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x86/ptrace: Remove set_segment_reg() implementations for current

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seg_segment_reg() should be unreachable with task == current.
Rather than confusingly trying to make it work, just explicitly
disable this case.

(regset->get is used for current in the coredump code, but the ->set
 interface is only used for ptrace, and you can't ptrace yourself.)

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2019-07-15 10:08:48 -07:00 committed by Ingo Molnar
parent 0337b7ebfc
commit 8e05f1b4f2
1 changed files with 7 additions and 12 deletions
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19
arch/x86/kernel/ptrace.c
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@ -182,6 +182,9 @@ static u16 get_segment_reg(struct task_struct *task, unsigned long offset)
static int set_segment_reg(struct task_struct *task,
unsigned long offset, u16 value)
{
if (WARN_ON_ONCE(task == current))
return -EIO;
/*
* The value argument was already truncated to 16 bits.
*/
@ -209,10 +212,7 @@ static int set_segment_reg(struct task_struct *task,
break;
case offsetof(struct user_regs_struct, gs):
if (task == current)
set_user_gs(task_pt_regs(task), value);
else
task_user_gs(task) = value;
task_user_gs(task) = value;
}
return 0;
@ -272,6 +272,9 @@ static u16 get_segment_reg(struct task_struct *task, unsigned long offset)
static int set_segment_reg(struct task_struct *task,
unsigned long offset, u16 value)
{
if (WARN_ON_ONCE(task == current))
return -EIO;
/*
* The value argument was already truncated to 16 bits.
*/
@ -281,23 +284,15 @@ static int set_segment_reg(struct task_struct *task,
switch (offset) {
case offsetof(struct user_regs_struct,fs):
task->thread.fsindex = value;
if (task == current)
loadsegment(fs, task->thread.fsindex);
break;
case offsetof(struct user_regs_struct,gs):
task->thread.gsindex = value;
if (task == current)
load_gs_index(task->thread.gsindex);
break;
case offsetof(struct user_regs_struct,ds):
task->thread.ds = value;
if (task == current)
loadsegment(ds, task->thread.ds);
break;
case offsetof(struct user_regs_struct,es):
task->thread.es = value;
if (task == current)
loadsegment(es, task->thread.es);
break;
/*