Commit-ID: 9af0c7a6fa860698d080481f24a342ba74b68982
Gitweb: http://git.kernel.org/tip/9af0c7a6fa860698d080481f24a342ba74b68982
Author: Ludwig Nussel <ludwig.nussel@xxxxxxx>
AuthorDate: Tue, 15 Nov 2011 14:46:46 -0800
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Mon, 5 Dec 2011 17:07:23 +0100
x86: Fix mmap random address range
On x86_32 casting the unsigned int result of get_random_int() to
long may result in a negative value. On x86_32 the range of
mmap_rnd() therefore was -255 to 255. The 32bit mode on x86_64
used 0 to 255 as intended.
The bug was introduced by 675a081 ("x86: unify mmap_{32|64}.c")
in January 2008.
Signed-off-by: Ludwig Nussel <ludwig.nussel@xxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: harvey.harrison@xxxxxxxxx
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Harvey Harrison <harvey.harrison@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/201111152246.pAFMklOB028527@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
arch/x86/mm/mmap.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index 4b5ba85..845df68 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -75,9 +75,9 @@ static unsigned long mmap_rnd(void)
*/
if (current->flags & PF_RANDOMIZE) {
if (mmap_is_ia32())
- rnd = (long)get_random_int() % (1<<8);
+ rnd = get_random_int() % (1<<8);
else
- rnd = (long)(get_random_int() % (1<<28));
+ rnd = get_random_int() % (1<<28);
}
return rnd << PAGE_SHIFT;
}
--
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