aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorOleg Nesterov <[email protected]>2015-03-13 09:53:09 +0100
committerIngo Molnar <[email protected]>2015-03-13 12:44:28 +0100
commita7c80ebcac3068b1c3cb27d538d29558c30010c8 (patch)
tree843cabd6aeaae3b6385ddefc5b437ef48ce7b7d4
parentc8a470cab030bae8f9e6e5cfff72b047b7c627a7 (diff)
x86/fpu: Avoid math_state_restore() without used_math() in __restore_xstate_sig()
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: <[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]>
-rw-r--r--arch/x86/kernel/xsave.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c
index 34f66e58a896..cdc6cf903078 100644
--- a/arch/x86/kernel/xsave.c
+++ b/arch/x86/kernel/xsave.c
@@ -379,7 +379,7 @@ int __restore_xstate_sig(void __user *buf, void __user *buf_fx, int size)
* 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;
@@ -393,14 +393,15 @@ int __restore_xstate_sig(void __user *buf, void __user *buf_fx, int size)
*/
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();