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ksymsmmap: Add missing uao_reference(9) call for ks->ks_uobj. 

Fix failure for savecore(8) and subsequent kernel panic, introduced to
kern_ksyms.c rev 1.03, at least for sh3 and alpha.

For sh3 and alpha, savecore(8) supports coff and ecoff, respectively, via
libkvm via nlist(3). nlist(3) routines for coff and ecoff use mmap(2) and
munmap(2) for /dev/ksyms.

This munmap(2) decrements reference count for ks->ks_uobj. Unless it is
incremented in ksymsmmap(), ks->ks_uobj will be freed unexpectedly.
This commit is contained in:
rin 2021-09-22 05:42:19 +00:00
parent ad3f6413ed
commit d48f610611
1 changed files with 3 additions and 2 deletions
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5
sys/kern/kern_ksyms.c
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@ -1,4 +1,4 @@
/* $NetBSD: kern_ksyms.c,v 1.104 2021/09/11 10:09:55 riastradh Exp $ */
/* $NetBSD: kern_ksyms.c,v 1.105 2021/09/22 05:42:19 rin Exp $ */
/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
@ -73,7 +73,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_ksyms.c,v 1.104 2021/09/11 10:09:55 riastradh Exp $");
__KERNEL_RCSID(0, "$NetBSD: kern_ksyms.c,v 1.105 2021/09/22 05:42:19 rin Exp $");
#if defined(_KERNEL) && defined(_KERNEL_OPT)
#include "opt_copy_symtab.h"
@ -1406,6 +1406,7 @@ ksymsmmap(struct file *fp, off_t *offp, size_t nbytes, int prot, int *flagsp,
return EINVAL; /* XXX ??? */
/* Success! */
uao_reference(ks->ks_uobj);
*advicep = UVM_ADV_SEQUENTIAL;
*uobjp = ks->ks_uobj;
*maxprotp = prot & VM_PROT_READ;