From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: [PATCH] powerpc/signal64: Don't opencode page prefaulting
Date: Tue, 7 Jul 2020 18:32:25 +0000 (UTC) [thread overview]
Message-ID: <810bd8840ef990a200f58c9dea9abe767ca02a3a.1594146723.git.christophe.leroy@csgroup.eu> (raw)
Instead of doing a __get_user() from the first and last location
into a tmp var which won't be used, use fault_in_pages_readable()
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/powerpc/kernel/signal_64.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index 55e5f76554da..c451c47538e1 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -21,6 +21,7 @@
#include <linux/ptrace.h>
#include <linux/ratelimit.h>
#include <linux/syscalls.h>
+#include <linux/pagemap.h>
#include <asm/sigcontext.h>
#include <asm/ucontext.h>
@@ -632,7 +633,6 @@ static long setup_trampoline(unsigned int syscall, unsigned int __user *tramp)
SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx,
struct ucontext __user *, new_ctx, long, ctx_size)
{
- unsigned char tmp;
sigset_t set;
unsigned long new_msr = 0;
int ctx_has_vsx_region = 0;
@@ -667,9 +667,8 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx,
}
if (new_ctx == NULL)
return 0;
- if (!access_ok(new_ctx, ctx_size)
- || __get_user(tmp, (u8 __user *) new_ctx)
- || __get_user(tmp, (u8 __user *) new_ctx + ctx_size - 1))
+ if (!access_ok(new_ctx, ctx_size) ||
+ fault_in_pages_readable((u8 __user *)new_ctx, ctx_size))
return -EFAULT;
/*
--
2.25.0
next reply other threads:[~2020-07-07 18:52 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-07 18:32 Christophe Leroy [this message]
2020-07-16 12:55 ` [PATCH] powerpc/signal64: Don't opencode page prefaulting Michael Ellerman
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