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authorAndy Lutomirski <luto@kernel.org>2016-09-16 07:45:45 +0200
committerIngo Molnar <mingo@kernel.org>2016-09-16 09:18:53 +0200
commit1959a60182f48879635812a03a99c02231ea8677 (patch)
tree17a624d2b02664dcc0bd218f18b68f8f1f6cad6f /arch
parentkthread: Pin the stack via try_get_task_stack()/put_task_stack() in to_live_k... (diff)
downloadlinux-1959a60182f48879635812a03a99c02231ea8677.tar.xz
linux-1959a60182f48879635812a03a99c02231ea8677.zip
x86/dumpstack: Pin the target stack when dumping it
Specifically, pin the stack in save_stack_trace_tsk() and show_trace_log_lvl(). This will prevent a crash if the target task dies before or while dumping its stack once we start freeing task stacks early. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jann Horn <jann@thejh.net> Cc: Josh Poimboeuf <jpoimboe@redhat.com> 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/cf0082cde65d1941a996d026f2b2cdbfaca17bfa.1474003868.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/dumpstack_32.c5
-rw-r--r--arch/x86/kernel/dumpstack_64.c5
-rw-r--r--arch/x86/kernel/stacktrace.c5
3 files changed, 15 insertions, 0 deletions
diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index 2d65cfa5e0b4..122f37d7bb7e 100644
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -163,6 +163,9 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
unsigned long *stack;
int i;
+ if (!try_get_task_stack(task))
+ return;
+
sp = sp ? : get_stack_pointer(task, regs);
stack = sp;
@@ -179,6 +182,8 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
}
pr_cont("\n");
show_trace_log_lvl(task, regs, sp, bp, log_lvl);
+
+ put_task_stack(task);
}
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index 8cb6004a4dfd..16c0d5f89b5e 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -218,6 +218,9 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
unsigned long *stack;
int i;
+ if (!try_get_task_stack(task))
+ return;
+
irq_stack_end = (unsigned long *)this_cpu_read(irq_stack_ptr);
irq_stack = irq_stack_end - (IRQ_STACK_SIZE / sizeof(long));
@@ -253,6 +256,8 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
pr_cont("\n");
show_trace_log_lvl(task, regs, sp, bp, log_lvl);
+
+ put_task_stack(task);
}
void show_regs(struct pt_regs *regs)
diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c
index 785aef1c7ef5..23fa81e24c8a 100644
--- a/arch/x86/kernel/stacktrace.c
+++ b/arch/x86/kernel/stacktrace.c
@@ -79,9 +79,14 @@ void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
{
+ if (!try_get_task_stack(tsk))
+ return;
+
dump_trace(tsk, NULL, NULL, 0, &save_stack_ops_nosched, trace);
if (trace->nr_entries < trace->max_entries)
trace->entries[trace->nr_entries++] = ULONG_MAX;
+
+ put_task_stack(tsk);
}
EXPORT_SYMBOL_GPL(save_stack_trace_tsk);