From e64a1618af8566d20991607913a4d90d39b30118 Mon Sep 17 00:00:00 2001 From: Sven Schnelle Date: Wed, 17 Jun 2020 17:30:28 +0200 Subject: s390: fix system call single stepping When single stepping an svc instruction on s390, the kernel is entered with a PER program check interruption. The program check handler than jumps to the system call handler by reloading the PSW. The code didn't set GPR13 to the thread pointer in struct task_struct. This made the kernel access invalid memory while trying to fetch the syscall function address. Fix this by always assigned GPR13 after .Lsysc_per. Fixes: 0b0ed657fe00 ("s390: remove critical section cleanup from entry.S") Reported-and-tested-by: Christian Borntraeger Signed-off-by: Sven Schnelle Reviewed-by: Heiko Carstens Signed-off-by: Heiko Carstens --- arch/s390/kernel/entry.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index 496f74d98473..969b35b177dd 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -378,9 +378,9 @@ ENTRY(system_call) stmg %r8,%r15,__LC_SAVE_AREA_SYNC BPOFF lg %r12,__LC_CURRENT - lghi %r13,__TASK_thread lghi %r14,_PIF_SYSCALL .Lsysc_per: + lghi %r13,__TASK_thread lg %r15,__LC_KERNEL_STACK la %r11,STACK_FRAME_OVERHEAD(%r15) # pointer to pt_regs UPDATE_VTIME %r8,%r9,__LC_SYNC_ENTER_TIMER -- cgit v1.2.3 From 998f5bbe3dbdab81c1cfb1aef7c3892f5d24f6c7 Mon Sep 17 00:00:00 2001 From: Vasily Gorbik Date: Wed, 17 Jun 2020 15:05:49 +0200 Subject: s390/kasan: fix early pgm check handler execution Currently if early_pgm_check_handler is called it ends up in pgm check loop. The problem is that early_pgm_check_handler is instrumented by KASAN but executed without DAT flag enabled which leads to addressing exception when KASAN checks try to access shadow memory. Fix that by executing early handlers with DAT flag on under KASAN as expected. Reported-and-tested-by: Alexander Egorenkov Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Heiko Carstens --- arch/s390/kernel/early.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c index cd241ee66eff..078277231858 100644 --- a/arch/s390/kernel/early.c +++ b/arch/s390/kernel/early.c @@ -170,6 +170,8 @@ static noinline __init void setup_lowcore_early(void) psw_t psw; psw.mask = PSW_MASK_BASE | PSW_DEFAULT_KEY | PSW_MASK_EA | PSW_MASK_BA; + if (IS_ENABLED(CONFIG_KASAN)) + psw.mask |= PSW_MASK_DAT; psw.addr = (unsigned long) s390_base_ext_handler; S390_lowcore.external_new_psw = psw; psw.addr = (unsigned long) s390_base_pgm_handler; -- cgit v1.2.3 From 827c4913923e0b441ba07ba4cc41e01181102303 Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Tue, 31 Mar 2020 05:57:23 -0400 Subject: s390/debug: avoid kernel warning on too large number of pages When specifying insanely large debug buffers a kernel warning is printed. The debug code does handle the error gracefully, though. Instead of duplicating the check let us silence the warning to avoid crashes when panic_on_warn is used. Signed-off-by: Christian Borntraeger Reviewed-by: Heiko Carstens Signed-off-by: Heiko Carstens --- arch/s390/kernel/debug.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/s390/kernel/debug.c b/arch/s390/kernel/debug.c index 636446003a06..263075a1af36 100644 --- a/arch/s390/kernel/debug.c +++ b/arch/s390/kernel/debug.c @@ -198,9 +198,10 @@ static debug_entry_t ***debug_areas_alloc(int pages_per_area, int nr_areas) if (!areas) goto fail_malloc_areas; for (i = 0; i < nr_areas; i++) { + /* GFP_NOWARN to avoid user triggerable WARN, we handle fails */ areas[i] = kmalloc_array(pages_per_area, sizeof(debug_entry_t *), - GFP_KERNEL); + GFP_KERNEL | __GFP_NOWARN); if (!areas[i]) goto fail_malloc_areas2; for (j = 0; j < pages_per_area; j++) { -- cgit v1.2.3