[Bug 83391] Oops on sd_mod

bugzilla-daemon
2014-08-28T07:55:26Z

--- Comment #2 from tomsun <tomsunchen@gmail.com> ---

static void sd_read_block_limits(struct scsi_disk *sdkp)
{
unsigned int sector_sz = sdkp->device->sector_size;
const int vpd_len = 32;
unsigned char *buffer = kmalloc(vpd_len, GFP_KERNEL);

if (!buffer ||
/* Block Limits VPD */
scsi_get_vpd_page(sdkp->device, 0xb0, buffer, vpd_len))
goto out;

blk_queue_io_min(sdkp->disk->queue,
get_unaligned_be16(&buffer[6]) * sector_sz);
blk_queue_io_opt(sdkp->disk->queue,
get_unaligned_be32(&buffer[12]) * sector_sz);

if (buffer[3] == 0x3c) {
unsigned int lba_count, desc_count;

sdkp->max_ws_blocks =
(u32) min_not_zero(get_unaligned_be64(&buffer[36]),
(u64)0xffffffff);

if (!sdkp->lbpme)
goto out;

lba_count = get_unaligned_be32(&buffer[20]);
desc_count = get_unaligned_be32(&buffer[24]);

if (lba_count && desc_count)
sdkp->max_unmap_blocks = lba_count;

sdkp->unmap_granularity = get_unaligned_be32(&buffer[28]);

if (buffer[32] & 0x80)
sdkp->unmap_alignment =
get_unaligned_be32(&buffer[32]) & ~(1 << 31);

if (!sdkp->lbpvpd) { /* LBP VPD page not provided */

if (sdkp->max_unmap_blocks)
sd_config_discard(sdkp, SD_LBP_UNMAP);
else
sd_config_discard(sdkp, SD_LBP_WS16);

} else { /* LBP VPD page tells us what to use */

if (sdkp->lbpu && sdkp->max_unmap_blocks)
sd_config_discard(sdkp, SD_LBP_UNMAP);
else if (sdkp->lbpws)
sd_config_discard(sdkp, SD_LBP_WS16);
else if (sdkp->lbpws10)
sd_config_discard(sdkp, SD_LBP_WS10);
else
sd_config_discard(sdkp, SD_LBP_DISABLE);
}
}

out:
kfree(buffer);
}

first, the pointer of buffer is malloced 32 bytes memory, but the buffer be
misused as 64 bytes memory, ex. sdkp->max_ws_blocks =
(u32) min_not_zero(get_unaligned_be64(&buffer[36]),
(u64)0xffffffff);
I don't know why, is it the bug for this oops?

thank you very much~