File slirp-use-correct-size-while-emulating-I.patch of Package qemu

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File slirp-use-correct-size-while-emulating-I.patch of Package qemu

From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Thu, 9 Jan 2020 15:12:27 +0530
Subject: slirp: use correct size while emulating IRC commands

Git-commit: ce131029d6d4a405cb7d3ac6716d03e58fb4a5d9
References: bsc#1163018, CVE-2020-8608

While emulating IRC DCC commands, tcp_emu() uses 'mbuf' size
'm->m_size' to write DCC commands via snprintf(3). This may
lead to OOB write access, because 'bptr' points somewhere in
the middle of 'mbuf' buffer, not at the start. Use M_FREEROOM(m)
size to avoid OOB access.

Reported-by: Vishnu Dev TJ <vishnudevtj@gmail.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Message-Id: <20200109094228.79764-2-ppandit@redhat.com>
Signed-off-by: Bruce Rogers <brogers@suse.com>
---
 src/tcp_subr.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/slirp/src/tcp_subr.c b/slirp/src/tcp_subr.c
index d6dd133a9f7082dbc6fafdfa7e01..6cd181c9f2875528adab3f636aec 100644
--- a/slirp/src/tcp_subr.c
+++ b/slirp/src/tcp_subr.c
@@ -778,7 +778,8 @@ int tcp_emu(struct socket *so, struct mbuf *m)
                 return 1;
             }
             m->m_len = bptr - m->m_data; /* Adjust length */
-            m->m_len += snprintf(bptr, m->m_size, "DCC CHAT chat %lu %u%c\n",
+            m->m_len += snprintf(bptr, M_FREEROOM(m),
+                                 "DCC CHAT chat %lu %u%c\n",
                                  (unsigned long)ntohl(so->so_faddr.s_addr),
                                  ntohs(so->so_fport), 1);
         } else if (sscanf(bptr, "DCC SEND %256s %u %u %u", buff, &laddr, &lport,
@@ -788,8 +789,8 @@ int tcp_emu(struct socket *so, struct mbuf *m)
                 return 1;
             }
             m->m_len = bptr - m->m_data; /* Adjust length */
-            m->m_len +=
-                snprintf(bptr, m->m_size, "DCC SEND %s %lu %u %u%c\n", buff,
+            m->m_len += snprintf(bptr, M_FREEROOM(m),
+                         "DCC SEND %s %lu %u %u%c\n", buff,
                          (unsigned long)ntohl(so->so_faddr.s_addr),
                          ntohs(so->so_fport), n1, 1);
         } else if (sscanf(bptr, "DCC MOVE %256s %u %u %u", buff, &laddr, &lport,
@@ -799,8 +800,8 @@ int tcp_emu(struct socket *so, struct mbuf *m)
                 return 1;
             }
             m->m_len = bptr - m->m_data; /* Adjust length */
-            m->m_len +=
-                snprintf(bptr, m->m_size, "DCC MOVE %s %lu %u %u%c\n", buff,
+            m->m_len += snprintf(bptr, M_FREEROOM(m),
+                         "DCC MOVE %s %lu %u %u%c\n", buff,
                          (unsigned long)ntohl(so->so_faddr.s_addr),
                          ntohs(so->so_fport), n1, 1);
         }

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File slirp-use-correct-size-while-emulating-I.patch of Package qemu

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