diff options
| author | Sven Schnelle <svens@linux.ibm.com> | 2020-01-22 13:38:22 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-04-13 10:48:06 +0200 |
| commit | 5e331978200e379c525394aa0863cece328c3dee (patch) | |
| tree | 8ba4f0752f02d9d05e4b35244c7a229a665b9039 /arch/s390/kernel/setup.c | |
| parent | 74107d56d1e8e6ac5a061059941b7e2d03522df6 (diff) | |
s390: prevent leaking kernel address in BEAR
commit 0b38b5e1d0e2f361e418e05c179db05bb688bbd6 upstream.
When userspace executes a syscall or gets interrupted,
BEAR contains a kernel address when returning to userspace.
This make it pretty easy to figure out where the kernel is
mapped even with KASLR enabled. To fix this, add lpswe to
lowcore and always execute it there, so userspace sees only
the lowcore address of lpswe. For this we have to extend
both critical_cleanup and the SWITCH_ASYNC macro to also check
for lpswe addresses in lowcore.
Fixes: b2d24b97b2a9 ("s390/kernel: add support for kernel address space layout randomization (KASLR)")
Cc: <stable@vger.kernel.org> # v5.2+
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/s390/kernel/setup.c')
| -rw-r--r-- | arch/s390/kernel/setup.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c index b95e6fa34cc8..4366962f4930 100644 --- a/arch/s390/kernel/setup.c +++ b/arch/s390/kernel/setup.c @@ -73,6 +73,7 @@ #include <asm/nospec-branch.h> #include <asm/mem_detect.h> #include <asm/uv.h> +#include <asm/asm-offsets.h> #include "entry.h" /* @@ -457,6 +458,8 @@ static void __init setup_lowcore_dat_off(void) lc->spinlock_index = 0; arch_spin_lock_setup(0); lc->br_r1_trampoline = 0x07f1; /* br %r1 */ + lc->return_lpswe = gen_lpswe(__LC_RETURN_PSW); + lc->return_mcck_lpswe = gen_lpswe(__LC_RETURN_MCCK_PSW); set_prefix((u32)(unsigned long) lc); lowcore_ptr[0] = lc; |