From 5e75160f48785464f9213c6bc8c72b9372c5318b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= 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 --- 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++;