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Commit ba9f901c authored by Kees Cook's avatar Kees Cook Committed by Satya Tangirala
Browse files

BACKPORT: lkdtm: add bad USER_DS test 



(cherry-picked from e22aa9d781a27a961581c57442911309fb86a48e)

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.

Change-Id: I8fab22ce9cf9ef44028ce712f58bcfe4b2821929
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarSatya Tangirala <satyat@google.com>
parent eb235bf1

drivers/misc/lkdtm.h

+1 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ void lkdtm_ATOMIC_UNDERFLOW(void); 
void lkdtm_ATOMIC_OVERFLOW(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

+10 −0
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 
#include "lkdtm.h"

#include <linux/list.h>

#include <linux/sched.h>

#include <linux/uaccess.h>



struct lkdtm_list {

	struct list_head node;
@@ -214,3 +215,12 @@ 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),