[PATCH] lib: Return error if an incomplete message was read

[Thomas Egerer]

If recvmsg indicates that the message read was truncated libnl retries
to read the complete message after increasing the message buffer. This
only works if the message flags MSG_PEEK | MSG_TRUNC are set. If
NL_MSG_PEEK is not enabled on the nl_sock structure, flags are left
empty and the rest of the truncated message is discarded, hence a
subsequent recvmsg returns the next message (in case of a multipart
message, the NLMSG_DONE) is read and returned.
This patch aborts message processing if the message was truncated and
teh NL_MSG_PEEK flags was not activated for the nl_sock structure.

Signed-off-by: Thomas Egerer <hakke_007 at gmx.de>
---
Hello *,

I recently discovered a flaw in your library when reading large amounts
of data (larger than the 4096 byte buffer) without the NL_MSG_PEEK flag
set on the nl-socket. In this case the whole message is discarded while
the code suggests a reread. Example code for reproduction can be found
in [1].

[1] http://pastebin.com/hB1SAPrX

 lib/nl.c | 7 +++++++
 1 file changed, 7 insertions(+)


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