[PATCH] powerpc/signal64: Don't opencode page prefaulting
From: Christophe Leroy <hidden>
Date: 2020-07-07 18:32:31
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 <redacted> --- 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