From 1ce53e2c2ac069e7b3c400a427002a70deb4a916 Mon Sep 17 00:00:00 2001
From: Alejandro Colomar <alx.manpages@gmail.com>
Date: Sat, 28 Nov 2020 13:39:46 +0100
Subject: [PATCH] futex: Change utime parameter to be 'const ... *'
Git-commit: 1ce53e2c2ac069e7b3c400a427002a70deb4a916
Patch-mainline: v5.12-rc1
References: git-fixes
futex(2) says that 'utime' is a pointer to 'const'. The implementation
doesn't use 'const'; however, it _never_ modifies the contents of utime.
- futex() either uses 'utime' as a pointer to struct or as a 'u32'.
- In case it's used as a 'u32', it makes a copy of it, and of course it is
not dereferenced.
- In case it's used as a 'struct __kernel_timespec __user *', the pointer
is not dereferenced inside the futex() definition, and it is only passed
to a function: get_timespec64(), which accepts a 'const struct
__kernel_timespec __user *'.
[ tglx: Make the same change to the compat syscall and fixup the prototypes. ]
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201128123945.4592-1-alx.manpages@gmail.com
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
---
include/linux/syscalls.h | 8 ++++----
kernel/futex.c | 6 +++---
2 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index f3929aff39cf..5cb74edd9a4f 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -583,11 +583,11 @@ asmlinkage long sys_unshare(unsigned long unshare_flags);
/* kernel/futex.c */
asmlinkage long sys_futex(u32 __user *uaddr, int op, u32 val,
- struct __kernel_timespec __user *utime, u32 __user *uaddr2,
- u32 val3);
+ const struct __kernel_timespec __user *utime,
+ u32 __user *uaddr2, u32 val3);
asmlinkage long sys_futex_time32(u32 __user *uaddr, int op, u32 val,
- struct old_timespec32 __user *utime, u32 __user *uaddr2,
- u32 val3);
+ const struct old_timespec32 __user *utime,
+ u32 __user *uaddr2, u32 val3);
asmlinkage long sys_get_robust_list(int pid,
struct robust_list_head __user * __user *head_ptr,
size_t __user *len_ptr);
diff --git a/kernel/futex.c b/kernel/futex.c
index c47d1015d759..d0775aab8da9 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -3790,8 +3790,8 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
- struct __kernel_timespec __user *, utime, u32 __user *, uaddr2,
- u32, val3)
+ const struct __kernel_timespec __user *, utime,
+ u32 __user *, uaddr2, u32, val3)
{
struct timespec64 ts;
ktime_t t, *tp = NULL;
@@ -3986,7 +3986,7 @@ COMPAT_SYSCALL_DEFINE3(get_robust_list, int, pid,
#ifdef CONFIG_COMPAT_32BIT_TIME
SYSCALL_DEFINE6(futex_time32, u32 __user *, uaddr, int, op, u32, val,
- struct old_timespec32 __user *, utime, u32 __user *, uaddr2,
+ const struct old_timespec32 __user *, utime, u32 __user *, uaddr2,
u32, val3)
{
struct timespec64 ts;
--
2.26.2