From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Dmitry V. Levin" Date: Mon, 11 Jan 2016 14:30:20 +0000 Subject: [RESEND PATCH] sparc64: fix incorrect sign extension in sys_sparc64_personality Message-Id: <20160111143019.GA29007@altlinux.org> List-Id: References: <20151226231327.GA18682@altlinux.org> In-Reply-To: <20151226231327.GA18682@altlinux.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: "David S. Miller" Cc: sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org 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 Cc: --- 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