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Subject[REVIEW][PATCH 1/5] signal/signalfd: Remove __put_user from signalfd_copyinfo
Put a signalfd_siginfo structure on the stack fully initializae
it and then copy it to userspace.

The code is a little less wordy, and this avoids a long series
of the somewhat costly __put_user calls.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
fs/signalfd.c | 56 +++++++++++++++++++++++++++++---------------------------
1 file changed, 29 insertions(+), 27 deletions(-)

diff --git a/fs/signalfd.c b/fs/signalfd.c
index ff302bf50be4..31e960209a08 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -81,41 +81,41 @@ static __poll_t signalfd_poll(struct file *file, poll_table *wait)
static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
siginfo_t const *kinfo)
{
- long err;
+ struct signalfd_siginfo new;

BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);

/*
* Unused members should be zero ...
*/
- err = __clear_user(uinfo, sizeof(*uinfo));
+ memset(&new, 0, sizeof(new));

/*
* If you change siginfo_t structure, please be sure
* this code is fixed accordingly.
*/
- err |= __put_user(kinfo->si_signo, &uinfo->ssi_signo);
- err |= __put_user(kinfo->si_errno, &uinfo->ssi_errno);
- err |= __put_user(kinfo->si_code, &uinfo->ssi_code);
+ new.ssi_signo = kinfo->si_signo;
+ new.ssi_errno = kinfo->si_errno;
+ new.ssi_code = kinfo->si_code;
switch (siginfo_layout(kinfo->si_signo, kinfo->si_code)) {
case SIL_KILL:
- err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
- err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
+ new.ssi_pid = kinfo->si_pid;
+ new.ssi_uid = kinfo->si_uid;
break;
case SIL_TIMER:
- err |= __put_user(kinfo->si_tid, &uinfo->ssi_tid);
- err |= __put_user(kinfo->si_overrun, &uinfo->ssi_overrun);
- err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
- err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
+ new.ssi_tid = kinfo->si_tid;
+ new.ssi_overrun = kinfo->si_overrun;
+ new.ssi_ptr = (long) kinfo->si_ptr;
+ new.ssi_int = kinfo->si_int;
break;
case SIL_POLL:
- err |= __put_user(kinfo->si_band, &uinfo->ssi_band);
- err |= __put_user(kinfo->si_fd, &uinfo->ssi_fd);
+ new.ssi_band = kinfo->si_band;
+ new.ssi_fd = kinfo->si_fd;
break;
case SIL_FAULT:
- err |= __put_user((long) kinfo->si_addr, &uinfo->ssi_addr);
+ new.ssi_addr = (long) kinfo->si_addr;
#ifdef __ARCH_SI_TRAPNO
- err |= __put_user(kinfo->si_trapno, &uinfo->ssi_trapno);
+ new.ssi_trapno = kinfo->si_trapno;
#endif
/*
* Other callers might not initialize the si_lsb field,
@@ -124,29 +124,31 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
if (kinfo->si_signo == SIGBUS &&
((kinfo->si_code == BUS_MCEERR_AR) ||
(kinfo->si_code == BUS_MCEERR_AO)))
- err |= __put_user((short) kinfo->si_addr_lsb,
- &uinfo->ssi_addr_lsb);
+ new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
break;
case SIL_CHLD:
- err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
- err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
- err |= __put_user(kinfo->si_status, &uinfo->ssi_status);
- err |= __put_user(kinfo->si_utime, &uinfo->ssi_utime);
- err |= __put_user(kinfo->si_stime, &uinfo->ssi_stime);
+ new.ssi_pid = kinfo->si_pid;
+ new.ssi_uid = kinfo->si_uid;
+ new.ssi_status = kinfo->si_status;
+ new.ssi_utime = kinfo->si_utime;
+ new.ssi_stime = kinfo->si_stime;
break;
case SIL_RT:
default:
/*
* This case catches also the signals queued by sigqueue().
*/
- err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
- err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
- err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
- err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
+ new.ssi_pid = kinfo->si_pid;
+ new.ssi_uid = kinfo->si_uid;
+ new.ssi_ptr = (long) kinfo->si_ptr;
+ new.ssi_int = kinfo->si_int;
break;
}

- return err ? -EFAULT: sizeof(*uinfo);
+ if (copy_to_user(uinfo, &new, sizeof(struct signalfd_siginfo)))
+ return -EFAULT;
+
+ return sizeof(*uinfo);
}

static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info,
--
2.14.1
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