0700 (PDT) Date: Wed, 12 Aug 2020 03:13:06 -0400 From: Peilin Ye To: Greg Kroah-Hartman Cc: linux-fsdevel@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, syzkaller-bugs@googlegroups.com, linux-kernel@vger.kernel.org Subject: Re: [Linux-kernel-mentees] [PATCH] hfs, hfsplus: Fix NULL pointer dereference in hfs_find_init() Message-ID: <20200812071306.GA869606@PWN> References: <20200812065556.869508-1-yepeilin.cs@gmail.com> <20200812070827.GA1304640@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200812070827.GA1304640@kroah.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 12, 2020 at 09:08:27AM +0200, Greg Kroah-Hartman wrote: > On Wed, Aug 12, 2020 at 02:55:56AM -0400, Peilin Ye wrote: > > Prevent hfs_find_init() from dereferencing `tree` as NULL. > > > > Reported-and-tested-by: syzbot+7ca256d0da4af073b2e2@syzkaller.appspotmail.com > > Signed-off-by: Peilin Ye > > --- > > fs/hfs/bfind.c | 3 +++ > > fs/hfsplus/bfind.c | 3 +++ > > 2 files changed, 6 insertions(+) > > > > diff --git a/fs/hfs/bfind.c b/fs/hfs/bfind.c > > index 4af318fbda77..880b7ea2c0fc 100644 > > --- a/fs/hfs/bfind.c > > +++ b/fs/hfs/bfind.c > > @@ -16,6 +16,9 @@ int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd) > > { > > void *ptr; > > > > + if (!tree) > > + return -EINVAL; > > + > > fd->tree = tree; > > fd->bnode = NULL; > > ptr = kmalloc(tree->max_key_len * 2 + 4, GFP_KERNEL); > > diff --git a/fs/hfsplus/bfind.c b/fs/hfsplus/bfind.c > > index ca2ba8c9f82e..85bef3e44d7a 100644 > > --- a/fs/hfsplus/bfind.c > > +++ b/fs/hfsplus/bfind.c > > @@ -16,6 +16,9 @@ int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd) > > { > > void *ptr; > > > > + if (!tree) > > + return -EINVAL; > > + > > How can tree ever be NULL in these calls? Shouldn't that be fixed as > the root problem here? I see, I will try to figure out what is going on with the reproducer. Thank you, Peilin Ye