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x86/fpu: Use validate_xstate_header() to validate the xstate_header in __fpu__restore_sig()

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Tighten the checks in __fpu__restore_sig() and update comments.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kevin Hao <haokexin@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Halcrow <mhalcrow@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: kernel-hardening@lists.openwall.com
Link: http://lkml.kernel.org/r/20170924105913.9157-4-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Eric Biggers 2017-09-24 12:59:06 +02:00 committed by Ingo Molnar
parent cf9df81b13
commit b11e2e18a7
1 changed files with 9 additions and 7 deletions
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16
arch/x86/kernel/fpu/signal.c
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@ -214,8 +214,11 @@ sanitize_restored_xstate(struct task_struct *tsk,
struct xstate_header *header = &xsave->header;
if (use_xsave()) {
/* These bits must be zero. */
memset(header->reserved, 0, 48);
/*
* Note: we don't need to zero the reserved bits in the
* xstate_header here because we either didn't copy them at all,
* or we checked earlier that they aren't set.
*/
/*
* Init the state that is not present in the memory
@ -224,7 +227,7 @@ sanitize_restored_xstate(struct task_struct *tsk,
if (fx_only)
header->xfeatures = XFEATURE_MASK_FPSSE;
else
header->xfeatures &= (xfeatures_mask & xfeatures);
header->xfeatures &= xfeatures;
}
if (use_fxsr()) {
@ -308,7 +311,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
/*
* For 32-bit frames with fxstate, copy the user state to the
* thread's fpu state, reconstruct fxstate from the fsave
* header. Sanitize the copied state etc.
* header. Validate and sanitize the copied state.
*/
struct fpu *fpu = &tsk->thread.fpu;
struct user_i387_ia32_struct env;
@ -329,9 +332,8 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
} else {
err = __copy_from_user(&fpu->state.xsave, buf_fx, state_size);
/* xcomp_bv must be 0 when using uncompacted format */
if (!err && state_size > offsetof(struct xregs_state, header) && fpu->state.xsave.header.xcomp_bv)
err = -EINVAL;
if (!err && state_size > offsetof(struct xregs_state, header))
err = validate_xstate_header(&fpu->state.xsave.header);
}
if (err || __copy_from_user(&env, buf, sizeof(env))) {