nlist: Fix pread() return value check

We should check for partial reads, and not continue in those cases,
as we are not retrying them, otherwise we might end up operating on
uninitialized data.
Reported-by: Daniel Hodson <daniel@elttam.com.au>
Based-on-patch-by: Daniel Hodson <daniel@elttam.com.au>
Signed-off-by: Guillem Jover <guillem@hadrons.org>

src/nlist.c

@@ -161,7 +161,7 @@ __fdnlist(int fd, struct nlist *list)
 		return (-1);
 
 	/* Load section header table. */
-	if (pread(fd, shdr, (size_t)shdr_size, (off_t)ehdr.e_shoff) < 0)
+	if (pread(fd, shdr, (size_t)shdr_size, (off_t)ehdr.e_shoff) != (ssize_t)shdr_size)
 		goto done;
 
 	/*
@@ -198,7 +198,7 @@ __fdnlist(int fd, struct nlist *list)
 	if (strtab == NULL)
 		goto done;
 
-	if (pread(fd, strtab, (size_t)symstrsize, (off_t)symstroff) < 0)
+	if (pread(fd, strtab, (size_t)symstrsize, (off_t)symstroff) != (ssize_t)symstrsize)
 		goto done;
 
 	/*