On Tue, 6 Nov 2012 17:13:00 +0800 majianpeng <majianpeng@xxxxxxxxx> wrote:
> If read_seqretry returned true and bbp was changed, it will write
> invalid address which can cause some serious problem.
>
> This bug was introduced by commit v3.0-rc7-130-g2699b67.
> So fix is suitable for 3.0.y thru 3.6.y.
>
> Reported-by: zhuwenfeng@xxxxxxxxxxx
> Tested-by: zhuwenfeng@xxxxxxxxxxx
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Jianpeng Ma <majianpeng@xxxxxxxxx>
> ---
> drivers/md/md.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 9ab768a..d63aa78 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -1805,15 +1805,15 @@ static void super_1_sync(struct mddev *mddev, struct md_rdev *rdev)
> md_error(mddev, rdev);
> else {
> struct badblocks *bb = &rdev->badblocks;
> - u64 *bbp = (u64 *)page_address(rdev->bb_page);
> u64 *p = bb->page;
> sb->feature_map |= cpu_to_le32(MD_FEATURE_BAD_BLOCKS);
> if (bb->changed) {
> unsigned seq;
> + u64 *bbp;
>
> retry:
> + bbp = (u64 *)page_address(rdev->bb_page);
> seq = read_seqbegin(&bb->lock);
> -
> memset(bbp, 0xff, PAGE_SIZE);
>
> for (i = 0 ; i < bb->count ; i++) {
No.
The contents of the page might change, but it is always the same page, so it
always has the same address, so "bbp" is guaranteed to be stable.
NeilBrown
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