Subject: Re: kern/32631: Bad concurrency checking can cause a crash in sys/kern/subr_pool.c
To: None <firstname.lastname@example.org, email@example.com,>
From: Christos Zoulas <firstname.lastname@example.org>
Date: 01/25/2006 11:22:24
On Jan 25, 4:05pm, email@example.com (firstname.lastname@example.org) wrote:
-- Subject: kern/32631: Bad concurrency checking can cause a crash in sys/ker
| >Number: 32631
| >Category: kern
| >Synopsis: Bad concurrency checking can cause a crash in sys/kern/subr_pool.c
| >Confidential: no
| >Severity: critical
| >Priority: medium
| >Responsible: kern-bug-people
| >State: open
| >Class: sw-bug
| >Submitter-Id: net
| >Arrival-Date: Wed Jan 25 16:05:01 +0000 2006
| >Originator: Yves-Emmanuel JUTARD
| >Release: 3.0.0
| THALES Communication
| custom environment : recompiled from /src, only some parts of NetBSD are used (TCP/IP stack and some parts of the kernel)
| in file sys/kern/subr_pool.c,v 184.108.40.206,
| in function 'pool_get' (l. 796)
| line 1038, pool_get can call "pool_catchup' on a 'entered' pool (pp, locked by 'pr_enter' at line 818)
| now, under specific conditions, pool_catchup(pp) can call pool_allocator_alloc(pp), which can call 'pool_reclaim(pp)' which call 'pr_enter(pp)', which fail and crash, since 'pp' is already entered !
| I have experienced crashes because of that, on our custom board with limited memory.
| Use NetBSD on a low mem system.
| The solution is to call 'pr_leave(pp)' just before calling 'pool_catchup(pp)' in pool_get.
| pr_leave(pp) is normally called AFTER the call to pool_catchup, line 1046.
| I suggest moving it BEFORE, line 1034.
| This is valid because we have finished manipulating the pool, so we can "leave" it peacefully.
| It works for me.
Can you send a diff please?