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authorRich Felker <dalias@aerifal.cx>2011-09-04 00:06:01 -0400
committerRich Felker <dalias@aerifal.cx>2011-09-04 00:06:01 -0400
commit32d67e938e8da0f37c59247acee8b10eaf9a113c (patch)
treee87b7b5da7700f8af18ce90ceef850398ba9947c /src
parentd4fa6f0e08ff5a292d2aeeeeda80670a1a082cae (diff)
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fix twos complement overflow bug in mem streams boundary check
the expression -off is not safe in case off is the most-negative
value. instead apply - to base which is known to be non-negative and
bounded within sanity.
Diffstat (limited to 'src')
-rw-r--r--src/stdio/open_memstream.c2
-rw-r--r--src/stdio/open_wmemstream.c2
2 files changed, 2 insertions, 2 deletions
diff --git a/src/stdio/open_memstream.c b/src/stdio/open_memstream.c
index 2f3569f1..57737098 100644
--- a/src/stdio/open_memstream.c
+++ b/src/stdio/open_memstream.c
@@ -28,7 +28,7 @@ static off_t ms_seek(FILE *f, off_t off, int whence)
 		errno = EINVAL;
 		return -1;
 	}
-	if (-off > base || off > SSIZE_MAX-base) goto fail;
+	if (off < -base || off > SSIZE_MAX-base) goto fail;
 	return c->pos = base+off;
 }
 
diff --git a/src/stdio/open_wmemstream.c b/src/stdio/open_wmemstream.c
index 3bc0f254..41b92d21 100644
--- a/src/stdio/open_wmemstream.c
+++ b/src/stdio/open_wmemstream.c
@@ -29,7 +29,7 @@ static off_t wms_seek(FILE *f, off_t off, int whence)
 		errno = EINVAL;
 		return -1;
 	}
-	if (-off > base || off > SSIZE_MAX/4-base) goto fail;
+	if (off < -base || off > SSIZE_MAX/4-base) goto fail;
 	memset(&c->mbs, 0, sizeof c->mbs);
 	return c->pos = base+off;
 }