linux-kernel - [PATCH 2/3] lib/ioremap.c: avoid endless loop under ioremapping improper ranges

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Date:   Tue, 20 Sep 2016 13:49:56 +0800
From:   zijun_hu <zijun_hu@...o.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     zijun_hu@....com, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] lib/ioremap.c: avoid endless loop under ioremapping
 improper ranges

From: zijun_hu <zijun_hu@....com>

for ioremap_page_range(), endless loop maybe happen if either of parameter
addr and end is not page aligned, in order to fix this issue and hint range
parameter requirements BUG_ON() checkup are performed firstly

for ioremap_pte_range(), loop end condition is optimized due to lack of
relevant macro pte_addr_end()

Signed-off-by: zijun_hu <zijun_hu@....com>
---
 lib/ioremap.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/ioremap.c b/lib/ioremap.c
index 86c8911..0058cc8 100644
--- a/lib/ioremap.c
+++ b/lib/ioremap.c
@@ -64,7 +64,7 @@ static int ioremap_pte_range(pmd_t *pmd, unsigned long addr,
 		BUG_ON(!pte_none(*pte));
 		set_pte_at(&init_mm, addr, pte, pfn_pte(pfn, prot));
 		pfn++;
-	} while (pte++, addr += PAGE_SIZE, addr != end);
+	} while (pte++, addr += PAGE_SIZE, addr < end);
 	return 0;
 }
 
@@ -129,6 +129,7 @@ int ioremap_page_range(unsigned long addr,
 	int err;
 
 	BUG_ON(addr >= end);
+	BUG_ON(!PAGE_ALIGNED(addr | end));
 
 	start = addr;
 	phys_addr -= addr;
-- 
1.9.1