Pull x86 fixes from Thomas Gleixner: - Expand the space for uncompressing as the LZ4 worst case does not fit into the currently reserved space - Validate boot parameters more strictly to prevent out of bound access in the decompressor/boot code - Fix off by one errors in get_segment_base() * 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/boot: Prevent faulty bootparams.screeninfo from causing harm x86/boot: Provide more slack space during decompression x86/ldt: Fix off by one in get_segment_base()
Calls to mmu_notifier_invalidate_page() were replaced by calls to
mmu_notifier_invalidate_range() and are now bracketed by calls to
mmu_notifier_invalidate_range_start()/end()
Remove now useless invalidate_page callback.
Changed since v1 (Linus Torvalds)
- remove now useless kvm_arch_mmu_notifier_invalidate_page()
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Tested-by: Mike Galbraith <efault@gmx.de>
Tested-by: Adam Borowski <kilobyte@angband.pl>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: kvm@vger.kernel.org
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull UML fix from Richard Weinberger: "This contains a single fix for a regression which was introduced while the merge window" * 'for-linus-4.13-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml: um: Fix check for _xstate for older hosts
If a zero for the number of lines manages to slip through, scroll() may underflow some offset calculations, causing accesses outside the video memory. Make the check in __putstr() more pessimistic to prevent that. Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1503858223-14983-1-git-send-email-jschoenh@amazon.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
The current slack space is not enough for LZ4, which has a worst case overhead of 0.4% for data that cannot be further compressed. With an LZ4 compressed kernel with an embedded initrd, the output is likely to overwrite the input. Increase the slack space to avoid that. Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1503842124-29718-1-git-send-email-jschoenh@amazon.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
ldt->entries[] is allocated in alloc_ldt_struct(). It has
ldt->nr_entries elements and ldt->nr_entries is capped at LDT_ENTRIES.
So if "idx" is == ldt->nr_entries then we're reading beyond the end of
the buffer. It seems duplicative to have two limit checks when one
would work just as well so I removed the check against LDT_ENTRIES.
The gdt_page.gdt[] array has GDT_ENTRIES entries.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-janitors@vger.kernel.org
Fixes: d07bdfd322d3 ("perf/x86: Fix USER/KERNEL tagging of samples properly")
Link: http://lkml.kernel.org/r/20170818102516.gqwm4xdvvuvjw5ho@mwanda
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull x86 fixes from Ingo Molnar: "Two fixes: one for an ldt_struct handling bug and a cherry-picked objtool fix" * 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/mm: Fix use-after-free of ldt_struct objtool: Fix '-mtune=atom' decoding support in objtool 2.0
The following commit:
39a0526fb3f7 ("x86/mm: Factor out LDT init from context init")
renamed init_new_context() to init_new_context_ldt() and added a new
init_new_context() which calls init_new_context_ldt(). However, the
error code of init_new_context_ldt() was ignored. Consequently, if a
memory allocation in alloc_ldt_struct() failed during a fork(), the
->context.ldt of the new task remained the same as that of the old task
(due to the memcpy() in dup_mm()). ldt_struct's are not intended to be
shared, so a use-after-free occurred after one task exited.
Fix the bug by making init_new_context() pass through the error code of
init_new_context_ldt().
This bug was found by syzkaller, which encountered the following splat:
BUG: KASAN: use-after-free in free_ldt_struct.part.2+0x10a/0x150 arch/x86/kernel/ldt.c:116
Read of size 4 at addr ffff88006d2cb7c8 by task kworker/u9:0/3710
CPU: 1 PID: 3710 Comm: kworker/u9:0 Not tainted 4.13.0-rc4-next-20170811 #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:16 [inline]
dump_stack+0x194/0x257 lib/dump_stack.c:52
print_address_description+0x73/0x250 mm/kasan/report.c:252
kasan_report_error mm/kasan/report.c:351 [inline]
kasan_report+0x24e/0x340 mm/kasan/report.c:409
__asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429
free_ldt_struct.part.2+0x10a/0x150 arch/x86/kernel/ldt.c:116
free_ldt_struct arch/x86/kernel/ldt.c:173 [inline]
destroy_context_ldt+0x60/0x80 arch/x86/kernel/ldt.c:171
destroy_context arch/x86/include/asm/mmu_context.h:157 [inline]
__mmdrop+0xe9/0x530 kernel/fork.c:889
mmdrop include/linux/sched/mm.h:42 [inline]
exec_mmap fs/exec.c:1061 [inline]
flush_old_exec+0x173c/0x1ff0 fs/exec.c:1291
load_elf_binary+0x81f/0x4ba0 fs/binfmt_elf.c:855
search_binary_handler+0x142/0x6b0 fs/exec.c:1652
exec_binprm fs/exec.c:1694 [inline]
do_execveat_common.isra.33+0x1746/0x22e0 fs/exec.c:1816
do_execve+0x31/0x40 fs/exec.c:1860
call_usermodehelper_exec_async+0x457/0x8f0 kernel/umh.c:100
ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431
Allocated by task 3700:
save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
save_stack+0x43/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
kmem_cache_alloc_trace+0x136/0x750 mm/slab.c:3627
kmalloc include/linux/slab.h:493 [inline]
alloc_ldt_struct+0x52/0x140 arch/x86/kernel/ldt.c:67
write_ldt+0x7b7/0xab0 arch/x86/kernel/ldt.c:277
sys_modify_ldt+0x1ef/0x240 arch/x86/kernel/ldt.c:307
entry_SYSCALL_64_fastpath+0x1f/0xbe
Freed by task 3700:
save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
save_stack+0x43/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
__cache_free mm/slab.c:3503 [inline]
kfree+0xca/0x250 mm/slab.c:3820
free_ldt_struct.part.2+0xdd/0x150 arch/x86/kernel/ldt.c:121
free_ldt_struct arch/x86/kernel/ldt.c:173 [inline]
destroy_context_ldt+0x60/0x80 arch/x86/kernel/ldt.c:171
destroy_context arch/x86/include/asm/mmu_context.h:157 [inline]
__mmdrop+0xe9/0x530 kernel/fork.c:889
mmdrop include/linux/sched/mm.h:42 [inline]
__mmput kernel/fork.c:916 [inline]
mmput+0x541/0x6e0 kernel/fork.c:927
copy_process.part.36+0x22e1/0x4af0 kernel/fork.c:1931
copy_process kernel/fork.c:1546 [inline]
_do_fork+0x1ef/0xfb0 kernel/fork.c:2025
SYSC_clone kernel/fork.c:2135 [inline]
SyS_clone+0x37/0x50 kernel/fork.c:2129
do_syscall_64+0x26c/0x8c0 arch/x86/entry/common.c:287
return_from_SYSCALL_64+0x0/0x7a
Here is a C reproducer:
#include <asm/ldt.h>
#include <pthread.h>
#include <signal.h>
#include <stdlib.h>
#include <sys/syscall.h>
#include <sys/wait.h>
#include <unistd.h>
static void *fork_thread(void *_arg)
{
fork();
}
int main(void)
{
struct user_desc desc = { .entry_number = 8191 };
syscall(__NR_modify_ldt, 1, &desc, sizeof(desc));
for (;;) {
if (fork() == 0) {
pthread_t t;
srand(getpid());
pthread_create(&t, NULL, fork_thread, NULL);
usleep(rand() % 10000);
syscall(__NR_exit_group, 0);
}
wait(NULL);
}
}
Note: the reproducer takes advantage of the fact that alloc_ldt_struct()
may use vmalloc() to allocate a large ->entries array, and after
commit:
5d17a73a2ebe ("vmalloc: back off when the current task is killed")
it is possible for userspace to fail a task's vmalloc() by
sending a fatal signal, e.g. via exit_group(). It would be more
difficult to reproduce this bug on kernels without that commit.
This bug only affected kernels with CONFIG_MODIFY_LDT_SYSCALL=y.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: <stable@vger.kernel.org> [v4.6+]
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Fixes: 39a0526fb3f7 ("x86/mm: Factor out LDT init from context init")
Link: http://lkml.kernel.org/r/20170824175029.76040-1-ebiggers3@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The host pkru is restored right after vcpu exit (commit 1be0e61), so KVM_GET_XSAVE will return the host PKRU value instead. Fix this by using the guest PKRU explicitly in fill_xsave and load_xsave. This part is based on a patch by Junkang Fu. The host PKRU data may also not match the value in vcpu->arch.guest_fpu.state, because it could have been changed by userspace since the last time it was saved, so skip loading it in kvm_load_guest_fpu. Reported-by: Junkang Fu <junkang.fjk@alibaba-inc.com> Cc: Yang Zhang <zy107165@alibaba-inc.com> Fixes: 1be0e61c1f255faaeab04a390e00c8b9b9042870 Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Move it to struct kvm_arch_vcpu, replacing guest_pkru_valid with a simple comparison against the host value of the register. The write of PKRU in addition can be skipped if the guest has not enabled the feature. Once we do this, we need not test OSPKE in the host anymore, because guest_CR4.PKE=1 implies host_CR4.PKE=1. The static PKU test is kept to elide the code on older CPUs. Suggested-by: Yang Zhang <zy107165@alibaba-inc.com> Fixes: 1be0e61c1f255faaeab04a390e00c8b9b9042870 Cc: stable@vger.kernel.org Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>