* [Qemu-devel] [PATCH] slirp: check data length while emulating ident function
@ 2019-01-11 8:19 P J P
2019-01-11 8:51 ` Marc-André Lureau
0 siblings, 1 reply; 5+ messages in thread
From: P J P @ 2019-01-11 8:19 UTC (permalink / raw)
To: QEMU Developers; +Cc: Samuel Thibault, Jason Wang, Kira, Prasad J Pandit
From: Prasad J Pandit <pjp@fedoraproject.org>
While emulating identification protocol, tcp_emu() does not check
available space in the 'sc_rcv->sb_data' buffer. It could lead to
heap buffer overflow issue. Add check to avoid it.
Reported-by: Kira <864786842@qq.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
---
slirp/tcp_subr.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/slirp/tcp_subr.c b/slirp/tcp_subr.c
index fa61349cbb..4415801fbb 100644
--- a/slirp/tcp_subr.c
+++ b/slirp/tcp_subr.c
@@ -635,6 +635,11 @@ tcp_emu(struct socket *so, struct mbuf *m)
socklen_t addrlen = sizeof(struct sockaddr_in);
struct sbuf *so_rcv = &so->so_rcv;
+ if (m->m_len > so_rcv->sb_datalen
+ - (so_rcv->sb_wptr - so_rcv->sb_data)) {
+ m_free(m);
+ return 0;
+ }
memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
so_rcv->sb_wptr += m->m_len;
so_rcv->sb_rptr += m->m_len;
--
2.20.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [Qemu-devel] [PATCH] slirp: check data length while emulating ident function
2019-01-11 8:19 [Qemu-devel] [PATCH] slirp: check data length while emulating ident function P J P
@ 2019-01-11 8:51 ` Marc-André Lureau
2019-01-11 9:18 ` P J P
0 siblings, 1 reply; 5+ messages in thread
From: Marc-André Lureau @ 2019-01-11 8:51 UTC (permalink / raw)
To: P J P; +Cc: QEMU Developers, Samuel Thibault, Jason Wang, Kira,
Prasad J Pandit
Hi
On Fri, Jan 11, 2019 at 12:31 PM P J P <ppandit@redhat.com> wrote:
>
> From: Prasad J Pandit <pjp@fedoraproject.org>
>
> While emulating identification protocol, tcp_emu() does not check
> available space in the 'sc_rcv->sb_data' buffer. It could lead to
> heap buffer overflow issue. Add check to avoid it.
>
> Reported-by: Kira <864786842@qq.com>
> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
> ---
> slirp/tcp_subr.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/slirp/tcp_subr.c b/slirp/tcp_subr.c
> index fa61349cbb..4415801fbb 100644
> --- a/slirp/tcp_subr.c
> +++ b/slirp/tcp_subr.c
> @@ -635,6 +635,11 @@ tcp_emu(struct socket *so, struct mbuf *m)
> socklen_t addrlen = sizeof(struct sockaddr_in);
> struct sbuf *so_rcv = &so->so_rcv;
>
> + if (m->m_len > so_rcv->sb_datalen
> + - (so_rcv->sb_wptr - so_rcv->sb_data)) {
> + m_free(m);
> + return 0;
> + }
Check looks correct, it should probably return 1.
Is there a reproducer?
> memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
> so_rcv->sb_wptr += m->m_len;
> so_rcv->sb_rptr += m->m_len;
> --
> 2.20.1
>
>
--
Marc-André Lureau
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [Qemu-devel] [PATCH] slirp: check data length while emulating ident function
2019-01-11 8:51 ` Marc-André Lureau
@ 2019-01-11 9:18 ` P J P
2019-01-11 11:23 ` Marc-André Lureau
0 siblings, 1 reply; 5+ messages in thread
From: P J P @ 2019-01-11 9:18 UTC (permalink / raw)
To: Marc-André Lureau; +Cc: QEMU Developers, Samuel Thibault, Jason Wang, Kira
+-- On Fri, 11 Jan 2019, Marc-André Lureau wrote --+
| > + if (m->m_len > so_rcv->sb_datalen
| > + - (so_rcv->sb_wptr - so_rcv->sb_data)) {
| > + m_free(m);
| > + return 0;
| > + }
|
| Check looks correct, it should probably return 1.
Function comment says return 1 if 'm' is valid and should be appended via
sbappend(). Not sure if unprocessed 'm' should go to sbappend().
| Is there a reproducer?
Yes, I have one.
Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
47AF CE69 3A90 54AA 9045 1053 DD13 3D32 FE5B 041F
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [Qemu-devel] [PATCH] slirp: check data length while emulating ident function
2019-01-11 9:18 ` P J P
@ 2019-01-11 11:23 ` Marc-André Lureau
2019-01-13 18:08 ` P J P
0 siblings, 1 reply; 5+ messages in thread
From: Marc-André Lureau @ 2019-01-11 11:23 UTC (permalink / raw)
To: P J P; +Cc: QEMU Developers, Samuel Thibault, Jason Wang, Kira
Hi
On Fri, Jan 11, 2019 at 1:18 PM P J P <ppandit@redhat.com> wrote:
>
> +-- On Fri, 11 Jan 2019, Marc-André Lureau wrote --+
> | > + if (m->m_len > so_rcv->sb_datalen
> | > + - (so_rcv->sb_wptr - so_rcv->sb_data)) {
> | > + m_free(m);
> | > + return 0;
> | > + }
> |
> | Check looks correct, it should probably return 1.
>
> Function comment says return 1 if 'm' is valid and should be appended via
> sbappend(). Not sure if unprocessed 'm' should go to sbappend().
If you look at the rest of the function, many similar error cases return 1.
> | Is there a reproducer?
>
> Yes, I have one.
Ok, could you add it to the commit message ? :)
>
> Thank you.
> --
> Prasad J Pandit / Red Hat Product Security Team
> 47AF CE69 3A90 54AA 9045 1053 DD13 3D32 FE5B 041F
--
Marc-André Lureau
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [Qemu-devel] [PATCH] slirp: check data length while emulating ident function
2019-01-11 11:23 ` Marc-André Lureau
@ 2019-01-13 18:08 ` P J P
0 siblings, 0 replies; 5+ messages in thread
From: P J P @ 2019-01-13 18:08 UTC (permalink / raw)
To: Marc-André Lureau; +Cc: QEMU Developers, Samuel Thibault, Jason Wang, Kira
+-- On Fri, 11 Jan 2019, Marc-André Lureau wrote --+
| > | Check looks correct, it should probably return 1.
| >
| > Function comment says return 1 if 'm' is valid and should be appended via
| > sbappend(). Not sure if unprocessed 'm' should go to sbappend().
|
| If you look at the rest of the function, many similar error cases return 1.
True, not sure if that's right in this case. Nonetheless, I have sent a
revised patch to return 1.
| Ok, could you add it to the commit message ? :)
No, I'm afraid not.
Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
47AF CE69 3A90 54AA 9045 1053 DD13 3D32 FE5B 041F
^ permalink raw reply [flat|nested] 5+ messages in thread
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2019-01-11 8:19 [Qemu-devel] [PATCH] slirp: check data length while emulating ident function P J P
2019-01-11 8:51 ` Marc-André Lureau
2019-01-11 9:18 ` P J P
2019-01-11 11:23 ` Marc-André Lureau
2019-01-13 18:08 ` P J P
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