From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org,
Jan Kratochvil <jan.kratochvil@redhat.com>,
Oleg Nesterov <oleg@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: [PATCH 4.14 39/43] x86: Introduce TS_COMPAT_RESTART to fix get_nr_restart_syscall()
Date: Mon, 22 Mar 2021 13:29:20 +0100 [thread overview]
Message-ID: <20210322121921.284199713@linuxfoundation.org> (raw)
In-Reply-To: <20210322121920.053255560@linuxfoundation.org>
From: Oleg Nesterov <oleg@redhat.com>
commit 8c150ba2fb5995c84a7a43848250d444a3329a7d upstream.
The comment in get_nr_restart_syscall() says:
* The problem is that we can get here when ptrace pokes
* syscall-like values into regs even if we're not in a syscall
* at all.
Yes, but if not in a syscall then the
status & (TS_COMPAT|TS_I386_REGS_POKED)
check below can't really help:
- TS_COMPAT can't be set
- TS_I386_REGS_POKED is only set if regs->orig_ax was changed by
32bit debugger; and even in this case get_nr_restart_syscall()
is only correct if the tracee is 32bit too.
Suppose that a 64bit debugger plays with a 32bit tracee and
* Tracee calls sleep(2) // TS_COMPAT is set
* User interrupts the tracee by CTRL-C after 1 sec and does
"(gdb) call func()"
* gdb saves the regs by PTRACE_GETREGS
* does PTRACE_SETREGS to set %rip='func' and %orig_rax=-1
* PTRACE_CONT // TS_COMPAT is cleared
* func() hits int3.
* Debugger catches SIGTRAP.
* Restore original regs by PTRACE_SETREGS.
* PTRACE_CONT
get_nr_restart_syscall() wrongly returns __NR_restart_syscall==219, the
tracee calls ia32_sys_call_table[219] == sys_madvise.
Add the sticky TS_COMPAT_RESTART flag which survives after return to user
mode. It's going to be removed in the next step again by storing the
information in the restart block. As a further cleanup it might be possible
to remove also TS_I386_REGS_POKED with that.
Test-case:
$ cvs -d :pserver:anoncvs:anoncvs@sourceware.org:/cvs/systemtap co ptrace-tests
$ gcc -o erestartsys-trap-debuggee ptrace-tests/tests/erestartsys-trap-debuggee.c --m32
$ gcc -o erestartsys-trap-debugger ptrace-tests/tests/erestartsys-trap-debugger.c -lutil
$ ./erestartsys-trap-debugger
Unexpected: retval 1, errno 22
erestartsys-trap-debugger: ptrace-tests/tests/erestartsys-trap-debugger.c:421
Fixes: 609c19a385c8 ("x86/ptrace: Stop setting TS_COMPAT in ptrace code")
Reported-by: Jan Kratochvil <jan.kratochvil@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210201174709.GA17895@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/include/asm/thread_info.h | 14 +++++++++++++-
arch/x86/kernel/signal.c | 24 +-----------------------
2 files changed, 14 insertions(+), 24 deletions(-)
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -238,10 +238,22 @@ static inline int arch_within_stack_fram
*/
#define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/
+#ifndef __ASSEMBLY__
#ifdef CONFIG_COMPAT
#define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */
+#define TS_COMPAT_RESTART 0x0008
+
+#define arch_set_restart_data arch_set_restart_data
+
+static inline void arch_set_restart_data(struct restart_block *restart)
+{
+ struct thread_info *ti = current_thread_info();
+ if (ti->status & TS_COMPAT)
+ ti->status |= TS_COMPAT_RESTART;
+ else
+ ti->status &= ~TS_COMPAT_RESTART;
+}
#endif
-#ifndef __ASSEMBLY__
#ifdef CONFIG_X86_32
#define in_ia32_syscall() true
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -769,30 +769,8 @@ handle_signal(struct ksignal *ksig, stru
static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
{
- /*
- * This function is fundamentally broken as currently
- * implemented.
- *
- * The idea is that we want to trigger a call to the
- * restart_block() syscall and that we want in_ia32_syscall(),
- * in_x32_syscall(), etc. to match whatever they were in the
- * syscall being restarted. We assume that the syscall
- * instruction at (regs->ip - 2) matches whatever syscall
- * instruction we used to enter in the first place.
- *
- * The problem is that we can get here when ptrace pokes
- * syscall-like values into regs even if we're not in a syscall
- * at all.
- *
- * For now, we maintain historical behavior and guess based on
- * stored state. We could do better by saving the actual
- * syscall arch in restart_block or (with caveats on x32) by
- * checking if regs->ip points to 'int $0x80'. The current
- * behavior is incorrect if a tracer has a different bitness
- * than the tracee.
- */
#ifdef CONFIG_IA32_EMULATION
- if (current_thread_info()->status & (TS_COMPAT|TS_I386_REGS_POKED))
+ if (current_thread_info()->status & TS_COMPAT_RESTART)
return __NR_ia32_restart_syscall;
#endif
#ifdef CONFIG_X86_X32_ABI
next prev parent reply other threads:[~2021-03-22 12:59 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-22 12:28 [PATCH 4.14 00/43] 4.14.227-rc1 review Greg Kroah-Hartman
2021-03-22 12:28 ` [PATCH 4.14 01/43] ext4: handle error of ext4_setup_system_zone() on remount Greg Kroah-Hartman
2021-03-22 12:28 ` [PATCH 4.14 02/43] ext4: dont allow overlapping system zones Greg Kroah-Hartman
2021-03-22 12:28 ` [PATCH 4.14 03/43] ext4: check journal inode extents more carefully Greg Kroah-Hartman
2021-03-22 12:28 ` [PATCH 4.14 04/43] bpf: Fix off-by-one for area size in creating mask to left Greg Kroah-Hartman
2021-03-22 12:28 ` [PATCH 4.14 05/43] bpf: Simplify alu_limit masking for pointer arithmetic Greg Kroah-Hartman
2021-03-22 12:28 ` [PATCH 4.14 06/43] bpf: Add sanity check for upper ptr_limit Greg Kroah-Hartman
2021-03-22 12:28 ` [PATCH 4.14 07/43] net: dsa: b53: Support setting learning on port Greg Kroah-Hartman
2021-03-22 12:28 ` [PATCH 4.14 08/43] bpf: Prohibit alu ops for pointer types not defining ptr_limit Greg Kroah-Hartman
2021-03-22 12:28 ` [PATCH 4.14 09/43] Revert "PM: runtime: Update device status before letting suppliers suspend" Greg Kroah-Hartman
2021-03-22 12:28 ` [PATCH 4.14 10/43] perf tools: Use %define api.pure full instead of %pure-parser Greg Kroah-Hartman
2021-03-22 12:28 ` [PATCH 4.14 11/43] tools build feature: Check if get_current_dir_name() is available Greg Kroah-Hartman
2021-03-22 12:28 ` [PATCH 4.14 12/43] tools build feature: Check if eventfd() " Greg Kroah-Hartman
2021-03-22 12:28 ` [PATCH 4.14 13/43] tools build: Check if gettid() is available before providing helper Greg Kroah-Hartman
2021-03-22 12:28 ` [PATCH 4.14 14/43] perf: Make perf able to build with latest libbfd Greg Kroah-Hartman
2021-03-22 12:28 ` [PATCH 4.14 15/43] tools build feature: Check if pthread_barrier_t is available Greg Kroah-Hartman
2021-03-22 12:28 ` [PATCH 4.14 16/43] btrfs: fix race when cloning extent buffer during rewind of an old root Greg Kroah-Hartman
2021-03-22 12:28 ` [PATCH 4.14 17/43] nvmet: dont check iosqes,iocqes for discovery controllers Greg Kroah-Hartman
2021-03-22 12:28 ` [PATCH 4.14 18/43] NFSD: Repair misuse of sv_lock in 5.10.16-rt30 Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 19/43] svcrdma: disable timeouts on rdma backchannel Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 20/43] sunrpc: fix refcount leak for rpc auth modules Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 21/43] net/qrtr: fix __netdev_alloc_skb call Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 22/43] scsi: lpfc: Fix some error codes in debugfs Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 23/43] nvme-rdma: fix possible hang when failing to set io queues Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 24/43] usb-storage: Add quirk to defeat Kindles automatic unload Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 25/43] USB: replace hardcode maximum usb string length by definition Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 26/43] usb: gadget: configfs: Fix KASAN use-after-free Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 27/43] iio:adc:stm32-adc: Add HAS_IOMEM dependency Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 28/43] iio:adc:qcom-spmi-vadc: add default scale to LR_MUX2_BAT_ID channel Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 29/43] iio: adis16400: Fix an error code in adis16400_initial_setup() Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 30/43] iio: gyro: mpu3050: Fix error handling in mpu3050_trigger_handler Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 31/43] iio: hid-sensor-humidity: Fix alignment issue of timestamp channel Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 32/43] iio: hid-sensor-prox: Fix scale not correct issue Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 33/43] iio: hid-sensor-temperature: Fix issues of timestamp channel Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 34/43] PCI: rpadlpar: Fix potential drc_name corruption in store functions Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 35/43] perf/x86/intel: Fix a crash caused by zero PEBS status Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 36/43] x86/ioapic: Ignore IRQ2 again Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 37/43] kernel, fs: Introduce and use set_restart_fn() and arch_set_restart_data() Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 38/43] x86: Move TS_COMPAT back to asm/thread_info.h Greg Kroah-Hartman
2021-03-22 12:29 ` Greg Kroah-Hartman [this message]
2021-03-22 12:29 ` [PATCH 4.14 40/43] ext4: find old entry again if failed to rename whiteout Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 41/43] ext4: do not try to set xattr into ea_inode if value is empty Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 42/43] ext4: fix potential error in ext4_do_update_inode Greg Kroah-Hartman
2021-03-22 12:29 ` [PATCH 4.14 43/43] genirq: Disable interrupts for force threaded handlers Greg Kroah-Hartman
2021-03-22 14:35 ` [PATCH 4.14 00/43] 4.14.227-rc1 review Jon Hunter
2021-03-22 21:54 ` Guenter Roeck
2021-03-23 13:01 ` Naresh Kamboju
2021-03-24 0:56 ` Samuel Zou
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