Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1738250
| From | Eric Biggers <ebiggers3@gmail.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 03/10] x86/fpu: Use validate_xstate_header() to validate the xstate_header in sanitize_restored_xstate() |
| Date | 2017-09-24 21:00 +0200 |
| Message-ID | <utkid-3NE-13@gated-at.bofh.it> (permalink) |
| References | <utcNH-7Gh-3@gated-at.bofh.it> <utcXo-7Yz-9@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Sun, Sep 24, 2017 at 12:59:06PM +0200, Ingo Molnar wrote:
> @@ -328,10 +331,8 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
> err = copy_user_to_xstate(&fpu->state.xsave, buf_fx);
> } else {
> err = __copy_from_user(&fpu->state.xsave, buf_fx, state_size);
> -
> - /* xcomp_bv must be 0 when using uncompacted format */
> - if (!err && fpu->state.xsave.header.xcomp_bv)
> - err = -EINVAL;
> + if (!err)
> + err = validate_xstate_header(&fpu->state.xsave.header);
> }
>
Sorry, this is the buggy part. The problem is that this code runs even if XSAVE
isn't being used --- and in that case the state size is 512 bytes or less, so
the state doesn't actually include the xstate_header. So
validate_xstate_header() was reading out of bounds and seeing invalid values.
So I think we need to check use_xsave() here, but it really needs to be in the
earlier patch which added the check for just ->xcomp_bv ("x86/fpu: Don't let
userspace set bogus xcomp_bv"), not in this one.
As far the split of patch 2/3 into these 10 patches, it looks fine (though it
suddenly became a *lot* of patches!). One nit: the subject of this one really
should say "__fpu__restore_sig()", not "sanitize_restored_xstate()".
I can send a fixed series when I have a chance.
Eric
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[PATCH 00/10] x86/fpu: Split up "x86/fpu: Tighten validation of user-supplied xstate_header" Ingo Molnar <mingo@kernel.org> - 2017-09-24 13:00 +0200
[PATCH 02/10] x86/fpu: Use validate_xstate_header() to validate the xstate_header in xstateregs_set() Ingo Molnar <mingo@kernel.org> - 2017-09-24 13:00 +0200
[tip:x86/fpu] x86/fpu: Use validate_xstate_header() to validate the xstate_header in xstateregs_set() tip-bot for Eric Biggers <tipbot@zytor.com> - 2017-09-26 10:50 +0200
[PATCH 09/10] x86/fpu: Use validate_xstate_header() to validate the xstate_header in copy_user_to_xstate() Ingo Molnar <mingo@kernel.org> - 2017-09-24 13:00 +0200
[tip:x86/fpu] x86/fpu: Use validate_xstate_header() to validate the xstate_header in copy_user_to_xstate() tip-bot for Eric Biggers <tipbot@zytor.com> - 2017-09-26 10:50 +0200
[PATCH 10/10] x86/fpu: Use using_compacted_format() instead of open coded X86_FEATURE_XSAVES Ingo Molnar <mingo@kernel.org> - 2017-09-24 13:10 +0200
[tip:x86/fpu] x86/fpu: Use using_compacted_format() instead of open coded X86_FEATURE_XSAVES tip-bot for Eric Biggers <tipbot@zytor.com> - 2017-09-26 10:50 +0200
[PATCH 03/10] x86/fpu: Use validate_xstate_header() to validate the xstate_header in sanitize_restored_xstate() Ingo Molnar <mingo@kernel.org> - 2017-09-24 13:10 +0200
Re: [PATCH 03/10] x86/fpu: Use validate_xstate_header() to validate the xstate_header in sanitize_restored_xstate() Eric Biggers <ebiggers3@gmail.com> - 2017-09-24 21:00 +0200
Re: [PATCH 03/10] x86/fpu: Use validate_xstate_header() to validate the xstate_header in sanitize_restored_xstate() Ingo Molnar <mingo@kernel.org> - 2017-09-24 21:10 +0200
Re: [PATCH 03/10] x86/fpu: Use validate_xstate_header() to validate the xstate_header in sanitize_restored_xstate() Eric Biggers <ebiggers3@gmail.com> - 2017-09-24 22:10 +0200
Re: [PATCH 03/10] x86/fpu: Use validate_xstate_header() to validate the xstate_header in sanitize_restored_xstate() Ingo Molnar <mingo@kernel.org> - 2017-09-25 08:10 +0200
Re: [PATCH 03/10] x86/fpu: Use validate_xstate_header() to validate the xstate_header in sanitize_restored_xstate() Ingo Molnar <mingo@kernel.org> - 2017-09-25 08:20 +0200
Re: [PATCH 03/10] x86/fpu: Use validate_xstate_header() to validate the xstate_header in sanitize_restored_xstate() Eric Biggers <ebiggers3@gmail.com> - 2017-09-25 09:30 +0200
Re: [PATCH 03/10] x86/fpu: Use validate_xstate_header() to validate the xstate_header in sanitize_restored_xstate() Ingo Molnar <mingo@kernel.org> - 2017-09-25 09:40 +0200
[tip:x86/fpu] x86/fpu: Use validate_xstate_header() to validate the xstate_header in __fpu__restore_sig() tip-bot for Eric Biggers <tipbot@zytor.com> - 2017-09-26 10:50 +0200
[PATCH 07/10] x86/fpu: Copy the full header in copy_user_to_xstate() Ingo Molnar <mingo@kernel.org> - 2017-09-24 13:10 +0200
[tip:x86/fpu] x86/fpu: Copy the full header in copy_user_to_xstate() tip-bot for Eric Biggers <tipbot@zytor.com> - 2017-09-26 10:50 +0200
[PATCH 01/10] x86/fpu: Introduce validate_xstate_header() Ingo Molnar <mingo@kernel.org> - 2017-09-24 13:10 +0200
[tip:x86/fpu] x86/fpu: Introduce validate_xstate_header() tip-bot for Eric Biggers <tipbot@zytor.com> - 2017-09-26 10:50 +0200
[PATCH 08/10] x86/fpu: Eliminate the 'xfeatures' local variable in copy_user_to_xstate() Ingo Molnar <mingo@kernel.org> - 2017-09-24 13:10 +0200
[tip:x86/fpu] x86/fpu: Eliminate the 'xfeatures' local variable in copy_user_to_xstate() tip-bot for Eric Biggers <tipbot@zytor.com> - 2017-09-26 10:50 +0200
[PATCH 04/10] x86/fpu: Copy the full state_header in copy_kernel_to_xstate() Ingo Molnar <mingo@kernel.org> - 2017-09-24 13:10 +0200
[tip:x86/fpu] x86/fpu: Copy the full state_header in copy_kernel_to_xstate() tip-bot for Eric Biggers <tipbot@zytor.com> - 2017-09-26 10:50 +0200
[PATCH 06/10] x86/fpu: Use validate_xstate_header() to validate the xstate_header in copy_kernel_to_xstate() Ingo Molnar <mingo@kernel.org> - 2017-09-24 13:10 +0200
[tip:x86/fpu] x86/fpu: Use validate_xstate_header() to validate the xstate_header in copy_kernel_to_xstate() tip-bot for Eric Biggers <tipbot@zytor.com> - 2017-09-26 10:50 +0200
Re: [PATCH 00/10] x86/fpu: Split up "x86/fpu: Tighten validation of user-supplied xstate_header" Linus Torvalds <torvalds@linux-foundation.org> - 2017-09-24 20:10 +0200
Re: [PATCH 00/10] x86/fpu: Split up "x86/fpu: Tighten validation of user-supplied xstate_header" Ingo Molnar <mingo@kernel.org> - 2017-09-24 21:10 +0200
csiph-web