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badblocks: fix infinite loop due to incorrect rounding and overflow #1032

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badblocks: fix infinite loop due to incorrect rounding and overflow #1032

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40 changes: 32 additions & 8 deletions block/badblocks.c
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Original file line number Diff line number Diff line change
Expand Up @@ -853,15 +853,21 @@ static bool _badblocks_set(struct badblocks *bb, sector_t s, sector_t sectors,
/* Invalid sectors number */
return false;

if (s > ULLONG_MAX - sectors)
return false;

if (bb->shift) {
/* round the start down, and the end up */
sector_t next = s + sectors;

rounddown(s, 1 << bb->shift);
roundup(next, 1 << bb->shift);
s = round_down(s, 1 << bb->shift);
next = round_up(next, 1 << bb->shift);
sectors = next - s;
}

if (sectors == 0)
return false;

write_seqlock_irqsave(&bb->lock, flags);

bad.ack = acknowledged;
Expand Down Expand Up @@ -1061,6 +1067,9 @@ static bool _badblocks_clear(struct badblocks *bb, sector_t s, sector_t sectors)
/* Invalid sectors number */
return false;

if (s > ULLONG_MAX - sectors)
return false;

if (bb->shift) {
sector_t target;

Expand All @@ -1071,11 +1080,17 @@ static bool _badblocks_clear(struct badblocks *bb, sector_t s, sector_t sectors)
* isn't than to think a block is not bad when it is.
*/
target = s + sectors;
roundup(s, 1 << bb->shift);
rounddown(target, 1 << bb->shift);
sectors = target - s;
s = round_up(s, 1 << bb->shift);
target = round_down(target, 1 << bb->shift);
if (target < s)
sectors = 0;
else
sectors = target - s;
}

if (sectors == 0)
return false;

write_seqlock_irq(&bb->lock);

bad.ack = true;
Expand Down Expand Up @@ -1303,13 +1318,22 @@ int badblocks_check(struct badblocks *bb, sector_t s, sector_t sectors,

WARN_ON(bb->shift < 0 || sectors == 0);

if (s > ULLONG_MAX - sectors)
return -EINVAL;

if (bb->shift > 0) {
/* round the start down, and the end up */
sector_t target = s + sectors;

rounddown(s, 1 << bb->shift);
roundup(target, 1 << bb->shift);
sectors = target - s;
s = round_down(s, 1 << bb->shift);
target = round_up(target, 1 << bb->shift);
if (target < s)
sectors = 0;
else
sectors = target - s;

if (sectors == 0)
return 0;
}

retry:
Expand Down