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Don't bother calling vslock() and vsunlock() if oldlen is zero.

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If vslock() returns ENOMEM, sysctl_wire_old_buffer() should set
wiredlen to zero and return zero (success) so that the handler will
operate according to sysctl(3):
     The size of the buffer is given by the location specified by
     oldlenp before the call, and that location gives the amount
     of data copied after a successful call and after a call that
     returns with the error code ENOMEM.
The handler will return an ENOMEM error because the zero length
buffer will overflow.
This commit is contained in:
truckman 2004-03-16 01:28:45 +00:00
parent 12adb9e4a7
commit 2b0bda9870
1 changed files with 9 additions and 7 deletions
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16
sys/kern/kern_sysctl.c
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@ -999,7 +999,7 @@ kernel_sysctl(struct thread *td, int *name, u_int namelen, void *old,
error = sysctl_root(0, name, namelen, &req);
if (req.lock == REQ_WIRED)
if (req.lock == REQ_WIRED && req.wiredlen > 0)
vsunlock(req.oldptr, req.wiredlen);
SYSCTL_UNLOCK();
@ -1102,13 +1102,15 @@ sysctl_wire_old_buffer(struct sysctl_req *req, size_t len)
ret = 0;
if (req->lock == REQ_LOCKED && req->oldptr &&
req->oldfunc == sysctl_old_user) {
ret = vslock(req->oldptr, wiredlen);
if (ret == 0) {
req->lock = REQ_WIRED;
req->wiredlen = wiredlen;
if (wiredlen != 0) {
ret = vslock(req->oldptr, wiredlen);
if (ret != 0 && ret != ENOMEM)
return (ret);
}
req->lock = REQ_WIRED;
req->wiredlen = wiredlen;
}
return (ret);
return (0);
}
int
@ -1317,7 +1319,7 @@ userland_sysctl(struct thread *td, int *name, u_int namelen, void *old,
} while (error == EAGAIN);
req = req2;
if (req.lock == REQ_WIRED)
if (req.lock == REQ_WIRED && req.wiredlen > 0)
vsunlock(req.oldptr, req.wiredlen);
SYSCTL_UNLOCK();