lkml.org 
[lkml]   [2008]   [Aug]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: buffer overflow in /proc/sys/sunrpc/transports
On Sat, Aug 30, 2008 at 9:56 PM, Cyrill Gorcunov <gorcunov@gmail.com> wrote:
> | BTW, look at this:
> |
> | $ od -A x -t x1z /proc/sys/sunrpc/transports
> | 000000 74 63 70 20 31 30 34 38 35 37 36 0a 75 64 70 20 >tcp 1048576.udp <
> | 000010 33 32 37 36 38 0a 00 00 00 00 00 00 00 00 00 00 >32768...........<
> | 000020 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >................<
> | *
> | 0003e0 00 00 00 00 00 00 00 00 00 00 >..........<
> | 0003ea
> |
> | ...and:
> |
> | $ strace -e trace=read cat /proc/sys/sunrpc/transports > /dev/null
> | read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0@G\316E4\0\0\0"...,
> | 512) = 512
> | read(3, "tcp 1048576\nudp 32768\n\0\0\0\0\0\0\0\0\0\0"..., 4096) = 4074
> | read(3, "", 4096) = 0
> |
> | ...why does it have a huge return value? The output is only about 40
> | bytes... why add all the \0? Would your patch also fix this?
>
> I think it's from strace side - it pass 4096 zero'ed buffer.

"cat" passed buffer of size 4096, yes. But read() still returned 4074.
It should have returned 38 or so.

> At least I don't see additional issues from kernel side in buffer
> filling - except from svc_print_xprts() which walk over list.
> But I think sunpc guys should know details :)
> Will send short-fix patch soon :)

It looks like it's returning (sizeof(buffer) - x) where it really
should be returning x. Maybe it's this one that should be different?

*lenp -= len;


Vegard

--
"The animistic metaphor of the bug that maliciously sneaked in while
the programmer was not looking is intellectually dishonest as it
disguises that the error is the programmer's own creation."
-- E. W. Dijkstra, EWD1036


\
 
 \ /
  Last update: 2008-08-30 22:03    [W:0.054 / U:0.016 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site