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

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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)
This commit is contained in:
Szabolcs Nagy 2020-12-01 10:12:32 +00:00
parent 610e2c5150
commit c6090dcebd
1 changed files with 8 additions and 6 deletions
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14
sysdeps/aarch64/dl-bti.c
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@ -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. */