From: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date: Tue, 1 Dec 2020 10:12:32 +0000 (+0000)
Subject: aarch64: align address for BTI protection [BZ #26988]
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c6090dcebd1fc2a39a95b6fd420e072a2039a81b;p=thirdparty%2Fglibc.git

aarch64: align address for BTI protection [BZ #26988]

Handle unaligned executable load segments (the bfd linker is not
expected to produce such binaries, but other linkers may).

Computing the mapping bounds follows _dl_map_object_from_fd more
closely now.

Fixes bug 26988.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
(cherry picked from commit 8b8f616e6a594b91d0afb152384bf2a9f72b7288)
---

diff --git a/sysdeps/aarch64/dl-bti.c b/sysdeps/aarch64/dl-bti.c
index 56c097210ad..779d0fe4887 100644
--- a/sysdeps/aarch64/dl-bti.c
+++ b/sysdeps/aarch64/dl-bti.c
@@ -20,19 +20,22 @@
 #include <libintl.h>
 #include <ldsodefs.h>
 
-static int
+static void
 enable_bti (struct link_map *map, const char *program)
 {
+  const size_t pagesz = GLRO(dl_pagesize);
   const ElfW(Phdr) *phdr;
-  unsigned prot;
 
   for (phdr = map->l_phdr; phdr < &map->l_phdr[map->l_phnum]; ++phdr)
     if (phdr->p_type == PT_LOAD && (phdr->p_flags & PF_X))
       {
-	void *start = (void *) (phdr->p_vaddr + map->l_addr);
-	size_t len = phdr->p_memsz;
+	size_t vstart = ALIGN_DOWN (phdr->p_vaddr, pagesz);
+	size_t vend = ALIGN_UP (phdr->p_vaddr + phdr->p_filesz, pagesz);
+	off_t off = ALIGN_DOWN (phdr->p_offset, pagesz);
+	void *start = (void *) (vstart + map->l_addr);
+	size_t len = vend - vstart;
 
-	prot = PROT_EXEC | PROT_BTI;
+	unsigned prot = PROT_EXEC | PROT_BTI;
 	if (phdr->p_flags & PF_R)
 	  prot |= PROT_READ;
 	if (phdr->p_flags & PF_W)
@@ -48,7 +51,6 @@ enable_bti (struct link_map *map, const char *program)
 				N_("mprotect failed to turn on BTI"));
 	  }
       }
-  return 0;
 }
 
 /* Enable BTI for L and its dependencies.  */