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Subject[PATCH v2] powerpc/signal32: Use fault_in_pages_readable() to prefault user context
Date
Use fault_in_pages_readable() to prefault user context
instead of open coding

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
v2: using sizeof(*ctx) as size of ctx instead of 1

arch/powerpc/kernel/signal_32.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index 492f03451877..4a9e4d6d555b 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -25,6 +25,7 @@
#include <linux/errno.h>
#include <linux/elf.h>
#include <linux/ptrace.h>
+#include <linux/pagemap.h>
#include <linux/ratelimit.h>
#ifdef CONFIG_PPC64
#include <linux/syscalls.h>
@@ -1045,7 +1046,6 @@ long sys_swapcontext(struct ucontext __user *old_ctx,
struct ucontext __user *new_ctx,
int ctx_size, int r6, int r7, int r8, struct pt_regs *regs)
{
- unsigned char tmp __maybe_unused;
int ctx_has_vsx_region = 0;

#ifdef CONFIG_PPC64
@@ -1109,9 +1109,8 @@ long sys_swapcontext(struct ucontext __user *old_ctx,
}
if (new_ctx == NULL)
return 0;
- if (!access_ok(VERIFY_READ, new_ctx, ctx_size)
- || __get_user(tmp, (u8 __user *) new_ctx)
- || __get_user(tmp, (u8 __user *) new_ctx + ctx_size - 1))
+ if (!access_ok(VERIFY_READ, new_ctx, ctx_size) ||
+ fault_in_pages_readable((u8 __user *)new_ctx, ctx_size))
return -EFAULT;

/*
@@ -1231,7 +1230,6 @@ int sys_debug_setcontext(struct ucontext __user *ctx,
{
struct sig_dbg_op op;
int i;
- unsigned char tmp __maybe_unused;
unsigned long new_msr = regs->msr;
#ifdef CONFIG_PPC_ADV_DEBUG_REGS
unsigned long new_dbcr0 = current->thread.debug.dbcr0;
@@ -1287,9 +1285,8 @@ int sys_debug_setcontext(struct ucontext __user *ctx,
current->thread.debug.dbcr0 = new_dbcr0;
#endif

- if (!access_ok(VERIFY_READ, ctx, sizeof(*ctx))
- || __get_user(tmp, (u8 __user *) ctx)
- || __get_user(tmp, (u8 __user *) (ctx + 1) - 1))
+ if (!access_ok(VERIFY_READ, ctx, sizeof(*ctx)) ||
+ fault_in_pages_readable((u8 __user *)ctx, sizeof(*ctx)))
return -EFAULT;

/*
--
2.13.3
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