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link_elf_obj: Invoke fini callbacks

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This is required for KASAN: when a module is unloaded, poisoned regions
(e.g., pad areas between global variables) are left as such, so if they
are reused as KLDs are loaded, false positives can arise.

Reported by:	pho, Jenkins
Reviewed by:	kib
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D31339
This commit is contained in:
Mark Johnston 2021-07-29 09:46:25 -04:00
parent 98bfb9dac2
commit 9e575fadf4
3 changed files with 35 additions and 5 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
sys/kern/kern_linker.c
View file

@ -613,6 +613,8 @@ linker_make_file(const char *pathname, linker_class_t lc)
return (NULL);
lf->ctors_addr = 0;
lf->ctors_size = 0;
lf->dtors_addr = 0;
lf->dtors_size = 0;
lf->refs = 1;
lf->userrefs = 0;
lf->flags = 0;

32
sys/kern/link_elf_obj.c
View file

@ -544,6 +544,17 @@ link_elf_link_preload(linker_class_t cls, const char *filename,
lf->ctors_addr = ef->progtab[pb].addr;
lf->ctors_size = shdr[i].sh_size;
}
} else if ((ef->progtab[pb].name != NULL &&
strcmp(ef->progtab[pb].name, ".dtors") == 0) ||
shdr[i].sh_type == SHT_FINI_ARRAY) {
if (lf->dtors_addr != 0) {
printf(
"%s: multiple dtor sections in %s\n",
__func__, filename);
} else {
lf->dtors_addr = ef->progtab[pb].addr;
lf->dtors_size = shdr[i].sh_size;
}
}
/* Update all symbol values with the offset. */
@ -612,7 +623,7 @@ out:
}
static void
link_elf_invoke_ctors(caddr_t addr, size_t size)
link_elf_invoke_cbs(caddr_t addr, size_t size)
{
void (**ctor)(void);
size_t i, cnt;
@ -653,7 +664,7 @@ link_elf_link_preload_finish(linker_file_t lf)
/* Apply protections now that relocation processing is complete. */
link_elf_protect(ef);
link_elf_invoke_ctors(lf->ctors_addr, lf->ctors_size);
link_elf_invoke_cbs(lf->ctors_addr, lf->ctors_size);
return (0);
}
@ -1012,6 +1023,19 @@ link_elf_load_file(linker_class_t cls, const char *filename,
lf->ctors_size =
shdr[i].sh_size;
}
} else if (!strcmp(ef->progtab[pb].name,
".dtors") ||
shdr[i].sh_type == SHT_FINI_ARRAY) {
if (lf->dtors_addr != 0) {
printf(
"%s: multiple dtor sections in %s\n",
__func__, filename);
} else {
lf->dtors_addr =
(caddr_t)mapbase;
lf->dtors_size =
shdr[i].sh_size;
}
}
} else if (shdr[i].sh_type == SHT_PROGBITS)
ef->progtab[pb].name = "<<PROGBITS>>";
@ -1196,7 +1220,7 @@ link_elf_load_file(linker_class_t cls, const char *filename,
#endif
link_elf_protect(ef);
link_elf_invoke_ctors(lf->ctors_addr, lf->ctors_size);
link_elf_invoke_cbs(lf->ctors_addr, lf->ctors_size);
*result = lf;
out:
@ -1216,6 +1240,8 @@ link_elf_unload_file(linker_file_t file)
elf_file_t ef = (elf_file_t) file;
u_int i;
link_elf_invoke_cbs(file->dtors_addr, file->dtors_size);
/* Notify MD code that a module is being unloaded. */
elf_cpu_unload_file(file);

6
sys/sys/linker.h
View file

@ -82,8 +82,10 @@ struct linker_file {
int id; /* unique id */
caddr_t address; /* load address */
size_t size; /* size of file */
caddr_t ctors_addr; /* address of .ctors */
size_t ctors_size; /* size of .ctors */
caddr_t ctors_addr; /* address of .ctors/.init_array */
size_t ctors_size; /* size of .ctors/.init_array */
caddr_t dtors_addr; /* address of .dtors/.fini_array */
size_t dtors_size; /* size of .dtors/.fini_array */
int ndeps; /* number of dependencies */
linker_file_t* deps; /* list of dependencies */
STAILQ_HEAD(, common_symbol) common; /* list of common symbols */