EeePC notworking

29.10.2010 21:31

Here's something that may interest owners of EeePCs running Linux and is not getting much attention as far as I can see.

The atl1e driver for Atheros L1E (wired) Ethernet interface occasionally corrupts network data. To my knowledge this is the chip used on at least EeePC 901 and 1000. I'm seeing this bug in kernel 2.6.26 and there are reports of it in the latest versions as well.

What this means is that transferring any data through the wired network over a protocol that does not do its own checksumming is unsafe. This includes NFS, HTTP, FTP and so on and using these protocols may leave you with corrupted data. SSH (scp, rsync) is safe, since it performs cryptographic checks and will drop the connection if it encounters an error ("Corrupted MAC on input").

What is known so far is that corruption occurs in 128 byte blocks and that it's highly likely it only happens once per boot or sleep/resume cycle. It appears that the error happens during the transfer of packets from hardware's receive buffers to the kernel. Since this chip does its own TCP checksum check this means that the check is done before the corruption occurs and therefore does not protect you.

Here is an example of corrupted data:

--- correct-data	2010-10-22 22:20:33.000000000 +0200
+++ corrupt-data	2010-10-22 22:20:33.000000000 +0200
@@ -14,15 +14,15 @@
 000000d0  d0 d1 d2 d3 d4 d5 d6 d7  d8 d9 da db dc dd de df  |................|
 000000e0  e0 e1 e2 e3 e4 e5 e6 e7  e8 e9 ea eb ec ed ee ef  |................|
 000000f0  f0 f1 f2 f3 f4 f5 f6 f7  f8 f9 fa fb fc fd fe ff  |................|
-00000100  00 01 02 03 04 05 06 07  08 09 0a 0b 0c 0d 0e 0f  |................|
-00000110  10 11 12 13 14 15 16 17  18 19 1a 1b 1c 1d 1e 1f  |................|
-00000120  20 21 22 23 24 25 26 27  28 29 2a 2b 2c 2d 2e 2f  | !"#$%&'()*+,-./|
-00000130  30 31 32 33 34 35 36 37  38 39 3a 3b 3c 3d 3e 3f  |0123456789:;<=>?|
-00000140  40 41 42 43 44 45 46 47  48 49 4a 4b 4c 4d 4e 4f  |@ABCDEFGHIJKLMNO|
-00000150  50 51 52 53 54 55 56 57  58 59 5a 5b 5c 5d 5e 5f  |PQRSTUVWXYZ[\]^_|
-00000160  60 61 62 63 64 65 66 67  68 69 6a 6b 6c 6d 6e 6f  |`abcdefghijklmno|
-00000170  70 71 72 73 74 75 76 77  78 79 7a 7b 7c 7d 7e 7f  |pqrstuvwxyz{|}~.|
-00000180  80 81 82 83 84 85 86 87  88 89 8a 8b 8c 8d 8e 8f  |................|
+00000100  00 01 02 03 04 05 06 07  08 09 0a 0b 0c 0d 9e 9f  |................|
+00000110  a0 a1 a2 a3 a4 a5 a6 a7  a8 a9 aa ab ac ad ae af  |................|
+00000120  b0 b1 b2 b3 b4 b5 b6 b7  b8 b9 ba bb bc bd be bf  |................|
+00000130  c0 c1 c2 c3 c4 c5 c6 c7  c8 c9 ca cb cc cd ce cf  |................|
+00000140  d0 d1 d2 d3 d4 d5 d6 d7  d8 d9 da db dc dd de df  |................|
+00000150  e0 e1 e2 e3 e4 e5 e6 e7  e8 e9 ea eb ec ed ee ef  |................|
+00000160  f0 f1 f2 f3 f4 f5 f6 f7  f8 f9 fa fb fc fd fe ff  |................|
+00000170  00 01 02 03 04 05 06 07  08 09 0a 0b 0c 0d 0e 0f  |................|
+00000180  10 11 12 13 14 15 16 17  18 19 1a 1b 1c 1d 8e 8f  |................|
 00000190  90 91 92 93 94 95 96 97  98 99 9a 9b 9c 9d 9e 9f  |................|
 000001a0  a0 a1 a2 a3 a4 a5 a6 a7  a8 a9 aa ab ac ad ae af  |................|
 000001b0  b0 b1 b2 b3 b4 b5 b6 b7  b8 b9 ba bb bc bd be bf  |................|

More technical details are in the Linux kernel Bugzilla, bug #12282.

Posted by Tomaž | Categories: Code

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