[OpenWrt-Devel] [PATCH 18.06] libubox: backport additional length-checking fixes
Baptiste Jonglez
baptiste at bitsofnetworks.org
Sat Jun 13 14:17:40 EDT 2020
From: Baptiste Jonglez <git at bitsofnetworks.org>
Fixes: FS#3177
Cc: Felix Fietkau <nbd at nbd.name>
Cc: Rafał Miłecki <rafal at milecki.pl>
Signed-off-by: Baptiste Jonglez <git at bitsofnetworks.org>
---
package/libs/libubox/Makefile | 2 +-
...s-iteration-in-the-blobmsg_check_arr.patch | 75 ++++++++++
...sg-fix-length-in-blobmsg_check_array.patch | 28 ++++
...-and-fix-name-length-checks-in-blobm.patch | 49 +++++++
...21-blobmsg-fix-missing-length-checks.patch | 138 ++++++++++++++++++
5 files changed, 291 insertions(+), 1 deletion(-)
create mode 100644 package/libs/libubox/patches/0018-blobmsg-fix-attrs-iteration-in-the-blobmsg_check_arr.patch
create mode 100644 package/libs/libubox/patches/0019-blobmsg-fix-length-in-blobmsg_check_array.patch
create mode 100644 package/libs/libubox/patches/0020-blobmsg-simplify-and-fix-name-length-checks-in-blobm.patch
create mode 100644 package/libs/libubox/patches/0021-blobmsg-fix-missing-length-checks.patch
diff --git a/package/libs/libubox/Makefile b/package/libs/libubox/Makefile
index e3a827c1ab..e4f1a6b503 100644
--- a/package/libs/libubox/Makefile
+++ b/package/libs/libubox/Makefile
@@ -1,7 +1,7 @@
include $(TOPDIR)/rules.mk
PKG_NAME:=libubox
-PKG_RELEASE=4
+PKG_RELEASE=5
PKG_SOURCE_PROTO:=git
PKG_SOURCE_URL=$(PROJECT_GIT)/project/libubox.git
diff --git a/package/libs/libubox/patches/0018-blobmsg-fix-attrs-iteration-in-the-blobmsg_check_arr.patch b/package/libs/libubox/patches/0018-blobmsg-fix-attrs-iteration-in-the-blobmsg_check_arr.patch
new file mode 100644
index 0000000000..2834e10ee3
--- /dev/null
+++ b/package/libs/libubox/patches/0018-blobmsg-fix-attrs-iteration-in-the-blobmsg_check_arr.patch
@@ -0,0 +1,75 @@
+From 5e75160f48785464f9213c6bc8c72b9372c5318b Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal at milecki.pl>
+Date: Sat, 23 May 2020 13:18:51 +0200
+Subject: [PATCH] blobmsg: fix attrs iteration in the blobmsg_check_array_len()
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Starting with 75e300aeec25 ("blobmsg: fix wrong payload len passed from
+blobmsg_check_array") blobmsg_check_array_len() gets *blob* length
+passed as argument. It cannot be used with __blobmsg_for_each_attr()
+which expects *data* length.
+
+Use blobmsg_for_each_attr() which calculates *data* length on its own.
+
+The same bug was already reported in the past and there was fix attempt
+in the commit cd75136b1342 ("blobmsg: fix wrong payload len passed from
+blobmsg_check_array"). That change made blobmsg_check_attr_len() calls
+fail however.
+
+This is hopefully the correct & complete fix:
+1. blobmsg_check_array_len() gets *blob* length
+2. It calls blobmsg_check_attr_len() which requires *blob* length
+3. It uses blobmsg_for_each_attr() which gets *data* length
+
+This fixes iterating over random memory treated as attrs. That was
+resulting in check failing randomly for totally correct blobs. It's
+critical e.g. for procd project with its instance_fill_array() failing
+and procd not starting services.
+
+Fixes: 75e300aeec25 ("blobmsg: fix wrong payload len passed from blobmsg_check_array")
+Signed-off-by: Rafał Miłecki <rafal at milecki.pl>
+---
+ blobmsg.c | 10 ++++++----
+ 1 file changed, 6 insertions(+), 4 deletions(-)
+
+diff --git a/blobmsg.c b/blobmsg.c
+index 8b9877d..59045e1 100644
+--- a/blobmsg.c
++++ b/blobmsg.c
+@@ -117,16 +117,18 @@ int blobmsg_check_array(const struct blob_attr *attr, int type)
+ return blobmsg_check_array_len(attr, type, blob_len(attr));
+ }
+
+-int blobmsg_check_array_len(const struct blob_attr *attr, int type, size_t len)
++int blobmsg_check_array_len(const struct blob_attr *attr, int type,
++ size_t blob_len)
+ {
+ struct blob_attr *cur;
++ size_t rem;
+ bool name;
+ int size = 0;
+
+ if (type > BLOBMSG_TYPE_LAST)
+ return -1;
+
+- if (!blobmsg_check_attr_len(attr, false, len))
++ if (!blobmsg_check_attr_len(attr, false, blob_len))
+ return -1;
+
+ switch (blobmsg_type(attr)) {
+@@ -140,11 +142,11 @@ int blobmsg_check_array_len(const struct blob_attr *attr, int type, size_t len)
+ return -1;
+ }
+
+- __blobmsg_for_each_attr(cur, attr, len) {
++ blobmsg_for_each_attr(cur, attr, rem) {
+ if (type != BLOBMSG_TYPE_UNSPEC && blobmsg_type(cur) != type)
+ return -1;
+
+- if (!blobmsg_check_attr_len(cur, name, len))
++ if (!blobmsg_check_attr_len(cur, name, rem))
+ return -1;
+
+ size++;
diff --git a/package/libs/libubox/patches/0019-blobmsg-fix-length-in-blobmsg_check_array.patch b/package/libs/libubox/patches/0019-blobmsg-fix-length-in-blobmsg_check_array.patch
new file mode 100644
index 0000000000..9db2fb4f9f
--- /dev/null
+++ b/package/libs/libubox/patches/0019-blobmsg-fix-length-in-blobmsg_check_array.patch
@@ -0,0 +1,28 @@
+From c2fc622b771f679e8f55060ac60cfe02b9a80995 Mon Sep 17 00:00:00 2001
+From: Felix Fietkau <nbd at nbd.name>
+Date: Mon, 25 May 2020 13:44:20 +0200
+Subject: [PATCH] blobmsg: fix length in blobmsg_check_array
+
+blobmsg_check_array_len expects the length of the full attribute buffer,
+not just the data length.
+Due to other missing length checks (fixed in the next commit), this did
+not show up as a test failure
+
+Signed-off-by: Felix Fietkau <nbd at nbd.name>
+---
+ blobmsg.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/blobmsg.c b/blobmsg.c
+index 59045e1..daaa9fc 100644
+--- a/blobmsg.c
++++ b/blobmsg.c
+@@ -114,7 +114,7 @@ bool blobmsg_check_attr_len(const struct blob_attr *attr, bool name, size_t len)
+
+ int blobmsg_check_array(const struct blob_attr *attr, int type)
+ {
+- return blobmsg_check_array_len(attr, type, blob_len(attr));
++ return blobmsg_check_array_len(attr, type, blob_raw_len(attr));
+ }
+
+ int blobmsg_check_array_len(const struct blob_attr *attr, int type,
diff --git a/package/libs/libubox/patches/0020-blobmsg-simplify-and-fix-name-length-checks-in-blobm.patch b/package/libs/libubox/patches/0020-blobmsg-simplify-and-fix-name-length-checks-in-blobm.patch
new file mode 100644
index 0000000000..a481208789
--- /dev/null
+++ b/package/libs/libubox/patches/0020-blobmsg-simplify-and-fix-name-length-checks-in-blobm.patch
@@ -0,0 +1,49 @@
+From 639c29d19717616b809d9a1e9042461ab8024370 Mon Sep 17 00:00:00 2001
+From: Felix Fietkau <nbd at nbd.name>
+Date: Mon, 25 May 2020 14:49:35 +0200
+Subject: [PATCH] blobmsg: simplify and fix name length checks in
+ blobmsg_check_name
+
+blobmsg_hdr_valid_namelen was omitted when name==false
+The blob_len vs blobmsg_namelen changes were not taking into account
+potential padding between name and data
+
+Signed-off-by: Felix Fietkau <nbd at nbd.name>
+---
+ blobmsg.c | 13 ++++---------
+ 1 file changed, 4 insertions(+), 9 deletions(-)
+
+diff --git a/blobmsg.c b/blobmsg.c
+index daaa9fc..308bef7 100644
+--- a/blobmsg.c
++++ b/blobmsg.c
+@@ -48,8 +48,8 @@ static bool blobmsg_hdr_valid_namelen(const struct blobmsg_hdr *hdr, size_t len)
+
+ static bool blobmsg_check_name(const struct blob_attr *attr, size_t len, bool name)
+ {
+- char *limit = (char *) attr + len;
+ const struct blobmsg_hdr *hdr;
++ uint16_t namelen;
+
+ hdr = blobmsg_hdr_from_blob(attr, len);
+ if (!hdr)
+@@ -58,16 +58,11 @@ static bool blobmsg_check_name(const struct blob_attr *attr, size_t len, bool na
+ if (name && !hdr->namelen)
+ return false;
+
+- if (name && !blobmsg_hdr_valid_namelen(hdr, len))
+- return false;
+-
+- if ((char *) hdr->name + blobmsg_namelen(hdr) + 1 > limit)
+- return false;
+-
+- if (blobmsg_namelen(hdr) > (blob_len(attr) - sizeof(struct blobmsg_hdr)))
++ namelen = blobmsg_namelen(hdr);
++ if (blob_len(attr) < (size_t)blobmsg_hdrlen(namelen))
+ return false;
+
+- if (hdr->name[blobmsg_namelen(hdr)] != 0)
++ if (hdr->name[namelen] != 0)
+ return false;
+
+ return true;
diff --git a/package/libs/libubox/patches/0021-blobmsg-fix-missing-length-checks.patch b/package/libs/libubox/patches/0021-blobmsg-fix-missing-length-checks.patch
new file mode 100644
index 0000000000..bfc440a329
--- /dev/null
+++ b/package/libs/libubox/patches/0021-blobmsg-fix-missing-length-checks.patch
@@ -0,0 +1,138 @@
+From 66195aee50424cbda0c2d858014e4cc58a2dc029 Mon Sep 17 00:00:00 2001
+From: Felix Fietkau <nbd at nbd.name>
+Date: Mon, 25 May 2020 12:40:04 +0200
+Subject: [PATCH] blobmsg: fix missing length checks
+
+blobmsg_check_attr_len was calling blobmsg_check_data for some, but not all
+attribute types. These checks was missing for arrays and tables.
+
+Additionally, the length check in blobmsg_check_data was a bit off, since
+it was comparing the blobmsg data length against the raw blob attr length.
+
+Fix this by checking the raw blob length against the buffer length in
+blobmsg_hdr_from_blob
+
+Signed-off-by: Felix Fietkau <nbd at nbd.name>
+---
+ blobmsg.c | 66 +++++++++++++++++--------------------------------------
+ 1 file changed, 20 insertions(+), 46 deletions(-)
+
+diff --git a/blobmsg.c b/blobmsg.c
+index 308bef7..7da4183 100644
+--- a/blobmsg.c
++++ b/blobmsg.c
+@@ -30,31 +30,18 @@ bool blobmsg_check_attr(const struct blob_attr *attr, bool name)
+ return blobmsg_check_attr_len(attr, name, blob_raw_len(attr));
+ }
+
+-static const struct blobmsg_hdr* blobmsg_hdr_from_blob(const struct blob_attr *attr, size_t len)
+-{
+- if (len < sizeof(struct blob_attr) + sizeof(struct blobmsg_hdr))
+- return NULL;
+-
+- return blob_data(attr);
+-}
+-
+-static bool blobmsg_hdr_valid_namelen(const struct blobmsg_hdr *hdr, size_t len)
+-{
+- if (len < sizeof(struct blob_attr) + sizeof(struct blobmsg_hdr) + blobmsg_namelen(hdr) + 1)
+- return false;
+-
+- return true;
+-}
+-
+-static bool blobmsg_check_name(const struct blob_attr *attr, size_t len, bool name)
++static bool blobmsg_check_name(const struct blob_attr *attr, bool name)
+ {
+ const struct blobmsg_hdr *hdr;
+ uint16_t namelen;
+
+- hdr = blobmsg_hdr_from_blob(attr, len);
+- if (!hdr)
++ if (!blob_is_extended(attr))
++ return !name;
++
++ if (blob_len(attr) < sizeof(struct blobmsg_hdr))
+ return false;
+
++ hdr = (const struct blobmsg_hdr *)blob_data(attr);
+ if (name && !hdr->namelen)
+ return false;
+
+@@ -68,29 +55,20 @@ static bool blobmsg_check_name(const struct blob_attr *attr, size_t len, bool na
+ return true;
+ }
+
+-static const char* blobmsg_check_data(const struct blob_attr *attr, size_t len, size_t *data_len)
+-{
+- char *limit = (char *) attr + len;
+- const char *data;
+-
+- *data_len = blobmsg_data_len(attr);
+- if (*data_len > blob_raw_len(attr))
+- return NULL;
+-
+- data = blobmsg_data(attr);
+- if (data + *data_len > limit)
+- return NULL;
+-
+- return data;
+-}
+-
+ bool blobmsg_check_attr_len(const struct blob_attr *attr, bool name, size_t len)
+ {
+ const char *data;
+ size_t data_len;
+ int id;
+
+- if (!blobmsg_check_name(attr, len, name))
++ if (len < sizeof(struct blob_attr))
++ return false;
++
++ data_len = blob_raw_len(attr);
++ if (data_len < sizeof(struct blob_attr) || data_len > len)
++ return false;
++
++ if (!blobmsg_check_name(attr, name))
+ return false;
+
+ id = blob_id(attr);
+@@ -100,9 +78,8 @@ bool blobmsg_check_attr_len(const struct blob_attr *attr, bool name, size_t len)
+ if (!blob_type[id])
+ return true;
+
+- data = blobmsg_check_data(attr, len, &data_len);
+- if (!data)
+- return false;
++ data = blobmsg_data(attr);
++ data_len = blobmsg_data_len(attr);
+
+ return blob_check_type(data, data_len, blob_type[id]);
+ }
+@@ -206,13 +183,13 @@ int blobmsg_parse(const struct blobmsg_policy *policy, int policy_len,
+ }
+
+ __blob_for_each_attr(attr, data, len) {
+- hdr = blobmsg_hdr_from_blob(attr, len);
+- if (!hdr)
++ if (!blobmsg_check_attr_len(attr, false, len))
+ return -1;
+
+- if (!blobmsg_hdr_valid_namelen(hdr, len))
+- return -1;
++ if (!blob_is_extended(attr))
++ continue;
+
++ hdr = blob_data(attr);
+ for (i = 0; i < policy_len; i++) {
+ if (!policy[i].name)
+ continue;
+@@ -224,9 +201,6 @@ int blobmsg_parse(const struct blobmsg_policy *policy, int policy_len,
+ if (blobmsg_namelen(hdr) != pslen[i])
+ continue;
+
+- if (!blobmsg_check_attr_len(attr, true, len))
+- return -1;
+-
+ if (tb[i])
+ continue;
--
2.26.2
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