This is a note to let you know that I've just added the patch titled
x86/fpu: Avoid math_state_restore() without used_math() in
__restore_xstate_sig()
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-fpu-avoid-math_state_restore-without-used_math-in-__restore_xstate_sig.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From a7c80ebcac3068b1c3cb27d538d29558c30010c8 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <[email protected]>
Date: Fri, 13 Mar 2015 09:53:09 +0100
Subject: x86/fpu: Avoid math_state_restore() without used_math() in
__restore_xstate_sig()
From: Oleg Nesterov <[email protected]>
commit a7c80ebcac3068b1c3cb27d538d29558c30010c8 upstream.
math_state_restore() assumes it is called with irqs disabled,
but this is not true if the caller is __restore_xstate_sig().
This means that if ia32_fxstate == T and __copy_from_user()
fails, __restore_xstate_sig() returns with irqs disabled too.
This triggers:
BUG: sleeping function called from invalid context at
kernel/locking/rwsem.c:41
dump_stack
___might_sleep
? _raw_spin_unlock_irqrestore
__might_sleep
down_read
? _raw_spin_unlock_irqrestore
print_vma_addr
signal_fault
sys32_rt_sigreturn
Change __restore_xstate_sig() to call set_used_math()
unconditionally. This avoids enabling and disabling interrupts
in math_state_restore(). If copy_from_user() fails, we can
simply do fpu_finit() by hand.
[ Note: this is only the first step. math_state_restore() should
not check used_math(), it should set this flag. While
init_fpu() should simply die. ]
Signed-off-by: Oleg Nesterov <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Fenghua Yu <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Pekka Riikonen <[email protected]>
Cc: Quentin Casasnovas <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Suresh Siddha <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/x86/kernel/xsave.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
--- a/arch/x86/kernel/xsave.c
+++ b/arch/x86/kernel/xsave.c
@@ -376,7 +376,7 @@ int __restore_xstate_sig(void __user *bu
* thread's fpu state, reconstruct fxstate from the fsave
* header. Sanitize the copied state etc.
*/
- struct xsave_struct *xsave = &tsk->thread.fpu.state->xsave;
+ struct fpu *fpu = &tsk->thread.fpu;
struct user_i387_ia32_struct env;
int err = 0;
@@ -390,14 +390,15 @@ int __restore_xstate_sig(void __user *bu
*/
drop_fpu(tsk);
- if (__copy_from_user(xsave, buf_fx, state_size) ||
+ if (__copy_from_user(&fpu->state->xsave, buf_fx, state_size) ||
__copy_from_user(&env, buf, sizeof(env))) {
+ fpu_finit(fpu);
err = -1;
} else {
sanitize_restored_xstate(tsk, &env, xstate_bv, fx_only);
- set_used_math();
}
+ set_used_math();
if (use_eager_fpu()) {
preempt_disable();
math_state_restore();
Patches currently in stable-queue which might be from [email protected] are
queue-3.10/x86-fpu-drop_fpu-should-not-assume-that-tsk-equals-current.patch
queue-3.10/x86-fpu-avoid-math_state_restore-without-used_math-in-__restore_xstate_sig.patch
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