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zlg
Retired Dev
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Joined: 11 Sep 2012
Posts: 49
Location: Earth

PostPosted: Thu Mar 12, 2015 12:21 am    Post subject: Rowhammer results thread Reply with quote

I searched the forums before posting, but months ago some research was done on RAM chips and they found that sometimes bits can flip when addresses are accessed in quick succession. (more details on http://rowhammer.com )

Google recently published a program to test one's RAM against the Rowhammer vulnerability[1] and they started a Google Group for people to discuss it. [2] Since I don't have (and refuse to get) a Google account, I figured I and other like-minded people could post results for their hardware so others can be informed.

When posting results, you'll need to indicate which make and model of RAM, the timings, and clock speed. People in the mailing list decided this command would be best on GNU/Linux, but the output for mine didn't give make and model:

Code:
dmidecode | grep "Memory Device" -A19


You'll need to emerge sys-apps/dmidecode for this if you haven't already.

When running rowhammer-test, let it sit for about an hour (or 1000 iterations or more). The longer the better. The program will keep going until it encounters a flipped bit. I ran it for a little over 1000 iterations and found it still running, which indicates that my RAM was AOK. I'll post my results in the next post.

Mods: If this is the wrong place, please move it instead of deleting it! It's the best place I could think of to post it.

[1]: https://github.com/google/rowhammer-test
[2]: https://groups.google.com/group/rowhammer-discuss/


Last edited by zlg on Thu Mar 12, 2015 12:29 am; edited 1 time in total
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zlg
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Joined: 11 Sep 2012
Posts: 49
Location: Earth

PostPosted: Thu Mar 12, 2015 12:28 am    Post subject: Reply with quote

Results for `dmidecode | grep "Memory Device" -A19`:

Code:

Memory Device
   Array Handle: 0x0034
   Error Information Handle: Not Provided
   Total Width: 64 bits
   Data Width: 64 bits
   Size: 4096 MB
   Form Factor: DIMM
   Set: None
   Locator: DIMM0
   Bank Locator: BANK0
   Type: Other
   Type Detail: Synchronous
   Speed: 1333 MHz
   Manufacturer: Manufacturer0
   Serial Number: SerNum0
   Asset Tag: AssetTagNum0
   Part Number: PartNum0

Handle 0x0037, DMI type 20, 19 bytes
Memory Device Mapped Address
   Starting Address: 0x00000000000
   Ending Address: 0x000FFFFFFFF
   Range Size: 4 GB
   Physical Device Handle: 0x0036
   Memory Array Mapped Address Handle: 0x0035
   Partition Row Position: 1

Handle 0x0038, DMI type 17, 27 bytes
Memory Device
   Array Handle: 0x0034
   Error Information Handle: Not Provided
   Total Width: 64 bits
   Data Width: 64 bits
   Size: 4096 MB
   Form Factor: DIMM
   Set: None
   Locator: DIMM1
   Bank Locator: BANK1
   Type: Other
   Type Detail: Synchronous
   Speed: 1333 MHz
   Manufacturer: Manufacturer1
   Serial Number: SerNum1
   Asset Tag: AssetTagNum1
   Part Number: PartNum1

Handle 0x0039, DMI type 20, 19 bytes
Memory Device Mapped Address
   Starting Address: 0x00100000000
   Ending Address: 0x001FFFFFFFF
   Range Size: 4 GB
   Physical Device Handle: 0x0038
   Memory Array Mapped Address Handle: 0x0035
   Partition Row Position: 1

Handle 0x003A, DMI type 17, 27 bytes
Memory Device
   Array Handle: 0x0034
   Error Information Handle: Not Provided
   Total Width: 64 bits
   Data Width: 64 bits
   Size: 4096 MB
   Form Factor: DIMM
   Set: None
   Locator: DIMM2
   Bank Locator: BANK2
   Type: Other
   Type Detail: Synchronous
   Speed: 1333 MHz
   Manufacturer: Manufacturer2
   Serial Number: SerNum2
   Asset Tag: AssetTagNum2
   Part Number: PartNum2

Handle 0x003B, DMI type 20, 19 bytes
Memory Device Mapped Address
   Starting Address: 0x00200000000
   Ending Address: 0x002FFFFFFFF
   Range Size: 4 GB
   Physical Device Handle: 0x003A
   Memory Array Mapped Address Handle: 0x0035
   Partition Row Position: 1

Handle 0x003C, DMI type 17, 27 bytes
Memory Device
   Array Handle: 0x0034
   Error Information Handle: Not Provided
   Total Width: 64 bits
   Data Width: 64 bits
   Size: 4096 MB
   Form Factor: DIMM
   Set: None
   Locator: DIMM3
   Bank Locator: BANK3
   Type: Other
   Type Detail: Synchronous
   Speed: 1333 MHz
   Manufacturer: Manufacturer3
   Serial Number: SerNum3
   Asset Tag: AssetTagNum3
   Part Number: PartNum3

Handle 0x003D, DMI type 20, 19 bytes
Memory Device Mapped Address
   Starting Address: 0x00300000000
   Ending Address: 0x003FFFFFFFF
   Range Size: 4 GB
   Physical Device Handle: 0x003C
   Memory Array Mapped Address Handle: 0x0035
   Partition Row Position: 1

Handle 0x003E, DMI type 32, 20 bytes
System Boot Information
   Status: No errors detected

Handle 0x003F, DMI type 127, 4 bytes
End Of Table


I'm using four G.SKILL Sniper 4 GB sticks, DDR3 1333 (PC3 10666). The timings are stock (9-9-9-24) and Cas latency is 9.

I ran 1001 iterations of rowhammer-test (about an hour's worth) and no errors were found. I'm not sure if product page links are allowed on here, so I will forego linking to the Newegg page.
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frostschutz
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Joined: 22 Feb 2005
Posts: 2971
Location: Germany

PostPosted: Thu Mar 12, 2015 3:56 pm    Post subject: Reply with quote

For me the test (which I ran in Initramfs) took at most 5 minutes to find a flipped bit (fffbfff). wow. :lol:

I'm not too concerned about it - as long as this kind of memory access does not happen normally and exploiting it is not too straightforward.

Regular memtest runs for hours without errors.

2x BLT8G3D1608DT1TX0 on a Haswell sytem...
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NeddySeagoon
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Joined: 05 Jul 2003
Posts: 44010
Location: 56N 3W

PostPosted: Thu Mar 12, 2015 6:10 pm    Post subject: Reply with quote

sporkbox,

There are only three or four manufactuers of RAM chips in the word.
RAM stick vendors buy parts made by these companies.
dmidecode, if in tells you anything, will tell who made your RAM sticks, not the silicon.

What we need to know is the silicon manufactuer, part number of the chips and maybe the date code on the chips.
You can only get this info by examining the chips, probably with an eye glass.

Bit flips in non ECC RAM may go undetected, unless they occur in instructions that the CPU is trying to execute.
Then results vary from an incorrect instruction being executed to an illegal instruction exception.
You will notice the latter as the process will be killed but the former is much more difficult to spot.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.
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