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amd64_edac:__amd64_set_scrub_rate(): avoid overindexing scrubrates[] 

If none of the elements in scrubrates[] matches, this loop will cause
__amd64_set_scrub_rate() to incorrectly use the n+1th element.

As the function is designed to use the final scrubrates[] element in the
case of no match, we can fix this bug by simply terminating the array
search at the n-1th element.

Boris: this code is fragile anyway, see here why:
http://marc.info/?l=linux-kernel&m=135102834131236&w=2

It will be rewritten more robustly soonish.

Reported-by: Denis Kirjanov <kirjanov@gmail.com>
Cc: stable@vger.kernel.org
Cc: Doug Thompson <dougthompson@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
This commit is contained in:
Andrew Morton 2012-10-23 14:09:39 -07:00 committed by Borislav Petkov
parent 6f0c0580b7
commit 168bfeef7b
1 changed files with 4 additions and 7 deletions
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11
drivers/edac/amd64_edac.c
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@ -170,8 +170,11 @@ static int __amd64_set_scrub_rate(struct pci_dev *ctl, u32 new_bw, u32 min_rate)
* memory controller and apply to register. Search for the first
* bandwidth entry that is greater or equal than the setting requested
* and program that. If at last entry, turn off DRAM scrubbing.
*
* If no suitable bandwidth is found, turn off DRAM scrubbing entirely
* by falling back to the last element in scrubrates[].
*/
for (i = 0; i < ARRAY_SIZE(scrubrates); i++) {
for (i = 0; i < ARRAY_SIZE(scrubrates) - 1; i++) {
/*
* skip scrub rates which aren't recommended
* (see F10 BKDG, F3x58)
@ -181,12 +184,6 @@ static int __amd64_set_scrub_rate(struct pci_dev *ctl, u32 new_bw, u32 min_rate)
if (scrubrates[i].bandwidth <= new_bw)
break;
/*
* if no suitable bandwidth found, turn off DRAM scrubbing
* entirely by falling back to the last element in the
* scrubrates array.
*/
}
scrubval = scrubrates[i].scrubval;