Messages in this thread | | | Date | Sun, 31 Aug 2008 00:04:23 +0400 | From | Cyrill Gorcunov <> | Subject | Re: buffer overflow in /proc/sys/sunrpc/transports |
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[Vegard Nossum - Sat, Aug 30, 2008 at 09:59:38PM +0200] | 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
yes, but this is just a side effect, if we fix main error - it should resolve this problem too. Did you try the fix I sent a few msgs ago? (I don't have sunrpc on my machine)
| | -- | "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 | - Cyrill -
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