From 718178f524b98bc920d74bc771aed823c8b81425 Mon Sep 17 00:00:00 2001 From: Maoyi Xie Date: Thu, 2 Jul 2026 16:27:45 +0800 Subject: [PATCH] memstick: ms_block: reject a card that reports too many blocks msb_ftl_initialize() computes the zone count from the card block count with no bound: msb->zone_count = msb->block_count / MS_BLOCKS_IN_ZONE; ... for (i = 0; i < msb->zone_count; i++) msb->free_block_count[i] = MS_BLOCKS_IN_ZONE; msb->block_count is a card value. msb_read_boot_blocks() reads number_of_blocks from the card boot page and byte swaps it. free_block_count is a fixed int[MS_MAX_ZONES]. MS_MAX_ZONES is 16, so the valid indices are 0 to 15. The init loop above indexes it by zone_count. msb_mark_block_used() and msb_mark_block_unused() index it by pba / MS_BLOCKS_IN_ZONE, for pba up to block_count - 1. A card may report up to 65535 blocks. A block_count above 8192 (MS_MAX_ZONES * MS_BLOCKS_IN_ZONE) lets the pba index reach 16. That writes past free_block_count[] and corrupts struct msb_data. A larger count runs the init loop past the end too. A real Memory Stick has at most 16 zones. So it has at most 8192 blocks. msb_ftl_initialize() now rejects a card that reports more than MS_MAX_ZONES * MS_BLOCKS_IN_ZONE blocks. Fixes: 0ab30494bc4f ("memstick: add support for legacy memorysticks") Cc: stable@vger.kernel.org Signed-off-by: Maoyi Xie Signed-off-by: Ulf Hansson --- drivers/memstick/core/ms_block.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/memstick/core/ms_block.c b/drivers/memstick/core/ms_block.c index a01fe313558e7..ce33907bfc242 100644 --- a/drivers/memstick/core/ms_block.c +++ b/drivers/memstick/core/ms_block.c @@ -1338,6 +1338,10 @@ static int msb_ftl_initialize(struct msb_data *msb) return 0; msb->zone_count = msb->block_count / MS_BLOCKS_IN_ZONE; + if (msb->block_count > MS_MAX_ZONES * MS_BLOCKS_IN_ZONE) { + pr_err("Too many blocks: %d\n", msb->block_count); + return -EINVAL; + } msb->logical_block_count = msb->zone_count * 496 - 2; msb->used_blocks_bitmap = bitmap_zalloc(msb->block_count, GFP_KERNEL); -- 2.47.3