Revert r192094. The revision caused problems for sysctl(3) consumers

that expect that oldlen is filled with required buffer length even when
supplied buffer is too short and returned error is ENOMEM.

Redo the fix for kern.proc.filedesc, by reverting the req->oldidx when
remaining buffer space is too short for the current kinfo_file structure.
Also, only ignore ENOMEM. We have to convert ENOMEM to no error condition
to keep existing interface for the sysctl, though.

Reported by:	ed, Florian Smeets <flo kasimir com>
Tested by:	pho

1 files changed, 3 insertions, 5 deletions

diff --git a/sys/kern/kern_sysctl.c b/sys/kern/kern_sysctl.c
index bf539be..0a8a096 100644
--- a/sys/kern/kern_sysctl.c
+++ b/sys/kern/kern_sysctl.c
@@ -1223,9 +1223,9 @@ sysctl_old_kernel(struct sysctl_req *req, const void *p, size_t l)
 		if (i > 0)
 			bcopy(p, (char *)req->oldptr + req->oldidx, i);
 	}
+	req->oldidx += l;
 	if (req->oldptr && i != l)
 		return (ENOMEM);
-	req->oldidx += l;
 	return (0);
 }
 
@@ -1322,10 +1322,9 @@ sysctl_old_user(struct sysctl_req *req, const void *p, size_t l)
 	size_t i, len, origidx;
 
 	origidx = req->oldidx;
-	if (req->oldptr == NULL) {
-		req->oldidx += l;
+	req->oldidx += l;
+	if (req->oldptr == NULL)
 		return (0);
-	}
 	/*
 	 * If we have not wired the user supplied buffer and we are currently
 	 * holding locks, drop a witness warning, as it's possible that
@@ -1347,7 +1346,6 @@ sysctl_old_user(struct sysctl_req *req, const void *p, size_t l)
 		return (error);
 	if (i < l)
 		return (ENOMEM);
-	req->oldidx += l;
 	return (0);
 }