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 3.14-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-3.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From a7c80ebcac3068b1c3cb27d538d29558c30010c8 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov <oleg@xxxxxxxxxx> 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 <oleg@xxxxxxxxxx> 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 <oleg@xxxxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxx> Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Pekka Riikonen <priikone@xxxxxx> Cc: Quentin Casasnovas <quentin.casasnovas@xxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: Suresh Siddha <sbsiddha@xxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/20150307153844.GB25954@xxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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 @@ -375,7 +375,7 @@ 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; @@ -389,14 +389,15 @@ 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 oleg@xxxxxxxxxx are queue-3.14/x86-fpu-drop_fpu-should-not-assume-that-tsk-equals-current.patch queue-3.14/x86-fpu-avoid-math_state_restore-without-used_math-in-__restore_xstate_sig.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html