Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp> writes:
> From 904d07a6eb014f3df0c5a1ebfcfd4323276a9a76 Mon Sep 17 00:00:00 2001
> From: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp>
> Date: Tue, 10 Apr 2018 15:15:16 +0900
> Subject: [PATCH] commoncap: Handle memory allocation failure.
>
> syzbot is reporting NULL pointer dereference at xattr_getsecurity() [1],
> for cap_inode_getsecurity() is returning sizeof(struct vfs_cap_data) when
> memory allocation failed. Return -ENOMEM if memory allocation failed.
>
> [1]
> https://syzkaller.appspot.com/bug?id=a55ba438506fe68649a5f50d2d82d56b365e0107
Acked-by: "Eric W. Biederman" <ebied...@xmission.com>
Tetsuo I can pick this up, or do you have preferred path for getting
this change merged?
Serge does this fix look ok to you? I am a bit worried that
might be a bit brittler but I don't see any issues with this change.
Eric
> Signed-off-by: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp>
> Fixes: 8db6c34f1dbc8e06 ("Introduce v3 namespaced file capabilities")
> Reported-by: syzbot <syzbot+9369930ca44f29e60...@syzkaller.appspotmail.com>
> Cc: stable <sta...@vger.kernel.org> # 4.14+
> Cc: Serge E. Hallyn <se...@hallyn.com>
> Cc: Eric W. Biederman <ebied...@xmission.com>
> ---
> security/commoncap.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/security/commoncap.c b/security/commoncap.c
> index 48620c9..1ce701f 100644
> --- a/security/commoncap.c
> +++ b/security/commoncap.c
> @@ -449,6 +449,8 @@ int cap_inode_getsecurity(struct inode *inode, const char
> *name, void **buffer,
> magic |= VFS_CAP_FLAGS_EFFECTIVE;
> memcpy(&cap->data, &nscap->data, sizeof(__le32) * 2 *
> VFS_CAP_U32);
> cap->magic_etc = cpu_to_le32(magic);
> + } else {
> + size = -ENOMEM;
> }
> }
> kfree(tmpbuf);
> --
> 1.8.3.1
