linux-kernel - [PATCH] fix broken aliasing checks for MAP

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Date:	Sat, 05 Dec 2009 20:15:50 +0000
From:	Al Viro <viro@....linux.org.uk>
To:	linux-arch@...r.kernel.org
Cc:	lethal@...ux-sh.org, ralf@...ux-mips.org, rmk@....linux.org.uk,
	davem@...emloft.net, torvalds@...ux-foundation.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] fix broken aliasing checks for MAP_FIXED on sparc32,
 mips, arm and sh


We want addr - (pgoff << PAGE_SHIFT) consistently coloured...
BTW, sparc64 is correct, sparc32 isn't.

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
[On top of the mmap/mremap series, but should apply to mainline modulo line
numbers shift]

 arch/arm/mm/mmap.c               |    3 ++-
 arch/mips/kernel/syscall.c       |    3 ++-
 arch/sh/mm/mmap.c                |    3 ++-
 arch/sparc/kernel/sys_sparc_32.c |    3 ++-
 4 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
index 2b79964..f5abc51 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -54,7 +54,8 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	 * We enforce the MAP_FIXED case.
 	 */
 	if (flags & MAP_FIXED) {
-		if (aliasing && flags & MAP_SHARED && addr & (SHMLBA - 1))
+		if (aliasing && flags & MAP_SHARED &&
+		    (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
 			return -EINVAL;
 		return addr;
 	}
diff --git a/arch/mips/kernel/syscall.c b/arch/mips/kernel/syscall.c
index c25b2e7..3f7f466 100644
--- a/arch/mips/kernel/syscall.c
+++ b/arch/mips/kernel/syscall.c
@@ -93,7 +93,8 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 		 * We do not accept a shared mapping if it would violate
 		 * cache aliasing constraints.
 		 */
-		if ((flags & MAP_SHARED) && (addr & shm_align_mask))
+		if ((flags & MAP_SHARED) &&
+		    ((addr - (pgoff << PAGE_SHIFT)) & shm_align_mask))
 			return -EINVAL;
 		return addr;
 	}
diff --git a/arch/sh/mm/mmap.c b/arch/sh/mm/mmap.c
index d2984fa..afeb710 100644
--- a/arch/sh/mm/mmap.c
+++ b/arch/sh/mm/mmap.c
@@ -54,7 +54,8 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 		/* We do not accept a shared mapping if it would violate
 		 * cache aliasing constraints.
 		 */
-		if ((flags & MAP_SHARED) && (addr & shm_align_mask))
+		if ((flags & MAP_SHARED) &&
+		    ((addr - (pgoff << PAGE_SHIFT)) & shm_align_mask))
 			return -EINVAL;
 		return addr;
 	}
diff --git a/arch/sparc/kernel/sys_sparc_32.c b/arch/sparc/kernel/sys_sparc_32.c
index 997bdd0..3a82e65 100644
--- a/arch/sparc/kernel/sys_sparc_32.c
+++ b/arch/sparc/kernel/sys_sparc_32.c
@@ -45,7 +45,8 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi
 		/* We do not accept a shared mapping if it would violate
 		 * cache aliasing constraints.
 		 */
-		if ((flags & MAP_SHARED) && (addr & (SHMLBA - 1)))
+		if ((flags & MAP_SHARED) &&
+		    ((addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)))
 			return -EINVAL;
 		return addr;
 	}
-- 
1.5.6.5

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