Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commit0f714c6

Browse files
committed
Fix dangling smgr_owner pointer when a fake relcache entry is freed.
A fake relcache entry can "own" a SmgrRelation object, like a regularrelcache entry. But when it was free'd, the owner field in SmgrRelationwas not cleared, so it was left pointing to free'd memory.Amazingly this apparently hasn't caused crashes in practice, or we would'veheard about it earlier. Andres found this with Valgrind.Report and fix by Andres Freund, with minor modifications by me. Backpatchto all supported versions.
1 parentd8f2858 commit0f714c6

File tree

3 files changed

+22
-0
lines changed

3 files changed

+22
-0
lines changed

‎src/backend/access/transam/xlogutils.c

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -414,6 +414,9 @@ CreateFakeRelcacheEntry(RelFileNode rnode)
414414
void
415415
FreeFakeRelcacheEntry(Relationfakerel)
416416
{
417+
/* make sure the fakerel is not referenced by the SmgrRelation anymore */
418+
if (fakerel->rd_smgr!=NULL)
419+
smgrclearowner(&fakerel->rd_smgr,fakerel->rd_smgr);
417420
pfree(fakerel);
418421
}
419422

‎src/backend/storage/smgr/smgr.c

Lines changed: 18 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -197,6 +197,24 @@ smgrsetowner(SMgrRelation *owner, SMgrRelation reln)
197197
*owner=reln;
198198
}
199199

200+
/*
201+
* smgrclearowner() -- Remove long-lived reference to an SMgrRelation object
202+
* if one exists
203+
*/
204+
void
205+
smgrclearowner(SMgrRelation*owner,SMgrRelationreln)
206+
{
207+
/* Do nothing if the SMgrRelation object is not owned by the owner */
208+
if (reln->smgr_owner!=owner)
209+
return;
210+
211+
/* unset the owner's reference */
212+
*owner=NULL;
213+
214+
/* unset our reference to the owner */
215+
reln->smgr_owner=NULL;
216+
}
217+
200218
/*
201219
*smgrexists() -- Does the underlying file for a fork exist?
202220
*/

‎src/include/storage/smgr.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -73,6 +73,7 @@ extern void smgrinit(void);
7373
externSMgrRelationsmgropen(RelFileNodernode);
7474
externboolsmgrexists(SMgrRelationreln,ForkNumberforknum);
7575
externvoidsmgrsetowner(SMgrRelation*owner,SMgrRelationreln);
76+
externvoidsmgrclearowner(SMgrRelation*owner,SMgrRelationreln);
7677
externvoidsmgrclose(SMgrRelationreln);
7778
externvoidsmgrcloseall(void);
7879
externvoidsmgrclosenode(RelFileNodernode);

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp