[ 08/57] target: Avoid integer overflow in se_dev_align_max_sectors()
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2012-11-15 04:26:32
Also in:
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3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Roland Dreier <redacted> commit 3e03989b5868acf69a391a424dc71fcd6cc48167 upstream. 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 <redacted> Signed-off-by: Nicholas Bellinger <redacted> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- drivers/target/target_core_device.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-)
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c@@ -826,20 +826,20 @@ int se_dev_check_shutdown(struct se_devi 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); - return max_sectors; + if (max_sectors != aligned_max_sectors) + pr_info("Rounding down aligned max_sectors from %u to %u\n", + max_sectors, aligned_max_sectors); + + return aligned_max_sectors; } void se_dev_set_default_attribs(