[PATCH 2.6.32 10/55] sparc64: fix incorrect sign extension in sys_sparc64_personality

From: Willy Tarreau
Date: Fri Mar 04 2016 - 11:04:15 EST


2.6.32-longterm review patch. If anyone has any objections, please let me know.

------------------

From: "Dmitry V. Levin" <ldv@xxxxxxxxxxxx>

commit 525fd5a94e1be0776fa652df5c687697db508c91 upstream.

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@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Signed-off-by: Willy Tarreau <w@xxxxxx>
---
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 cfa0e19..74e579b 100644
--- a/arch/sparc/kernel/sys_sparc_64.c
+++ b/arch/sparc/kernel/sys_sparc_64.c
@@ -524,7 +524,7 @@ SYSCALL_DEFINE1(sparc64_newuname, struct new_utsname __user *, name)

SYSCALL_DEFINE1(sparc64_personality, unsigned long, personality)
{
- int ret;
+ long ret;

if (current->personality == PER_LINUX32 &&
personality == PER_LINUX)
--
1.7.12.2.21.g234cd45.dirty