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ksyms(4): Reject negative offsets earlier in lseek. 

Avoid arithmetic overflow.

XXX pullup-10
This commit is contained in:
riastradh 2023-02-21 11:40:00 +00:00
parent be8f7ff572
commit e81d26fc71
1 changed files with 8 additions and 5 deletions
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13
sys/kern/kern_ksyms.c
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@ -1,4 +1,4 @@
/* $NetBSD: kern_ksyms.c,v 1.107 2022/07/15 06:40:24 mrg Exp $ */
/* $NetBSD: kern_ksyms.c,v 1.108 2023/02/21 11:40:00 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 1.107 2022/07/15 06:40:24 mrg Exp $");
__KERNEL_RCSID(0, "$NetBSD: kern_ksyms.c,v 1.108 2023/02/21 11:40:00 riastradh Exp $");
#if defined(_KERNEL) && defined(_KERNEL_OPT)
#include "opt_copy_symtab.h"
@ -1417,6 +1417,7 @@ ksymsmmap(struct file *fp, off_t *offp, size_t nbytes, int prot, int *flagsp,
static int
ksymsseek(struct file *fp, off_t delta, int whence, off_t *newoffp, int flags)
{
const off_t OFF_MAX = __type_max(off_t);
struct ksyms_snapshot *ks = fp->f_data;
off_t base, newoff;
int error;
@ -1438,13 +1439,15 @@ ksymsseek(struct file *fp, off_t delta, int whence, off_t *newoffp, int flags)
goto out;
}
/* Compute the new offset and validate it. */
newoff = base + delta; /* XXX arithmetic overflow */
if (newoff < 0) {
/* Check for arithmetic overflow and reject negative offsets. */
if (base < 0 || delta > OFF_MAX - base || base + delta < 0) {
error = EINVAL;
goto out;
}
/* Compute the new offset. */
newoff = base + delta;
/* Success! */
if (newoffp)
*newoffp = newoff;