From: Tony Luck <tony.luck@intel.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Jue Wang <juew@google.com>, Ding Hui <dinghui@sangfor.com.cn>,
naoya.horiguchi@nec.com, osalvador@suse.de,
Youquan Song <youquan.song@intel.com>,
huangcun@sangfor.com.cn, x86@kernel.org,
linux-edac@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Tony Luck <tony.luck@intel.com>
Subject: [PATCH v2 2/3] x86/mce: Change to not send SIGBUS error during copy from user
Date: Tue, 17 Aug 2021 17:29:41 -0700 [thread overview]
Message-ID: <20210818002942.1607544-3-tony.luck@intel.com> (raw)
In-Reply-To: <20210818002942.1607544-1-tony.luck@intel.com>
Sending a SIGBUS for a copy from user is not the correct semantic.
System calls should return -EFAULT (or a short count for write(2)).
Signed-off-by: Tony Luck <tony.luck@intel.com>
---
arch/x86/kernel/cpu/mce/core.c | 35 +++++++++++++++++++---------------
1 file changed, 20 insertions(+), 15 deletions(-)
diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 94830ee9581c..957ec60cd2a8 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1269,7 +1269,7 @@ static void kill_me_maybe(struct callback_head *cb)
flags |= MF_MUST_KILL;
ret = memory_failure(p->mce_addr >> PAGE_SHIFT, flags);
- if (!ret && !(p->mce_kflags & MCE_IN_KERNEL_COPYIN)) {
+ if (!ret) {
set_mce_nospec(p->mce_addr >> PAGE_SHIFT, p->mce_whole_page);
sync_core();
return;
@@ -1283,15 +1283,21 @@ static void kill_me_maybe(struct callback_head *cb)
if (ret == -EHWPOISON)
return;
- if (p->mce_vaddr != (void __user *)-1l) {
- force_sig_mceerr(BUS_MCEERR_AR, p->mce_vaddr, PAGE_SHIFT);
- } else {
- pr_err("Memory error not recovered");
- kill_me_now(cb);
- }
+ pr_err("Memory error not recovered");
+ kill_me_now(cb);
+}
+
+static void kill_me_never(struct callback_head *cb)
+{
+ struct task_struct *p = container_of(cb, struct task_struct, mce_kill_me);
+
+ p->mce_count = 0;
+ pr_err("Kernel accessed poison in user space at %llx\n", p->mce_addr);
+ if (!memory_failure(p->mce_addr >> PAGE_SHIFT, 0))
+ set_mce_nospec(p->mce_addr >> PAGE_SHIFT, p->mce_whole_page);
}
-static void queue_task_work(struct mce *m, char *msg, int kill_current_task)
+static void queue_task_work(struct mce *m, char *msg, void (*func)(struct callback_head *))
{
int count = ++current->mce_count;
@@ -1301,11 +1307,7 @@ static void queue_task_work(struct mce *m, char *msg, int kill_current_task)
current->mce_kflags = m->kflags;
current->mce_ripv = !!(m->mcgstatus & MCG_STATUS_RIPV);
current->mce_whole_page = whole_page(m);
-
- if (kill_current_task)
- current->mce_kill_me.func = kill_me_now;
- else
- current->mce_kill_me.func = kill_me_maybe;
+ current->mce_kill_me.func = func;
}
/* Ten is likley overkill. Don't expect more than two faults before task_work() */
@@ -1456,7 +1458,10 @@ noinstr void do_machine_check(struct pt_regs *regs)
/* If this triggers there is no way to recover. Die hard. */
BUG_ON(!on_thread_stack() || !user_mode(regs));
- queue_task_work(&m, msg, kill_current_task);
+ if (kill_current_task)
+ queue_task_work(&m, msg, kill_me_now);
+ else
+ queue_task_work(&m, msg, kill_me_maybe);
} else {
/*
@@ -1474,7 +1479,7 @@ noinstr void do_machine_check(struct pt_regs *regs)
}
if (m.kflags & MCE_IN_KERNEL_COPYIN)
- queue_task_work(&m, msg, kill_current_task);
+ queue_task_work(&m, msg, kill_me_never);
}
out:
mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);
--
2.29.2
next prev parent reply other threads:[~2021-08-18 0:30 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-06 19:06 [PATCH 0/3] More machine check recovery fixes Tony Luck
2021-07-06 19:06 ` [PATCH 1/3] x86/mce: Change to not send SIGBUS error during copy from user Tony Luck
2021-07-06 19:06 ` [PATCH 2/3] x86/mce: Avoid infinite loop for copy from user recovery Tony Luck
2021-07-06 19:06 ` [PATCH 3/3] x86/mce: Drop copyin special case for #MC Tony Luck
2021-08-18 0:29 ` [PATCH v2 0/3] More machine check recovery fixes Tony Luck
2021-08-18 0:29 ` [PATCH v2 1/3] x86/mce: Avoid infinite loop for copy from user recovery Tony Luck
2021-08-20 17:31 ` Borislav Petkov
2021-08-20 18:59 ` Luck, Tony
2021-08-20 19:27 ` Borislav Petkov
2021-08-20 20:23 ` Luck, Tony
2021-08-21 4:51 ` Tony Luck
2021-08-21 21:51 ` Al Viro
2021-08-22 14:36 ` Borislav Petkov
2021-08-20 20:33 ` Luck, Tony
2021-08-22 14:46 ` Borislav Petkov
2021-08-23 15:24 ` Luck, Tony
2021-09-13 9:24 ` Borislav Petkov
2021-09-13 21:52 ` [PATCH v3] " Luck, Tony
2021-09-14 8:28 ` Borislav Petkov
2021-08-18 0:29 ` Tony Luck [this message]
2021-09-21 7:52 ` [tip: ras/core] x86/mce: Change to not send SIGBUS error during copy from user tip-bot2 for Tony Luck
2021-08-18 0:29 ` [PATCH v2 3/3] x86/mce: Drop copyin special case for #MC Tony Luck
2021-09-20 9:13 ` Borislav Petkov
2021-09-20 16:18 ` Luck, Tony
2021-09-20 16:37 ` Borislav Petkov
2021-09-20 16:43 ` Luck, Tony
2021-09-21 7:52 ` [tip: ras/core] " tip-bot2 for Tony Luck
2021-08-18 16:14 ` [PATCH v2 0/3] More machine check recovery fixes Luck, Tony
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