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![Linus Torvalds](/assets/img/avatar_default.png)
The getaffinity() system call uses 'cpumask_size()' to decide how big the CPU mask is - so far so good. It is indeed the allocation size of a cpumask. But the code also assumes that the whole allocation is initialized without actually doing so itself. That's wrong, because we might have fixed-size allocations (making copying and clearing more efficient), but not all of it is then necessarily used if 'nr_cpu_ids' is smaller. Having checked other users of 'cpumask_size()', they all seem to be ok, either using it purely for the allocation size, or explicitly zeroing the cpumask before using the size in bytes to copy it. See for example the ublk_ctrl_get_queue_affinity() function that uses the proper 'zalloc_cpumask_var()' to make sure that the whole mask is cleared, whether the storage is on the stack or if it was an external allocation. Fix this by just zeroing the allocation before using it. Do the same for the compat version of sched_getaffinity(), which had the same logic. Also, for consistency, make sched_getaffinity() use 'cpumask_bits()' to access the bits. For a cpumask_var_t, it ends up being a pointer to the same data either way, but it's just a good idea to treat it like you would a 'cpumask_t'. The compat case already did that. Reported-by: Ryan Roberts <ryan.roberts@arm.com> Link: https://lore.kernel.org/lkml/7d026744-6bd6-6827-0471-b5e8eae0be3f@arm.com/ Cc: Yury Norov <yury.norov@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
271 lines
6.8 KiB
C
271 lines
6.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* linux/kernel/compat.c
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*
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* Kernel compatibililty routines for e.g. 32 bit syscall support
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* on 64 bit kernels.
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*
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* Copyright (C) 2002-2003 Stephen Rothwell, IBM Corporation
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*/
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#include <linux/linkage.h>
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#include <linux/compat.h>
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#include <linux/errno.h>
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#include <linux/time.h>
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#include <linux/signal.h>
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#include <linux/sched.h> /* for MAX_SCHEDULE_TIMEOUT */
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#include <linux/syscalls.h>
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#include <linux/unistd.h>
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#include <linux/security.h>
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#include <linux/export.h>
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#include <linux/migrate.h>
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#include <linux/posix-timers.h>
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#include <linux/times.h>
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#include <linux/ptrace.h>
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#include <linux/gfp.h>
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#include <linux/uaccess.h>
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#ifdef __ARCH_WANT_SYS_SIGPROCMASK
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/*
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* sys_sigprocmask SIG_SETMASK sets the first (compat) word of the
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* blocked set of signals to the supplied signal set
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*/
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static inline void compat_sig_setmask(sigset_t *blocked, compat_sigset_word set)
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{
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memcpy(blocked->sig, &set, sizeof(set));
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}
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COMPAT_SYSCALL_DEFINE3(sigprocmask, int, how,
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compat_old_sigset_t __user *, nset,
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compat_old_sigset_t __user *, oset)
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{
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old_sigset_t old_set, new_set;
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sigset_t new_blocked;
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old_set = current->blocked.sig[0];
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if (nset) {
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if (get_user(new_set, nset))
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return -EFAULT;
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new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
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new_blocked = current->blocked;
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switch (how) {
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case SIG_BLOCK:
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sigaddsetmask(&new_blocked, new_set);
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break;
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case SIG_UNBLOCK:
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sigdelsetmask(&new_blocked, new_set);
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break;
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case SIG_SETMASK:
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compat_sig_setmask(&new_blocked, new_set);
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break;
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default:
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return -EINVAL;
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}
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set_current_blocked(&new_blocked);
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}
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if (oset) {
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if (put_user(old_set, oset))
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return -EFAULT;
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}
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return 0;
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}
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#endif
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int put_compat_rusage(const struct rusage *r, struct compat_rusage __user *ru)
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{
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struct compat_rusage r32;
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memset(&r32, 0, sizeof(r32));
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r32.ru_utime.tv_sec = r->ru_utime.tv_sec;
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r32.ru_utime.tv_usec = r->ru_utime.tv_usec;
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r32.ru_stime.tv_sec = r->ru_stime.tv_sec;
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r32.ru_stime.tv_usec = r->ru_stime.tv_usec;
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r32.ru_maxrss = r->ru_maxrss;
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r32.ru_ixrss = r->ru_ixrss;
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r32.ru_idrss = r->ru_idrss;
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r32.ru_isrss = r->ru_isrss;
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r32.ru_minflt = r->ru_minflt;
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r32.ru_majflt = r->ru_majflt;
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r32.ru_nswap = r->ru_nswap;
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r32.ru_inblock = r->ru_inblock;
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r32.ru_oublock = r->ru_oublock;
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r32.ru_msgsnd = r->ru_msgsnd;
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r32.ru_msgrcv = r->ru_msgrcv;
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r32.ru_nsignals = r->ru_nsignals;
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r32.ru_nvcsw = r->ru_nvcsw;
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r32.ru_nivcsw = r->ru_nivcsw;
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if (copy_to_user(ru, &r32, sizeof(r32)))
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return -EFAULT;
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return 0;
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}
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static int compat_get_user_cpu_mask(compat_ulong_t __user *user_mask_ptr,
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unsigned len, struct cpumask *new_mask)
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{
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unsigned long *k;
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if (len < cpumask_size())
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memset(new_mask, 0, cpumask_size());
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else if (len > cpumask_size())
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len = cpumask_size();
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k = cpumask_bits(new_mask);
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return compat_get_bitmap(k, user_mask_ptr, len * 8);
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}
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COMPAT_SYSCALL_DEFINE3(sched_setaffinity, compat_pid_t, pid,
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unsigned int, len,
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compat_ulong_t __user *, user_mask_ptr)
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{
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cpumask_var_t new_mask;
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int retval;
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if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
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return -ENOMEM;
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retval = compat_get_user_cpu_mask(user_mask_ptr, len, new_mask);
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if (retval)
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goto out;
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retval = sched_setaffinity(pid, new_mask);
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out:
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free_cpumask_var(new_mask);
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return retval;
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}
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COMPAT_SYSCALL_DEFINE3(sched_getaffinity, compat_pid_t, pid, unsigned int, len,
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compat_ulong_t __user *, user_mask_ptr)
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{
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int ret;
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cpumask_var_t mask;
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if ((len * BITS_PER_BYTE) < nr_cpu_ids)
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return -EINVAL;
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if (len & (sizeof(compat_ulong_t)-1))
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return -EINVAL;
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if (!zalloc_cpumask_var(&mask, GFP_KERNEL))
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return -ENOMEM;
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ret = sched_getaffinity(pid, mask);
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if (ret == 0) {
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unsigned int retlen = min(len, cpumask_size());
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if (compat_put_bitmap(user_mask_ptr, cpumask_bits(mask), retlen * 8))
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ret = -EFAULT;
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else
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ret = retlen;
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}
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free_cpumask_var(mask);
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return ret;
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}
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/*
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* We currently only need the following fields from the sigevent
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* structure: sigev_value, sigev_signo, sig_notify and (sometimes
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* sigev_notify_thread_id). The others are handled in user mode.
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* We also assume that copying sigev_value.sival_int is sufficient
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* to keep all the bits of sigev_value.sival_ptr intact.
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*/
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int get_compat_sigevent(struct sigevent *event,
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const struct compat_sigevent __user *u_event)
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{
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memset(event, 0, sizeof(*event));
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return (!access_ok(u_event, sizeof(*u_event)) ||
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__get_user(event->sigev_value.sival_int,
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&u_event->sigev_value.sival_int) ||
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__get_user(event->sigev_signo, &u_event->sigev_signo) ||
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__get_user(event->sigev_notify, &u_event->sigev_notify) ||
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__get_user(event->sigev_notify_thread_id,
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&u_event->sigev_notify_thread_id))
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? -EFAULT : 0;
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}
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long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask,
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unsigned long bitmap_size)
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{
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unsigned long nr_compat_longs;
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/* align bitmap up to nearest compat_long_t boundary */
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bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
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nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);
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if (!user_read_access_begin(umask, bitmap_size / 8))
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return -EFAULT;
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while (nr_compat_longs > 1) {
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compat_ulong_t l1, l2;
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unsafe_get_user(l1, umask++, Efault);
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unsafe_get_user(l2, umask++, Efault);
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*mask++ = ((unsigned long)l2 << BITS_PER_COMPAT_LONG) | l1;
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nr_compat_longs -= 2;
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}
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if (nr_compat_longs)
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unsafe_get_user(*mask, umask++, Efault);
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user_read_access_end();
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return 0;
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Efault:
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user_read_access_end();
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return -EFAULT;
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}
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long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask,
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unsigned long bitmap_size)
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{
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unsigned long nr_compat_longs;
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/* align bitmap up to nearest compat_long_t boundary */
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bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
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nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);
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if (!user_write_access_begin(umask, bitmap_size / 8))
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return -EFAULT;
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while (nr_compat_longs > 1) {
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unsigned long m = *mask++;
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unsafe_put_user((compat_ulong_t)m, umask++, Efault);
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unsafe_put_user(m >> BITS_PER_COMPAT_LONG, umask++, Efault);
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nr_compat_longs -= 2;
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}
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if (nr_compat_longs)
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unsafe_put_user((compat_ulong_t)*mask, umask++, Efault);
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user_write_access_end();
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return 0;
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Efault:
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user_write_access_end();
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return -EFAULT;
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}
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int
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get_compat_sigset(sigset_t *set, const compat_sigset_t __user *compat)
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{
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#ifdef __BIG_ENDIAN
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compat_sigset_t v;
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if (copy_from_user(&v, compat, sizeof(compat_sigset_t)))
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return -EFAULT;
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switch (_NSIG_WORDS) {
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case 4: set->sig[3] = v.sig[6] | (((long)v.sig[7]) << 32 );
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fallthrough;
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case 3: set->sig[2] = v.sig[4] | (((long)v.sig[5]) << 32 );
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fallthrough;
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case 2: set->sig[1] = v.sig[2] | (((long)v.sig[3]) << 32 );
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fallthrough;
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case 1: set->sig[0] = v.sig[0] | (((long)v.sig[1]) << 32 );
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}
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#else
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if (copy_from_user(set, compat, sizeof(compat_sigset_t)))
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return -EFAULT;
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#endif
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return 0;
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}
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EXPORT_SYMBOL_GPL(get_compat_sigset);
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