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[RESEND PATCH] sparc64: fix incorrect sign extension in sys_sparc64_personality

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Date: Sat Dec 26 22:35:13 2015 +0000

The value returned by sys_personality has type "long int".
It is saved to a variable of type "int", which is not a problem
yet because the type of task_struct->pesonality is "unsigned int".
The problem is the sign extension from "int" to "long int"
that happens on return from sys_sparc64_personality.

For example, a userspace call personality((unsigned) -EINVAL) will
result to any subsequent personality call, including absolutely
harmless read-only personality(0xffffffff) call, failing with
errno set to EINVAL.

Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Cc: <stable@vger.kernel.org>
---
 arch/sparc/kernel/sys_sparc_64.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c
index 30e7ddb..c690c8e 100644
--- a/arch/sparc/kernel/sys_sparc_64.c
+++ b/arch/sparc/kernel/sys_sparc_64.c
@@ -413,15 +413,15 @@ out:
 
 SYSCALL_DEFINE1(sparc64_personality, unsigned long, personality)
 {
-	int ret;
+	long ret;
 
 	if (personality(current->personality) == PER_LINUX32 &&
 	    personality(personality) == PER_LINUX)
 		personality |= PER_LINUX32;
 	ret = sys_personality(personality);
 	if (personality(ret) == PER_LINUX32)
 		ret &= ~PER_LINUX32;
 
 	return ret;
 }

-- 
ldv

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[RESEND PATCH] sparc64: fix incorrect sign extension in sys_sparc64_personality "Dmitry V. Levin" <ldv@altlinux.org> - 2016-01-11 15:40 +0100
  Re: [RESEND PATCH] sparc64: fix incorrect sign extension in  sys_sparc64_personality David Miller <davem@davemloft.net> - 2016-01-11 22:30 +0100

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