[PATCH 2/8] mmc: fix max_discard_sectors

[Namjae Jeon]

From: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>

https://lkml.org/lkml/2013/4/1/292
As per above discussion, there is possibility that request's __data_len
field may overflow when max_discard_sectors greater than UINT_MAX >> 9

If multiple discard requests get merged, merged discard request's
size exceeds 4GB, there is possibility that merged discard request's
__data_len field may overflow.

This patch fixes this issue.

Reported-by: Max Filippov <jcmvbkbc@xxxxxxxxx>
Signed-off-by: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
Signed-off-by: Vivek Trivedi <t.vivek@xxxxxxxxxxx>
Tested-by: Max Filippov <jcmvbkbc@xxxxxxxxx>
---
 drivers/mmc/card/queue.c |    2 +-
 drivers/mmc/core/core.c  |    4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
index 9447a0e..54726b7 100644
--- a/drivers/mmc/card/queue.c
+++ b/drivers/mmc/card/queue.c
@@ -166,7 +166,7 @@ static void mmc_queue_setup_discard(struct request_queue *q,
 		return;
 
 	queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
-	q->limits.max_discard_sectors = max_discard;
+	blk_queue_max_discard_sectors(q, max_discard);
 	if (card->erased_byte == 0 && !mmc_can_discard(card))
 		q->limits.discard_zeroes_data = 1;
 	q->limits.discard_granularity = card->pref_erase << 9;
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 7b435a3..6ee530c 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -2058,7 +2058,7 @@ static unsigned int mmc_do_calc_max_discard(struct mmc_card *card,
 	if (card->erase_shift)
 		max_qty = UINT_MAX >> card->erase_shift;
 	else if (mmc_card_sd(card))
-		max_qty = UINT_MAX;
+		max_qty = UINT_MAX >> 9;
 	else
 		max_qty = UINT_MAX / card->erase_size;
 
@@ -2100,7 +2100,7 @@ unsigned int mmc_calc_max_discard(struct mmc_card *card)
 	unsigned int max_discard, max_trim;
 
 	if (!host->max_discard_to)
-		return UINT_MAX;
+		return UINT_MAX >> 9;
 
 	/*
 	 * Without erase_group_def set, MMC erase timeout depends on clock
-- 
1.7.9.5

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