Module Name: src
Committed By: riastradh
Date: Thu Jun 3 01:00:15 UTC 2021
Modified Files:
src/sys/kern: kern_ksyms.c
Log Message:
ksyms(4): Fix race in ksymsread iteration.
TAILQ_NEXT(ksyms_last_snapshot) might change while we are iterating,
but ksyms_last_snapshot itself cannot, so invert the loop structure.
Discussed with rin@.
To generate a diff of this commit:
cvs rdiff -u -r1.94 -r1.95 src/sys/kern/kern_ksyms.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/kern_ksyms.c
diff -u src/sys/kern/kern_ksyms.c:1.94 src/sys/kern/kern_ksyms.c:1.95
--- src/sys/kern/kern_ksyms.c:1.94 Wed Jun 2 15:43:33 2021
+++ src/sys/kern/kern_ksyms.c Thu Jun 3 01:00:15 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_ksyms.c,v 1.94 2021/06/02 15:43:33 rin Exp $ */
+/* $NetBSD: kern_ksyms.c,v 1.95 2021/06/03 01:00:15 riastradh Exp $ */
/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -73,7 +73,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_ksyms.c,v 1.94 2021/06/02 15:43:33 rin Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_ksyms.c,v 1.95 2021/06/03 01:00:15 riastradh Exp $");
#if defined(_KERNEL) && defined(_KERNEL_OPT)
#include "opt_copy_symtab.h"
@@ -1087,7 +1087,7 @@ ksymsread(dev_t dev, struct uio *uio, in
*/
filepos = sizeof(struct ksyms_hdr);
for (st = TAILQ_FIRST(&ksyms_symtabs);
- st != TAILQ_NEXT(ksyms_last_snapshot, sd_queue);
+ ;
st = TAILQ_NEXT(st, sd_queue)) {
if (__predict_false(st->sd_gone))
continue;
@@ -1101,6 +1101,8 @@ ksymsread(dev_t dev, struct uio *uio, in
return error;
}
filepos += st->sd_symsize;
+ if (st == ksyms_last_snapshot)
+ break;
}
/*
@@ -1109,7 +1111,7 @@ ksymsread(dev_t dev, struct uio *uio, in
KASSERT(filepos <= sizeof(struct ksyms_hdr) +
ksyms_hdr.kh_shdr[SYMTAB].sh_size);
for (st = TAILQ_FIRST(&ksyms_symtabs);
- st != TAILQ_NEXT(ksyms_last_snapshot, sd_queue);
+ ;
st = TAILQ_NEXT(st, sd_queue)) {
if (__predict_false(st->sd_gone))
continue;
@@ -1123,6 +1125,8 @@ ksymsread(dev_t dev, struct uio *uio, in
return error;
}
filepos += st->sd_strsize;
+ if (st == ksyms_last_snapshot)
+ break;
}
/*
