fallocate: fix missing sentinel for is_nul()

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/sys-utils/fallocate.c b/sys-utils/fallocate.c
index e6dac1993e7e46a3b37b3138286dd35db86917dd..d8a74bf9181f2046e558bd10b385d488d3f8fb6a 100644 (file)
--- a/sys-utils/fallocate.c
+++ b/sys-utils/fallocate.c
@@ -130,13 +130,17 @@ static int skip_hole(int fd, off_t *off)
        return -1;              /* no hole */
 }
 
-static int is_nul(void const *buf, size_t bufsize)
+/* The real buffer size has to be bufsize + sizeof(uintptr_t) */
+static int is_nul(void *buf, size_t bufsize)
 {
        typedef uintptr_t word;
        void const *vp;
        char const *cbuf = buf, *cp;
        word const *wp = buf;
 
+       /* set sentinel */
+       memset((char *) buf + bufsize, '\1', sizeof(word));
+
        /* Find first nonzero *word*, or the word with the sentinel.  */
        while (*wp++ == 0)
                continue;
@@ -179,7 +183,8 @@ static void dig_holes(int fd, off_t off, off_t len)
        if (lseek(fd, off, SEEK_SET) < 0)
                err(EXIT_FAILURE, _("seek on %s failed"), filename);
 
-       buf = xmalloc(bufsz);
+       /* buffer + extra space for is_nul() sentinel */
+       buf = xmalloc(bufsz + sizeof(uintptr_t));
        cache_start = off;
 
 #if defined(POSIX_FADV_SEQUENTIAL) && defined(HAVE_POSIX_FADVISE)