Correct an obscure PV entry leak in the recent change to amd64's pmap_enter()
ClosedPublic
Actions

Authored by alc on Jul 4 2018, 7:07 PM.

Details

Reviewers

kib
markj

Commits

rS335971: As of r335784, if pmap_enter() replaces a managed mapping by an unmanaged

Summary

Hypothetically, pmap_enter() could replace a managed mapping by an unmanaged mapping, in which case, pmap_enter() would currently leak the unlinked PV entry. This change frees that PV entry when the new mapping is unmanaged.

Diff Detail

Repository

rS FreeBSD src repository - subversion

Lint

Lint Not Applicable

Unit

Tests Not Applicable

Event Timeline

alc created this revision.Jul 4 2018, 7:07 PM

I noticed this bug while reading the i386 pmap code. :)

This revision is now accepted and ready to land.Jul 4 2018, 7:30 PM

kib accepted this revision.Jul 4 2018, 8:05 PM

Closed by commit rS335971: As of r335784, if pmap_enter() replaces a managed mapping by an unmanaged (authored by alc). · Explain WhyJul 5 2018, 2:04 AM

This revision was automatically updated to reflect the committed changes.

Herald added a subscriber: imp. · View Herald TranscriptJul 5 2018, 2:04 AM

In D16130#342002, @markj wrote:

I noticed this bug while reading the i386 pmap code. :)

I'm working on the i386 version. As you may have noticed, the i386 pmap has the CoW problem, but not the PV entry allocation problem.

Revision Contents
Changeset List

Path

Size

head/

sys/

amd64/

pmap.c

2 lines

Diff 44884

View Options

head/sys/amd64/amd64/pmap.c

Show First 20 Lines • Show All 3,497 Lines • ▼ Show 20 Lines	list_scan(int s)

if (get80211len(s, IEEE80211_IOC_SCAN_RESULTS, buf, sizeof(buf), &len) < 0)		if (get80211len(s, IEEE80211_IOC_SCAN_RESULTS, buf, sizeof(buf), &len) < 0)
errx(1, "unable to get scan results");		errx(1, "unable to get scan results");
if (len < sizeof(struct ieee80211req_scan_result))		if (len < sizeof(struct ieee80211req_scan_result))
return;		return;

getchaninfo(s);		getchaninfo(s);

ssidmax = verbose ? IEEE80211_NWID_LEN : 14;		ssidmax = verbose ? IEEE80211_NWID_LEN : 32;
printf("%-.s %-17.17s %4s %4s %-7s %3s %4s\n"		printf("%-.s %-17.17s %4s %4s %-7s %3s %4s\n"
, ssidmax, ssidmax, "SSID/MESH ID"		, ssidmax, ssidmax, "SSID/MESH ID"
, "BSSID"		, "BSSID"
, "CHAN"		, "CHAN"
, "RATE"		, "RATE"
, " S:N"		, " S:N"
, "INT"		, "INT"
, "CAPS"		, "CAPS"
▲ Show 20 Lines • Show All 2,261 Lines • Show Last 20 Lines

Correct an obscure PV entry leak in the recent change to amd64's pmap_enter()ClosedPublicActions