Merge branch 'master' into staging

5 files changed, 572 insertions, 0 deletions

diff --git a/gnu/packages/patches/openssl-1.0.2-CVE-2018-0495.patch b/gnu/packages/patches/openssl-1.0.2-CVE-2018-0495.patch
new file mode 100644
index 0000000000..2d54ed03b9
--- /dev/null
+++ b/gnu/packages/patches/openssl-1.0.2-CVE-2018-0495.patch
@@ -0,0 +1,215 @@
+Fix CVE-2018-0495:
+
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-0495
+https://www.nccgroup.trust/us/our-research/technical-advisory-return-of-the-hidden-number-problem/
+
+Patch copied from upstream source repository:
+
+https://github.com/openssl/openssl/commit/949ff36623eafc3523a9f91784992965018ffb05
+
+From 949ff36623eafc3523a9f91784992965018ffb05 Mon Sep 17 00:00:00 2001
+From: Matt Caswell <matt@openssl.org>
+Date: Fri, 25 May 2018 12:10:13 +0100
+Subject: [PATCH] Add blinding to an ECDSA signature
+
+Keegan Ryan (NCC Group) has demonstrated a side channel attack on an
+ECDSA signature operation. During signing the signer calculates:
+
+s:= k^-1 * (m + r * priv_key) mod order
+
+The addition operation above provides a sufficient signal for a
+flush+reload attack to derive the private key given sufficient signature
+operations.
+
+As a mitigation (based on a suggestion from Keegan) we add blinding to
+the operation so that:
+
+s := k^-1 * blind^-1 (blind * m + blind * r * priv_key) mod order
+
+Since this attack is a localhost side channel only no CVE is assigned.
+
+Reviewed-by: Rich Salz <rsalz@openssl.org>
+---
+ CHANGES                  |  4 ++
+ crypto/ecdsa/ecdsatest.c |  9 ++++-
+ crypto/ecdsa/ecs_ossl.c  | 82 ++++++++++++++++++++++++++++++++--------
+ 3 files changed, 79 insertions(+), 16 deletions(-)
+
+diff --git a/crypto/ecdsa/ecdsatest.c b/crypto/ecdsa/ecdsatest.c
+index 0f301f86d9..a130fc9117 100644
+--- a/crypto/ecdsa/ecdsatest.c
++++ b/crypto/ecdsa/ecdsatest.c
+@@ -137,7 +137,7 @@ int restore_rand(void)
+         return 1;
+ }
+ 
+-static int fbytes_counter = 0;
++static int fbytes_counter = 0, use_fake = 0;
+ static const char *numbers[8] = {
+     "651056770906015076056810763456358567190100156695615665659",
+     "6140507067065001063065065565667405560006161556565665656654",
+@@ -158,6 +158,11 @@ int fbytes(unsigned char *buf, int num)
+     int ret;
+     BIGNUM *tmp = NULL;
+ 
++    if (use_fake == 0)
++        return old_rand->bytes(buf, num);
++
++    use_fake = 0;
++
+     if (fbytes_counter >= 8)
+         return 0;
+     tmp = BN_new();
+@@ -199,11 +204,13 @@ int x9_62_test_internal(BIO *out, int nid, const char *r_in, const char *s_in)
+     /* create the key */
+     if ((key = EC_KEY_new_by_curve_name(nid)) == NULL)
+         goto x962_int_err;
++    use_fake = 1;
+     if (!EC_KEY_generate_key(key))
+         goto x962_int_err;
+     BIO_printf(out, ".");
+     (void)BIO_flush(out);
+     /* create the signature */
++    use_fake = 1;
+     signature = ECDSA_do_sign(digest, 20, key);
+     if (signature == NULL)
+         goto x962_int_err;
+diff --git a/crypto/ecdsa/ecs_ossl.c b/crypto/ecdsa/ecs_ossl.c
+index 16d4f59b9b..1d37551803 100644
+--- a/crypto/ecdsa/ecs_ossl.c
++++ b/crypto/ecdsa/ecs_ossl.c
+@@ -252,6 +252,7 @@ static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dgst_len,
+ {
+     int ok = 0, i;
+     BIGNUM *kinv = NULL, *s, *m = NULL, *tmp = NULL, *order = NULL;
++    BIGNUM *blind = NULL, *blindm = NULL;
+     const BIGNUM *ckinv;
+     BN_CTX *ctx = NULL;
+     const EC_GROUP *group;
+@@ -269,14 +270,25 @@ static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dgst_len,
+     }
+ 
+     ret = ECDSA_SIG_new();
+-    if (!ret) {
++    if (ret == NULL) {
+         ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
+         return NULL;
+     }
+     s = ret->s;
+ 
+-    if ((ctx = BN_CTX_new()) == NULL || (order = BN_new()) == NULL ||
+-        (tmp = BN_new()) == NULL || (m = BN_new()) == NULL) {
++    ctx = BN_CTX_new();
++    if (ctx == NULL) {
++        ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
++        goto err;
++    }
++
++    BN_CTX_start(ctx);
++    order = BN_CTX_get(ctx);
++    tmp = BN_CTX_get(ctx);
++    m = BN_CTX_get(ctx);
++    blind = BN_CTX_get(ctx);
++    blindm = BN_CTX_get(ctx);
++    if (blindm == NULL) {
+         ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
+         goto err;
+     }
+@@ -315,26 +327,70 @@ static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dgst_len,
+             }
+         }
+ 
+-        if (!BN_mod_mul(tmp, priv_key, ret->r, order, ctx)) {
++        /*
++         * The normal signature calculation is:
++         *
++         *   s := k^-1 * (m + r * priv_key) mod order
++         *
++         * We will blind this to protect against side channel attacks
++         *
++         *   s := k^-1 * blind^-1 * (blind * m + blind * r * priv_key) mod order
++         */
++
++        /* Generate a blinding value */
++        do {
++            if (!BN_rand(blind, BN_num_bits(order) - 1, -1, 0))
++                goto err;
++        } while (BN_is_zero(blind));
++        BN_set_flags(blind, BN_FLG_CONSTTIME);
++        BN_set_flags(blindm, BN_FLG_CONSTTIME);
++        BN_set_flags(tmp, BN_FLG_CONSTTIME);
++
++        /* tmp := blind * priv_key * r mod order */
++        if (!BN_mod_mul(tmp, blind, priv_key, order, ctx)) {
++            ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
++            goto err;
++        }
++        if (!BN_mod_mul(tmp, tmp, ret->r, order, ctx)) {
++            ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
++            goto err;
++        }
++
++        /* blindm := blind * m mod order */
++        if (!BN_mod_mul(blindm, blind, m, order, ctx)) {
++            ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
++            goto err;
++        }
++
++        /* s : = (blind * priv_key * r) + (blind * m) mod order */
++        if (!BN_mod_add_quick(s, tmp, blindm, order)) {
++            ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
++            goto err;
++        }
++
++        /* s:= s * blind^-1 mod order */
++        if (BN_mod_inverse(blind, blind, order, ctx) == NULL) {
+             ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
+             goto err;
+         }
+-        if (!BN_mod_add_quick(s, tmp, m, order)) {
++        if (!BN_mod_mul(s, s, blind, order, ctx)) {
+             ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
+             goto err;
+         }
++
++        /* s := s * k^-1 mod order */
+         if (!BN_mod_mul(s, s, ckinv, order, ctx)) {
+             ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
+             goto err;
+         }
++
+         if (BN_is_zero(s)) {
+             /*
+              * if kinv and r have been supplied by the caller don't to
+              * generate new kinv and r values
+              */
+             if (in_kinv != NULL && in_r != NULL) {
+-                ECDSAerr(ECDSA_F_ECDSA_DO_SIGN,
+-                         ECDSA_R_NEED_NEW_SETUP_VALUES);
++                ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ECDSA_R_NEED_NEW_SETUP_VALUES);
+                 goto err;
+             }
+         } else
+@@ -349,15 +405,11 @@ static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dgst_len,
+         ECDSA_SIG_free(ret);
+         ret = NULL;
+     }
+-    if (ctx)
++    if (ctx != NULL) {
++        BN_CTX_end(ctx);
+         BN_CTX_free(ctx);
+-    if (m)
+-        BN_clear_free(m);
+-    if (tmp)
+-        BN_clear_free(tmp);
+-    if (order)
+-        BN_free(order);
+-    if (kinv)
++    }
++    if (kinv != NULL)
+         BN_clear_free(kinv);
+     return ret;
+ }
+-- 
+2.17.1
+
diff --git a/gnu/packages/patches/openssl-1.0.2-CVE-2018-0732.patch b/gnu/packages/patches/openssl-1.0.2-CVE-2018-0732.patch
new file mode 100644
index 0000000000..50b95306a5
--- /dev/null
+++ b/gnu/packages/patches/openssl-1.0.2-CVE-2018-0732.patch
@@ -0,0 +1,50 @@
+Fix CVE-2018-0732:
+
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-0732
+
+Patch copied from upstream source repository:
+
+https://github.com/openssl/openssl/commit/3984ef0b72831da8b3ece4745cac4f8575b19098
+
+From 3984ef0b72831da8b3ece4745cac4f8575b19098 Mon Sep 17 00:00:00 2001
+From: Guido Vranken <guidovranken@gmail.com>
+Date: Mon, 11 Jun 2018 19:38:54 +0200
+Subject: [PATCH] Reject excessively large primes in DH key generation.
+
+CVE-2018-0732
+
+Signed-off-by: Guido Vranken <guidovranken@gmail.com>
+
+(cherry picked from commit 91f7361f47b082ae61ffe1a7b17bb2adf213c7fe)
+
+Reviewed-by: Tim Hudson <tjh@openssl.org>
+Reviewed-by: Matt Caswell <matt@openssl.org>
+(Merged from https://github.com/openssl/openssl/pull/6457)
+---
+ crypto/dh/dh_key.c | 7 ++++++-
+ 1 file changed, 6 insertions(+), 1 deletion(-)
+
+diff --git a/crypto/dh/dh_key.c b/crypto/dh/dh_key.c
+index 387558f146..f235e0d682 100644
+--- a/crypto/dh/dh_key.c
++++ b/crypto/dh/dh_key.c
+@@ -130,10 +130,15 @@ static int generate_key(DH *dh)
+     int ok = 0;
+     int generate_new_key = 0;
+     unsigned l;
+-    BN_CTX *ctx;
++    BN_CTX *ctx = NULL;
+     BN_MONT_CTX *mont = NULL;
+     BIGNUM *pub_key = NULL, *priv_key = NULL;
+ 
++    if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) {
++        DHerr(DH_F_GENERATE_KEY, DH_R_MODULUS_TOO_LARGE);
++        return 0;
++    }
++
+     ctx = BN_CTX_new();
+     if (ctx == NULL)
+         goto err;
+-- 
+2.17.1
+
diff --git a/gnu/packages/patches/openssl-1.1.0-CVE-2018-0495.patch b/gnu/packages/patches/openssl-1.1.0-CVE-2018-0495.patch
new file mode 100644
index 0000000000..15dedbcbd0
--- /dev/null
+++ b/gnu/packages/patches/openssl-1.1.0-CVE-2018-0495.patch
@@ -0,0 +1,152 @@
+Fix CVE-2018-0495:
+
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-0495
+https://www.nccgroup.trust/us/our-research/technical-advisory-return-of-the-hidden-number-problem/
+
+Patch copied from upstream source repository:
+
+https://github.com/openssl/openssl/commit/0c27d793745c7837b13646302b6890a556b7017a
+
+From 0c27d793745c7837b13646302b6890a556b7017a Mon Sep 17 00:00:00 2001
+From: Matt Caswell <matt@openssl.org>
+Date: Fri, 25 May 2018 12:10:13 +0100
+Subject: [PATCH] Add blinding to an ECDSA signature
+
+Keegan Ryan (NCC Group) has demonstrated a side channel attack on an
+ECDSA signature operation. During signing the signer calculates:
+
+s:= k^-1 * (m + r * priv_key) mod order
+
+The addition operation above provides a sufficient signal for a
+flush+reload attack to derive the private key given sufficient signature
+operations.
+
+As a mitigation (based on a suggestion from Keegan) we add blinding to
+the operation so that:
+
+s := k^-1 * blind^-1 (blind * m + blind * r * priv_key) mod order
+
+Since this attack is a localhost side channel only no CVE is assigned.
+
+Reviewed-by: Rich Salz <rsalz@openssl.org>
+---
+ CHANGES                |  4 +++
+ crypto/ec/ecdsa_ossl.c | 70 +++++++++++++++++++++++++++++++++++++-----
+ 2 files changed, 67 insertions(+), 7 deletions(-)
+
+diff --git a/crypto/ec/ecdsa_ossl.c b/crypto/ec/ecdsa_ossl.c
+index 72e2f0f28b..449be0e92a 100644
+--- a/crypto/ec/ecdsa_ossl.c
++++ b/crypto/ec/ecdsa_ossl.c
+@@ -210,7 +210,8 @@ ECDSA_SIG *ossl_ecdsa_sign_sig(const unsigned char *dgst, int dgst_len,
+                                EC_KEY *eckey)
+ {
+     int ok = 0, i;
+-    BIGNUM *kinv = NULL, *s, *m = NULL, *tmp = NULL;
++    BIGNUM *kinv = NULL, *s, *m = NULL, *tmp = NULL, *blind = NULL;
++    BIGNUM *blindm = NULL;
+     const BIGNUM *order, *ckinv;
+     BN_CTX *ctx = NULL;
+     const EC_GROUP *group;
+@@ -243,8 +244,18 @@ ECDSA_SIG *ossl_ecdsa_sign_sig(const unsigned char *dgst, int dgst_len,
+     }
+     s = ret->s;
+ 
+-    if ((ctx = BN_CTX_new()) == NULL ||
+-        (tmp = BN_new()) == NULL || (m = BN_new()) == NULL) {
++    ctx = BN_CTX_secure_new();
++    if (ctx == NULL) {
++        ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
++        goto err;
++    }
++
++    BN_CTX_start(ctx);
++    tmp = BN_CTX_get(ctx);
++    m = BN_CTX_get(ctx);
++    blind = BN_CTX_get(ctx);
++    blindm = BN_CTX_get(ctx);
++    if (blindm == NULL) {
+         ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
+         goto err;
+     }
+@@ -284,18 +295,64 @@ ECDSA_SIG *ossl_ecdsa_sign_sig(const unsigned char *dgst, int dgst_len,
+             }
+         }
+ 
+-        if (!BN_mod_mul(tmp, priv_key, ret->r, order, ctx)) {
++        /*
++         * The normal signature calculation is:
++         *
++         *   s := k^-1 * (m + r * priv_key) mod order
++         *
++         * We will blind this to protect against side channel attacks
++         *
++         *   s := k^-1 * blind^-1 * (blind * m + blind * r * priv_key) mod order
++         */
++
++        /* Generate a blinding value */
++        do {
++            if (!BN_rand(blind, BN_num_bits(order) - 1, BN_RAND_TOP_ANY,
++                         BN_RAND_BOTTOM_ANY))
++                goto err;
++        } while (BN_is_zero(blind));
++        BN_set_flags(blind, BN_FLG_CONSTTIME);
++        BN_set_flags(blindm, BN_FLG_CONSTTIME);
++        BN_set_flags(tmp, BN_FLG_CONSTTIME);
++
++        /* tmp := blind * priv_key * r mod order */
++        if (!BN_mod_mul(tmp, blind, priv_key, order, ctx)) {
+             ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
+             goto err;
+         }
+-        if (!BN_mod_add_quick(s, tmp, m, order)) {
++        if (!BN_mod_mul(tmp, tmp, ret->r, order, ctx)) {
+             ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
+             goto err;
+         }
++
++        /* blindm := blind * m mod order */
++        if (!BN_mod_mul(blindm, blind, m, order, ctx)) {
++            ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
++            goto err;
++        }
++
++        /* s : = (blind * priv_key * r) + (blind * m) mod order */
++        if (!BN_mod_add_quick(s, tmp, blindm, order)) {
++            ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
++            goto err;
++        }
++
++        /* s:= s * blind^-1 mod order */
++        if (BN_mod_inverse(blind, blind, order, ctx) == NULL) {
++            ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
++            goto err;
++        }
++        if (!BN_mod_mul(s, s, blind, order, ctx)) {
++            ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
++            goto err;
++        }
++
++        /* s := s * k^-1 mod order */
+         if (!BN_mod_mul(s, s, ckinv, order, ctx)) {
+             ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
+             goto err;
+         }
++
+         if (BN_is_zero(s)) {
+             /*
+              * if kinv and r have been supplied by the caller don't to
+@@ -317,9 +374,8 @@ ECDSA_SIG *ossl_ecdsa_sign_sig(const unsigned char *dgst, int dgst_len,
+         ECDSA_SIG_free(ret);
+         ret = NULL;
+     }
++    BN_CTX_end(ctx);
+     BN_CTX_free(ctx);
+-    BN_clear_free(m);
+-    BN_clear_free(tmp);
+     BN_clear_free(kinv);
+     return ret;
+ }
+-- 
+2.17.1
+
diff --git a/gnu/packages/patches/openssl-1.1.0-CVE-2018-0732.patch b/gnu/packages/patches/openssl-1.1.0-CVE-2018-0732.patch
new file mode 100644
index 0000000000..dfea6e7d06
--- /dev/null
+++ b/gnu/packages/patches/openssl-1.1.0-CVE-2018-0732.patch
@@ -0,0 +1,50 @@
+Fix CVE-2018-0732:
+
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-0732
+
+Patch copied from upstream source repository:
+
+https://github.com/openssl/openssl/commit/ea7abeeabf92b7aca160bdd0208636d4da69f4f4
+
+From ea7abeeabf92b7aca160bdd0208636d4da69f4f4 Mon Sep 17 00:00:00 2001
+From: Guido Vranken <guidovranken@gmail.com>
+Date: Mon, 11 Jun 2018 19:38:54 +0200
+Subject: [PATCH] Reject excessively large primes in DH key generation.
+
+CVE-2018-0732
+
+Signed-off-by: Guido Vranken <guidovranken@gmail.com>
+
+(cherry picked from commit 91f7361f47b082ae61ffe1a7b17bb2adf213c7fe)
+
+Reviewed-by: Tim Hudson <tjh@openssl.org>
+Reviewed-by: Matt Caswell <matt@openssl.org>
+(Merged from https://github.com/openssl/openssl/pull/6457)
+---
+ crypto/dh/dh_key.c | 7 ++++++-
+ 1 file changed, 6 insertions(+), 1 deletion(-)
+
+diff --git a/crypto/dh/dh_key.c b/crypto/dh/dh_key.c
+index fce9ff47f3..58003d7087 100644
+--- a/crypto/dh/dh_key.c
++++ b/crypto/dh/dh_key.c
+@@ -78,10 +78,15 @@ static int generate_key(DH *dh)
+     int ok = 0;
+     int generate_new_key = 0;
+     unsigned l;
+-    BN_CTX *ctx;
++    BN_CTX *ctx = NULL;
+     BN_MONT_CTX *mont = NULL;
+     BIGNUM *pub_key = NULL, *priv_key = NULL;
+ 
++    if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) {
++        DHerr(DH_F_GENERATE_KEY, DH_R_MODULUS_TOO_LARGE);
++        return 0;
++    }
++
+     ctx = BN_CTX_new();
+     if (ctx == NULL)
+         goto err;
+-- 
+2.17.1
+
diff --git a/gnu/packages/patches/qemu-CVE-2018-11806.patch b/gnu/packages/patches/qemu-CVE-2018-11806.patch
new file mode 100644
index 0000000000..f021dfa747
--- /dev/null
+++ b/gnu/packages/patches/qemu-CVE-2018-11806.patch
@@ -0,0 +1,105 @@
+Fix CVE-2018-11806:
+
+https://lists.gnu.org/archive/html/qemu-devel/2018-06/msg01012.html
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-11806
+
+Patch copied from upstream source repository:
+
+https://git.qemu.org/?p=qemu.git;a=commitdiff;h=864036e251f54c99d31df124aad7f34f01f5344c
+
+From 864036e251f54c99d31df124aad7f34f01f5344c Mon Sep 17 00:00:00 2001
+From: Prasad J Pandit <pjp@fedoraproject.org>
+Date: Tue, 5 Jun 2018 23:38:35 +0530
+Subject: [PATCH] slirp: correct size computation while concatenating mbuf
+
+While reassembling incoming fragmented datagrams, 'm_cat' routine
+extends the 'mbuf' buffer, if it has insufficient room. It computes
+a wrong buffer size, which leads to overwriting adjacent heap buffer
+area. Correct this size computation in m_cat.
+
+Reported-by: ZDI Disclosures <zdi-disclosures@trendmicro.com>
+Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
+Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
+---
+ slirp/mbuf.c | 11 +++++------
+ slirp/mbuf.h |  8 +++-----
+ 2 files changed, 8 insertions(+), 11 deletions(-)
+
+diff --git a/slirp/mbuf.c b/slirp/mbuf.c
+index 5ff24559fd..18cbf759a7 100644
+--- a/slirp/mbuf.c
++++ b/slirp/mbuf.c
+@@ -138,7 +138,7 @@ m_cat(struct mbuf *m, struct mbuf *n)
+ 	 * If there's no room, realloc
+ 	 */
+ 	if (M_FREEROOM(m) < n->m_len)
+-		m_inc(m,m->m_size+MINCSIZE);
++		m_inc(m, m->m_len + n->m_len);
+ 
+ 	memcpy(m->m_data+m->m_len, n->m_data, n->m_len);
+ 	m->m_len += n->m_len;
+@@ -147,7 +147,7 @@ m_cat(struct mbuf *m, struct mbuf *n)
+ }
+ 
+ 
+-/* make m size bytes large */
++/* make m 'size' bytes large from m_data */
+ void
+ m_inc(struct mbuf *m, int size)
+ {
+@@ -158,12 +158,12 @@ m_inc(struct mbuf *m, int size)
+ 
+         if (m->m_flags & M_EXT) {
+ 	  datasize = m->m_data - m->m_ext;
+-          m->m_ext = g_realloc(m->m_ext, size);
++	  m->m_ext = g_realloc(m->m_ext, size + datasize);
+ 	  m->m_data = m->m_ext + datasize;
+         } else {
+ 	  char *dat;
+ 	  datasize = m->m_data - m->m_dat;
+-          dat = g_malloc(size);
++	  dat = g_malloc(size + datasize);
+ 	  memcpy(dat, m->m_dat, m->m_size);
+ 
+ 	  m->m_ext = dat;
+@@ -171,8 +171,7 @@ m_inc(struct mbuf *m, int size)
+ 	  m->m_flags |= M_EXT;
+         }
+ 
+-        m->m_size = size;
+-
++        m->m_size = size + datasize;
+ }
+ 
+ 
+diff --git a/slirp/mbuf.h b/slirp/mbuf.h
+index 893601ff9d..33b84485d6 100644
+--- a/slirp/mbuf.h
++++ b/slirp/mbuf.h
+@@ -33,8 +33,6 @@
+ #ifndef MBUF_H
+ #define MBUF_H
+ 
+-#define MINCSIZE 4096	/* Amount to increase mbuf if too small */
+-
+ /*
+  * Macros for type conversion
+  * mtod(m,t) -	convert mbuf pointer to data pointer of correct type
+@@ -72,11 +70,11 @@ struct mbuf {
+ 	struct	mbuf *m_prevpkt;	/* Flags aren't used in the output queue */
+ 	int	m_flags;		/* Misc flags */
+ 
+-	int	m_size;			/* Size of data */
++	int	m_size;			/* Size of mbuf, from m_dat or m_ext */
+ 	struct	socket *m_so;
+ 
+-	caddr_t	m_data;			/* Location of data */
+-	int	m_len;			/* Amount of data in this mbuf */
++	caddr_t	m_data;			/* Current location of data */
++	int	m_len;			/* Amount of data in this mbuf, from m_data */
+ 
+ 	Slirp *slirp;
+ 	bool	resolution_requested;
+-- 
+2.17.1
+