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msdosfs_read(): avoid integer overflow for files > 2GB, when 

difference between current read position and file size
	is bigger than 2GB

This fixes problem first noted in FreeBSD PR#15639 and sent
by Martin J. Laubach in kern/9046, though the implementation
differs a bit.
This commit is contained in:
jdolecek 2000-04-22 22:45:37 +00:00
parent 8ec60a189f
commit 40d9f8a709
1 changed files with 6 additions and 5 deletions
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11
sys/msdosfs/msdosfs_vnops.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: msdosfs_vnops.c,v 1.95 2000/03/30 12:23:20 augustss Exp $ */
/* $NetBSD: msdosfs_vnops.c,v 1.96 2000/04/22 22:45:37 jdolecek Exp $ */
/*-
* Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
@ -466,7 +466,7 @@ msdosfs_read(v)
struct ucred *a_cred;
} */ *ap = v;
int error = 0;
int diff;
int64_t diff;
int blsize;
int isadir;
long n;
@ -492,11 +492,12 @@ msdosfs_read(v)
lbn = de_cluster(pmp, uio->uio_offset);
on = uio->uio_offset & pmp->pm_crbomask;
n = min((u_long) (pmp->pm_bpcluster - on), uio->uio_resid);
diff = dep->de_FileSize - uio->uio_offset;
if (diff <= 0)
if (uio->uio_offset >= dep->de_FileSize)
return (0);
/* file size (and hence diff) may be up to 4GB */
diff = dep->de_FileSize - uio->uio_offset;
if (diff < n)
n = diff;
n = (long) diff;
/* convert cluster # to block # if a directory */
if (isadir) {
error = pcbmap(dep, lbn, &lbn, 0, &blsize);