227 lines
6.9 KiB
C
227 lines
6.9 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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#include <linux/compat.h>
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#include <linux/uaccess.h>
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#include <linux/ptrace.h>
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/*
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* The compat_siginfo_t structure and handing code is very easy
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* to break in several ways. It must always be updated when new
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* updates are made to the main siginfo_t, and
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* copy_siginfo_to_user32() must be updated when the
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* (arch-independent) copy_siginfo_to_user() is updated.
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*
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* It is also easy to put a new member in the compat_siginfo_t
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* which has implicit alignment which can move internal structure
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* alignment around breaking the ABI. This can happen if you,
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* for instance, put a plain 64-bit value in there.
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*/
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static inline void signal_compat_build_tests(void)
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{
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int _sifields_offset = offsetof(compat_siginfo_t, _sifields);
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/*
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* If adding a new si_code, there is probably new data in
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* the siginfo. Make sure folks bumping the si_code
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* limits also have to look at this code. Make sure any
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* new fields are handled in copy_siginfo_to_user32()!
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*/
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BUILD_BUG_ON(NSIGILL != 8);
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BUILD_BUG_ON(NSIGFPE != 8);
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BUILD_BUG_ON(NSIGSEGV != 4);
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BUILD_BUG_ON(NSIGBUS != 5);
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BUILD_BUG_ON(NSIGTRAP != 4);
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BUILD_BUG_ON(NSIGCHLD != 6);
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BUILD_BUG_ON(NSIGSYS != 1);
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/* This is part of the ABI and can never change in size: */
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BUILD_BUG_ON(sizeof(compat_siginfo_t) != 128);
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/*
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* The offsets of all the (unioned) si_fields are fixed
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* in the ABI, of course. Make sure none of them ever
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* move and are always at the beginning:
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*/
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BUILD_BUG_ON(offsetof(compat_siginfo_t, _sifields) != 3 * sizeof(int));
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#define CHECK_CSI_OFFSET(name) BUILD_BUG_ON(_sifields_offset != offsetof(compat_siginfo_t, _sifields.name))
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/*
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* Ensure that the size of each si_field never changes.
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* If it does, it is a sign that the
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* copy_siginfo_to_user32() code below needs to updated
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* along with the size in the CHECK_SI_SIZE().
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*
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* We repeat this check for both the generic and compat
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* siginfos.
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*
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* Note: it is OK for these to grow as long as the whole
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* structure stays within the padding size (checked
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* above).
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*/
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#define CHECK_CSI_SIZE(name, size) BUILD_BUG_ON(size != sizeof(((compat_siginfo_t *)0)->_sifields.name))
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#define CHECK_SI_SIZE(name, size) BUILD_BUG_ON(size != sizeof(((siginfo_t *)0)->_sifields.name))
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CHECK_CSI_OFFSET(_kill);
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CHECK_CSI_SIZE (_kill, 2*sizeof(int));
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CHECK_SI_SIZE (_kill, 2*sizeof(int));
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CHECK_CSI_OFFSET(_timer);
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CHECK_CSI_SIZE (_timer, 5*sizeof(int));
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CHECK_SI_SIZE (_timer, 6*sizeof(int));
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CHECK_CSI_OFFSET(_rt);
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CHECK_CSI_SIZE (_rt, 3*sizeof(int));
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CHECK_SI_SIZE (_rt, 4*sizeof(int));
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CHECK_CSI_OFFSET(_sigchld);
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CHECK_CSI_SIZE (_sigchld, 5*sizeof(int));
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CHECK_SI_SIZE (_sigchld, 8*sizeof(int));
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CHECK_CSI_OFFSET(_sigchld_x32);
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CHECK_CSI_SIZE (_sigchld_x32, 7*sizeof(int));
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/* no _sigchld_x32 in the generic siginfo_t */
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CHECK_CSI_OFFSET(_sigfault);
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CHECK_CSI_SIZE (_sigfault, 4*sizeof(int));
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CHECK_SI_SIZE (_sigfault, 8*sizeof(int));
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CHECK_CSI_OFFSET(_sigpoll);
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CHECK_CSI_SIZE (_sigpoll, 2*sizeof(int));
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CHECK_SI_SIZE (_sigpoll, 4*sizeof(int));
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CHECK_CSI_OFFSET(_sigsys);
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CHECK_CSI_SIZE (_sigsys, 3*sizeof(int));
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CHECK_SI_SIZE (_sigsys, 4*sizeof(int));
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/* any new si_fields should be added here */
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}
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void sigaction_compat_abi(struct k_sigaction *act, struct k_sigaction *oact)
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{
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/* Don't leak in-kernel non-uapi flags to user-space */
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if (oact)
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oact->sa.sa_flags &= ~(SA_IA32_ABI | SA_X32_ABI);
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if (!act)
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return;
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/* Don't let flags to be set from userspace */
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act->sa.sa_flags &= ~(SA_IA32_ABI | SA_X32_ABI);
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if (in_ia32_syscall())
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act->sa.sa_flags |= SA_IA32_ABI;
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if (in_x32_syscall())
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act->sa.sa_flags |= SA_X32_ABI;
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}
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int __copy_siginfo_to_user32(compat_siginfo_t __user *to, const siginfo_t *from,
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bool x32_ABI)
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{
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int err = 0;
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signal_compat_build_tests();
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if (!access_ok(VERIFY_WRITE, to, sizeof(compat_siginfo_t)))
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return -EFAULT;
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put_user_try {
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/* If you change siginfo_t structure, please make sure that
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this code is fixed accordingly.
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It should never copy any pad contained in the structure
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to avoid security leaks, but must copy the generic
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3 ints plus the relevant union member. */
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put_user_ex(from->si_signo, &to->si_signo);
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put_user_ex(from->si_errno, &to->si_errno);
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put_user_ex(from->si_code, &to->si_code);
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if (from->si_code < 0) {
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put_user_ex(from->si_pid, &to->si_pid);
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put_user_ex(from->si_uid, &to->si_uid);
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put_user_ex(ptr_to_compat(from->si_ptr), &to->si_ptr);
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} else {
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/*
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* First 32bits of unions are always present:
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* si_pid === si_band === si_tid === si_addr(LS half)
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*/
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put_user_ex(from->_sifields._pad[0],
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&to->_sifields._pad[0]);
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switch (siginfo_layout(from->si_signo, from->si_code)) {
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case SIL_FAULT:
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if (from->si_signo == SIGBUS &&
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(from->si_code == BUS_MCEERR_AR ||
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from->si_code == BUS_MCEERR_AO))
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put_user_ex(from->si_addr_lsb, &to->si_addr_lsb);
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if (from->si_signo == SIGSEGV) {
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if (from->si_code == SEGV_BNDERR) {
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compat_uptr_t lower = (unsigned long)from->si_lower;
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compat_uptr_t upper = (unsigned long)from->si_upper;
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put_user_ex(lower, &to->si_lower);
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put_user_ex(upper, &to->si_upper);
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}
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if (from->si_code == SEGV_PKUERR)
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put_user_ex(from->si_pkey, &to->si_pkey);
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}
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break;
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case SIL_SYS:
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put_user_ex(from->si_syscall, &to->si_syscall);
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put_user_ex(from->si_arch, &to->si_arch);
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break;
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case SIL_CHLD:
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if (!x32_ABI) {
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put_user_ex(from->si_utime, &to->si_utime);
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put_user_ex(from->si_stime, &to->si_stime);
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} else {
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put_user_ex(from->si_utime, &to->_sifields._sigchld_x32._utime);
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put_user_ex(from->si_stime, &to->_sifields._sigchld_x32._stime);
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}
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put_user_ex(from->si_status, &to->si_status);
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/* FALL THROUGH */
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case SIL_KILL:
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put_user_ex(from->si_uid, &to->si_uid);
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break;
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case SIL_POLL:
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put_user_ex(from->si_fd, &to->si_fd);
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break;
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case SIL_TIMER:
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put_user_ex(from->si_overrun, &to->si_overrun);
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put_user_ex(ptr_to_compat(from->si_ptr),
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&to->si_ptr);
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break;
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case SIL_RT:
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put_user_ex(from->si_uid, &to->si_uid);
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put_user_ex(from->si_int, &to->si_int);
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break;
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}
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}
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} put_user_catch(err);
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return err;
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}
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/* from syscall's path, where we know the ABI */
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int copy_siginfo_to_user32(compat_siginfo_t __user *to, const siginfo_t *from)
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{
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return __copy_siginfo_to_user32(to, from, in_x32_syscall());
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}
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int copy_siginfo_from_user32(siginfo_t *to, compat_siginfo_t __user *from)
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{
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int err = 0;
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u32 ptr32;
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if (!access_ok(VERIFY_READ, from, sizeof(compat_siginfo_t)))
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return -EFAULT;
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get_user_try {
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get_user_ex(to->si_signo, &from->si_signo);
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get_user_ex(to->si_errno, &from->si_errno);
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get_user_ex(to->si_code, &from->si_code);
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get_user_ex(to->si_pid, &from->si_pid);
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get_user_ex(to->si_uid, &from->si_uid);
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get_user_ex(ptr32, &from->si_ptr);
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to->si_ptr = compat_ptr(ptr32);
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} get_user_catch(err);
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return err;
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}
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