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Commit e22aa9d7 authored by Kees Cook's avatar Kees Cook Committed by Greg Kroah-Hartman
Browse files

lkdtm: add bad USER_DS test 



This adds CORRUPT_USER_DS to check that the get_fs() test on syscall
return (via __VERIFY_PRE_USERMODE_STATE) still sees USER_DS. Since
trying to deal with values other than USER_DS and KERNEL_DS across all
architectures in a safe way is not sensible, this sets KERNEL_DS, but
since that could be extremely dangerous if the protection is not present,
it also raises SIGKILL for current, so that no matter what, the process
will die. A successful test will be visible with a BUG(), like all the
other LKDTM tests.

Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 8ab44b40

drivers/misc/lkdtm.h

+1 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ void lkdtm_REFCOUNT_ZERO_SUB(void); 
void lkdtm_REFCOUNT_ZERO_ADD(void);

void lkdtm_CORRUPT_LIST_ADD(void);

void lkdtm_CORRUPT_LIST_DEL(void);

void lkdtm_CORRUPT_USER_DS(void);



/* lkdtm_heap.c */

void lkdtm_OVERWRITE_ALLOCATION(void);

drivers/misc/lkdtm_bugs.c

+11 −0
Original line number Diff line number Diff line
@@ -8,6 +8,8 @@ 
#include <linux/list.h>

#include <linux/refcount.h>

#include <linux/sched.h>

#include <linux/sched/signal.h>

#include <linux/uaccess.h>



struct lkdtm_list {

	struct list_head node;
@@ -279,3 +281,12 @@ void lkdtm_CORRUPT_LIST_DEL(void) 
	else

		pr_err("list_del() corruption not detected!\n");

}



void lkdtm_CORRUPT_USER_DS(void)

{

	pr_info("setting bad task size limit\n");

	set_fs(KERNEL_DS);



	/* Make sure we do not keep running with a KERNEL_DS! */

	force_sig(SIGKILL, current);

}

drivers/misc/lkdtm_core.c

+1 −0
Original line number Diff line number Diff line
@@ -199,6 +199,7 @@ struct crashtype crashtypes[] = { 
	CRASHTYPE(OVERFLOW),

	CRASHTYPE(CORRUPT_LIST_ADD),

	CRASHTYPE(CORRUPT_LIST_DEL),

	CRASHTYPE(CORRUPT_USER_DS),

	CRASHTYPE(CORRUPT_STACK),

	CRASHTYPE(UNALIGNED_LOAD_STORE_WRITE),

	CRASHTYPE(OVERWRITE_ALLOCATION),