Message ID | 18c1b112032a685518548760890547fdbf292b85.1502739025.git.pabeni@redhat.com |
---|---|
State | Accepted, archived |
Delegated to: | David Miller |
Headers | show |
On Mon, 2017-08-14 at 21:31 +0200, Paolo Abeni wrote: > From: Al Viro <viro@ZenIV.linux.org.uk> > > copy_linear_skb() is broken; both of its callers actually > expect 'len' to be the amount we are trying to copy, > not the offset of the end. > Fix it keeping the meanings of arguments in sync with what the > callers (both of them) expect. > Also restore a saner behavior on EFAULT (i.e. preserving > the iov_iter position in case of failure): > > The commit fd851ba9caa9 ("udp: harden copy_linear_skb()") > avoids the more destructive effect of the buggy > copy_linear_skb(), e.g. no more invalid memory access, but > said function still behaves incorrectly: when peeking with > offset it can fail with EINVAL instead of copying the > appropriate amount of memory. > > Reported-by: Sasha Levin <alexander.levin@verizon.com> > Fixes: b65ac44674dd ("udp: try to avoid 2 cache miss on dequeue") > Fixes: fd851ba9caa9 ("udp: harden copy_linear_skb()") > Signed-off-by: Al Viro <viro@ZenIV.linux.org.uk> > Acked-by: Paolo Abeni <pabeni@redhat.com> > Tested-by: Sasha Levin <alexander.levin@verizon.com> > --- Oh well. Acked-by: Eric Dumazet <edumazet@google.com>
From: Paolo Abeni <pabeni@redhat.com> Date: Mon, 14 Aug 2017 21:31:38 +0200 > From: Al Viro <viro@ZenIV.linux.org.uk> > > copy_linear_skb() is broken; both of its callers actually > expect 'len' to be the amount we are trying to copy, > not the offset of the end. > Fix it keeping the meanings of arguments in sync with what the > callers (both of them) expect. > Also restore a saner behavior on EFAULT (i.e. preserving > the iov_iter position in case of failure): > > The commit fd851ba9caa9 ("udp: harden copy_linear_skb()") > avoids the more destructive effect of the buggy > copy_linear_skb(), e.g. no more invalid memory access, but > said function still behaves incorrectly: when peeking with > offset it can fail with EINVAL instead of copying the > appropriate amount of memory. > > Reported-by: Sasha Levin <alexander.levin@verizon.com> > Fixes: b65ac44674dd ("udp: try to avoid 2 cache miss on dequeue") > Fixes: fd851ba9caa9 ("udp: harden copy_linear_skb()") > Signed-off-by: Al Viro <viro@ZenIV.linux.org.uk> > Acked-by: Paolo Abeni <pabeni@redhat.com> > Tested-by: Sasha Levin <alexander.levin@verizon.com> > --- > This patch has been buried in a private email exchange for some > time. > I'm posting it on behalf of Al Viro, to avoid loosing this merge > window, since he is busy elsewhere. Applied, thanks.
diff --git a/include/net/udp.h b/include/net/udp.h index e9b1d1eacb59..586de4b811b5 100644 --- a/include/net/udp.h +++ b/include/net/udp.h @@ -366,14 +366,13 @@ static inline bool udp_skb_is_linear(struct sk_buff *skb) static inline int copy_linear_skb(struct sk_buff *skb, int len, int off, struct iov_iter *to) { - int n, copy = len - off; + int n; - if (copy < 0) - return -EINVAL; - n = copy_to_iter(skb->data + off, copy, to); - if (n == copy) + n = copy_to_iter(skb->data + off, len, to); + if (n == len) return 0; + iov_iter_revert(to, n); return -EFAULT; }