libdl: fix size parameter when unmap library in dlclose

Fix size parameter when unmap a library by means of dlclose, by
taking into account the p_vaddr of first PT_LOAD segment, so it works
also for prelinked shared objects.
Unmapping of dlopen shared libraries is broken since
94cc6edb78a12655c0602a246fa1cbdc8c6d0ad9

Signed-off-by: Filippo Arcidiacono <filippo.arcidiacono@st.com>
Signed-off-by: Carmelo Amoroso <carmelo.amoroso@st.com>

ldso/libdl/libdl.c

@@ -751,7 +751,7 @@ static int do_dlclose(void *vhandle, int need_fini)
 	int (*dl_elf_fini) (void);
 	void (*dl_brk) (void);
 	struct dyn_elf *handle;
-	unsigned int end;
+	unsigned int end = 0, start = 0xffffffff;
 	unsigned int i, j;
 	struct r_scope_elem *ls;
 #if defined(USE_TLS) && USE_TLS
@@ -813,6 +813,8 @@ static int do_dlclose(void *vhandle, int need_fini)
 					i < tpnt->n_phent; ppnt++, i++) {
 				if (ppnt->p_type != PT_LOAD)
 					continue;
+				if (ppnt->p_vaddr < start)
+					start = ppnt->p_vaddr;
 				if (end < ppnt->p_vaddr + ppnt->p_memsz)
 					end = ppnt->p_vaddr + ppnt->p_memsz;
 			}
@@ -919,7 +921,9 @@ static int do_dlclose(void *vhandle, int need_fini)
 			}
 #endif
 
-			DL_LIB_UNMAP (tpnt, end - tpnt->mapaddr);
+			end = (end + ADDR_ALIGN) & PAGE_ALIGN;
+			start = start & ~ADDR_ALIGN;
+			DL_LIB_UNMAP (tpnt, end - start);
 			/* Free elements in RTLD_LOCAL scope list */
 			for (runp = tpnt->rtld_local; runp; runp = tmp) {
 				tmp = runp->next;