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Commit 168bfeef authored by Andrew Morton's avatar Andrew Morton Committed by Borislav Petkov
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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: default avatarDenis Kirjanov <kirjanov@gmail.com>
Cc: stable@vger.kernel.org
Cc: Doug Thompson <dougthompson@xmission.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarBorislav Petkov <borislav.petkov@amd.com>
parent 6f0c0580

drivers/edac/amd64_edac.c

+4 −7
Original line number Diff line number Diff line
@@ -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;