[glibc] aarch64: align address for BTI protection [BZ #26988]
Szabolcs Nagy
nsz@sourceware.org
Fri Dec 11 15:19:15 GMT 2020
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=8b8f616e6a594b91d0afb152384bf2a9f72b7288
commit 8b8f616e6a594b91d0afb152384bf2a9f72b7288
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date: Tue Dec 1 10:12:32 2020 +0000
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>
Diff:
---
sysdeps/aarch64/dl-bti.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/sysdeps/aarch64/dl-bti.c b/sysdeps/aarch64/dl-bti.c
index 56c097210a..779d0fe488 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. */
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