From 57ea1d3d9da0429c94cf3ccdaba2f8f9aee355cc Mon Sep 17 00:00:00 2001 From: "Martin K. Petersen" Date: Tue, 4 Apr 2017 10:42:30 -0400 Subject: [PATCH] scsi: sd: Fix capacity calculation with 32-bit sector_t commit 7c856152cb92f8eee2df29ef325a1b1f43161aff upstream. We previously made sure that the reported disk capacity was less than 0xffffffff blocks when the kernel was not compiled with large sector_t support (CONFIG_LBDAF). However, this check assumed that the capacity was reported in units of 512 bytes. Add a sanity check function to ensure that we only enable disks if the entire reported capacity can be expressed in terms of sector_t. Reported-by: Steve Magnani Cc: Bart Van Assche Reviewed-by: Bart Van Assche Signed-off-by: Martin K. Petersen [bwh: Backported to 3.2: use integer literal instead of U32_MAX] Signed-off-by: Ben Hutchings --- drivers/scsi/sd.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 614f2cd24b7f..6cbe2eb5326d 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -1648,6 +1648,22 @@ static void read_capacity_error(struct scsi_disk *sdkp, struct scsi_device *sdp, #define READ_CAPACITY_RETRIES_ON_RESET 10 +/* + * Ensure that we don't overflow sector_t when CONFIG_LBDAF is not set + * and the reported logical block size is bigger than 512 bytes. Note + * that last_sector is a u64 and therefore logical_to_sectors() is not + * applicable. + */ +static bool sd_addressable_capacity(u64 lba, unsigned int sector_size) +{ + u64 last_sector = (lba + 1ULL) << (ilog2(sector_size) - 9); + + if (sizeof(sector_t) == 4 && last_sector > 0xffffffffULL) + return false; + + return true; +} + static int read_capacity_16(struct scsi_disk *sdkp, struct scsi_device *sdp, unsigned char *buffer) { @@ -1710,7 +1726,7 @@ static int read_capacity_16(struct scsi_disk *sdkp, struct scsi_device *sdp, sd_read_protection_type(sdkp, buffer); - if ((sizeof(sdkp->capacity) == 4) && (lba >= 0xffffffffULL)) { + if (!sd_addressable_capacity(lba, sector_size)) { sd_printk(KERN_ERR, sdkp, "Too big for this kernel. Use a " "kernel compiled with support for large block " "devices.\n"); @@ -1796,7 +1812,7 @@ static int read_capacity_10(struct scsi_disk *sdkp, struct scsi_device *sdp, return sector_size; } - if ((sizeof(sdkp->capacity) == 4) && (lba == 0xffffffff)) { + if (!sd_addressable_capacity(lba, sector_size)) { sd_printk(KERN_ERR, sdkp, "Too big for this kernel. Use a " "kernel compiled with support for large block " "devices.\n"); -- 2.39.2