offset_to_stripe() returns the stripe number (in type unsigned int) from an offset (in type uint64_t) by the following calculation, do_div(offset, d->stripe_size); For large capacity backing device (e.g. 18TB) with small stripe size (e.g. 4KB), the result is 4831838208 and exceeds UINT_MAX. The actual returned value which caller receives is 536870912, due to the overflow. This patch changes offset_to_stripe()'s return value from type unsigned int to long int, and returns -EINVAL if do_div() result >= current max stripe number bcache_device->nr_stripes. Because nr_stripe is in type unsigned int, the non-negative return value will never overflow. Reported-by: Ken Raeburn <raeburn@xxxxxxxxxx> Signed-off-by: Coly Li <colyli@xxxxxxx> Link: https://bugzilla.redhat.com/show_bug.cgi?id=1783075 Cc: stable@xxxxxxxxxxxxxxx --- drivers/md/bcache/writeback.c | 14 +++++++++----- drivers/md/bcache/writeback.h | 18 ++++++++++++++++-- 2 files changed, 25 insertions(+), 7 deletions(-) diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c index 5397a2c5d6cc..2de6e9260443 100644 --- a/drivers/md/bcache/writeback.c +++ b/drivers/md/bcache/writeback.c @@ -521,15 +521,19 @@ void bcache_dev_sectors_dirty_add(struct cache_set *c, unsigned int inode, uint64_t offset, int nr_sectors) { struct bcache_device *d = c->devices[inode]; - unsigned int stripe_offset, stripe, sectors_dirty; + unsigned int stripe_offset, sectors_dirty; + long stripe; if (!d) return; + stripe = offset_to_stripe(d, offset); + if (stripe < 0) + return; + if (UUID_FLASH_ONLY(&c->uuids[inode])) atomic_long_add(nr_sectors, &c->flash_dev_dirty_sectors); - stripe = offset_to_stripe(d, offset); stripe_offset = offset & (d->stripe_size - 1); while (nr_sectors) { @@ -569,12 +573,12 @@ static bool dirty_pred(struct keybuf *buf, struct bkey *k) static void refill_full_stripes(struct cached_dev *dc) { struct keybuf *buf = &dc->writeback_keys; - unsigned int start_stripe, stripe, next_stripe; + unsigned int start_stripe, next_stripe; + long stripe; bool wrapped = false; stripe = offset_to_stripe(&dc->disk, KEY_OFFSET(&buf->last_scanned)); - - if (stripe >= dc->disk.nr_stripes) + if (stripe < 0) stripe = 0; start_stripe = stripe; diff --git a/drivers/md/bcache/writeback.h b/drivers/md/bcache/writeback.h index b029843ce5b6..8550b984954a 100644 --- a/drivers/md/bcache/writeback.h +++ b/drivers/md/bcache/writeback.h @@ -52,10 +52,21 @@ static inline uint64_t bcache_dev_sectors_dirty(struct bcache_device *d) return ret; } -static inline unsigned int offset_to_stripe(struct bcache_device *d, +static inline long offset_to_stripe(struct bcache_device *d, uint64_t offset) { do_div(offset, d->stripe_size); + + if (unlikely(offset >= d->nr_stripes)) { + pr_err("Invalid stripe %llu (>= nr_stripes %u).\n", + offset, d->nr_stripes); + return -EINVAL; + } + + /* + * Here offset is definitly smaller than UINT_MAX, + * return it as long int will never overflow. + */ return offset; } @@ -63,7 +74,10 @@ static inline bool bcache_dev_stripe_dirty(struct cached_dev *dc, uint64_t offset, unsigned int nr_sectors) { - unsigned int stripe = offset_to_stripe(&dc->disk, offset); + long stripe = offset_to_stripe(&dc->disk, offset); + + if (stripe < 0) + return false; while (1) { if (atomic_read(dc->disk.stripe_sectors_dirty + stripe)) -- 2.26.2
