reads: fix bug 1078

1 files changed, 2 insertions, 1 deletions

diff --git a/libbb/read.c b/libbb/read.c
index 1c2945f45..b3648b4d7 100644
--- a/libbb/read.c
+++ b/libbb/read.c
@@ -86,7 +86,8 @@ char *reads(int fd, char *buffer, size_t size)
         if (p) {
                 off_t offset;
                 *p++ = '\0';
-                offset = (p-buffer) - size;
+                // avoid incorrect (unsigned) widening
+                offset = (off_t)(p-buffer) - (off_t)size;
                 // set fd position the right after the \n
                 if (offset && lseek(fd, offset, SEEK_CUR) == (off_t)-1)
                         return NULL;