[OpenWrt-Devel] [PATCH v2 0/3] libubox: Enhance robustness of blobmsg parsing

[Tobias Schramm]

Hi,

this patch set makes parsing of blobmsg messages more robust against
malformed data.

Previously blobmsg_parse would crash due to out of bounds reads when
provied with malformed blobs containing invalid blob length specifications.
I've introduced a _safe variant of all blobmsg_check_* methods that takes
an additional length argument that allows it to verify that all performed
reads will be inside the buffer containing the struct attr* to be checked.

Since we do already get the actual buffer length for free in a few places
(namely blobmsg_parse, blobmsg_parse_array) I've adjusted those methods to
use the _safe attribute checking variants.

I've not changed the semantics of the old, unsafe blobmsg_check_* functions
to include a compiler-level deprecation warning to ensure it does not break
builds of existing packages depending on libubox compiled with -Werror.

Best Regards,

Tobias Schramm

Changelog:
v2:
 - Add documentation to attribute checking methods in blobmsg.h

Tobias Schramm (3):
  Ensure blob_attr length check does not perform out of bounds reads
  Replace use of blobmsg_check_attr by blobmsg_check_attr_safe
  Add _safe variants for all attribute checking methods

 blob.h    |  4 ++--
 blobmsg.c | 42 ++++++++++++++++++++++++++++++--------
 blobmsg.h | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 95 insertions(+), 11 deletions(-)

-- 
2.19.1


_______________________________________________
openwrt-devel mailing list
openwrt-devel at lists.openwrt.org
https://lists.openwrt.org/mailman/listinfo/openwrt-devel