From: Christophe Leroy christophe.leroy@c-s.fr
[ Upstream commit 59a12205d3c32aee4c13ca36889fdf7cfed31126 ]
Introduce lkdtm tests for NULL pointer dereference: check access or exec at NULL address, since these errors tend to be reported differently from the general fault error text. For example from x86:
pr_alert("BUG: unable to handle kernel %s at %px\n", address < PAGE_SIZE ? "NULL pointer dereference" : "paging request", (void *)address);
Signed-off-by: Christophe Leroy christophe.leroy@c-s.fr Signed-off-by: Kees Cook keescook@chromium.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/misc/lkdtm.h | 2 ++ drivers/misc/lkdtm_core.c | 2 ++ drivers/misc/lkdtm_perms.c | 18 ++++++++++++++++++ 3 files changed, 22 insertions(+)
diff --git a/drivers/misc/lkdtm.h b/drivers/misc/lkdtm.h index fdf954c2107f..6abc97b245e4 100644 --- a/drivers/misc/lkdtm.h +++ b/drivers/misc/lkdtm.h @@ -40,7 +40,9 @@ void lkdtm_EXEC_KMALLOC(void); void lkdtm_EXEC_VMALLOC(void); void lkdtm_EXEC_RODATA(void); void lkdtm_EXEC_USERSPACE(void); +void lkdtm_EXEC_NULL(void); void lkdtm_ACCESS_USERSPACE(void); +void lkdtm_ACCESS_NULL(void);
/* lkdtm_rodata.c */ void lkdtm_rodata_do_nothing(void); diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c index b2989f2d3126..035e51bea450 100644 --- a/drivers/misc/lkdtm_core.c +++ b/drivers/misc/lkdtm_core.c @@ -214,7 +214,9 @@ struct crashtype crashtypes[] = { CRASHTYPE(EXEC_VMALLOC), CRASHTYPE(EXEC_RODATA), CRASHTYPE(EXEC_USERSPACE), + CRASHTYPE(EXEC_NULL), CRASHTYPE(ACCESS_USERSPACE), + CRASHTYPE(ACCESS_NULL), CRASHTYPE(WRITE_RO), CRASHTYPE(WRITE_RO_AFTER_INIT), CRASHTYPE(WRITE_KERN), diff --git a/drivers/misc/lkdtm_perms.c b/drivers/misc/lkdtm_perms.c index 45f1c0f96612..1a9dcdaa95f0 100644 --- a/drivers/misc/lkdtm_perms.c +++ b/drivers/misc/lkdtm_perms.c @@ -160,6 +160,11 @@ void lkdtm_EXEC_USERSPACE(void) vm_munmap(user_addr, PAGE_SIZE); }
+void lkdtm_EXEC_NULL(void) +{ + execute_location(NULL, CODE_AS_IS); +} + void lkdtm_ACCESS_USERSPACE(void) { unsigned long user_addr, tmp = 0; @@ -191,6 +196,19 @@ void lkdtm_ACCESS_USERSPACE(void) vm_munmap(user_addr, PAGE_SIZE); }
+void lkdtm_ACCESS_NULL(void) +{ + unsigned long tmp; + unsigned long *ptr = (unsigned long *)NULL; + + pr_info("attempting bad read at %px\n", ptr); + tmp = *ptr; + tmp += 0xc0dec0de; + + pr_info("attempting bad write at %px\n", ptr); + *ptr = tmp; +} + void __init lkdtm_perms_init(void) { /* Make sure we can write to __ro_after_init values during __init */