target: Avoid integer overflow in se_dev_align_max_sectors()

The expression (max_sectors * block_size) might overflow a u32
(indeed, since iblock sets max_hw_sectors to UINT_MAX, it is
guaranteed to overflow and end up with a much-too-small result in many
common cases).  Fix this by doing an equivalent calculation that
doesn't require multiplication.

While we're touching this code, avoid splitting a printk format across
two lines and use pr_info(...) instead of printk(KERN_INFO ...).

Signed-off-by: Roland Dreier <roland@purestorage.com>
Cc: stable@vger.kernel.org
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 9 insertions, 9 deletions

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index 8d774da16320..9abef9f8eb76 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -850,20 +850,20 @@ int se_dev_check_shutdown(struct se_device *dev)
 
 static u32 se_dev_align_max_sectors(u32 max_sectors, u32 block_size)
 {
-        u32 tmp, aligned_max_sectors;
+        u32 aligned_max_sectors;
+        u32 alignment;
         /*
          * Limit max_sectors to a PAGE_SIZE aligned value for modern
          * transport_allocate_data_tasks() operation.
          */
-        tmp = rounddown((max_sectors * block_size), PAGE_SIZE);
-        aligned_max_sectors = (tmp / block_size);
-        if (max_sectors != aligned_max_sectors) {
-                printk(KERN_INFO "Rounding down aligned max_sectors from %u"
-                                " to %u\n", max_sectors, aligned_max_sectors);
-                return aligned_max_sectors;
-        }
+        alignment = max(1ul, PAGE_SIZE / block_size);
+        aligned_max_sectors = rounddown(max_sectors, alignment);
+
+        if (max_sectors != aligned_max_sectors)
+                pr_info("Rounding down aligned max_sectors from %u to %u\n",
+                        max_sectors, aligned_max_sectors);
 
-        return max_sectors;
+        return aligned_max_sectors;
 }
 
 void se_dev_set_default_attribs(