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Groups > linux.kernel > #1739695

[tip:x86/fpu] x86/fpu: Change 'size_total' parameter to unsigned and standardize the size checks in copy_xstate_to_*()

From tip-bot for Ingo Molnar <tipbot@zytor.com>
Newsgroups linux.kernel
Subject [tip:x86/fpu] x86/fpu: Change 'size_total' parameter to unsigned and standardize the size checks in copy_xstate_to_*()
Date 2017-09-26 10:40 +0200
Message-ID <utTzn-2jm-89@gated-at.bofh.it> (permalink)
References <usSlZ-3wU-43@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Commit-ID:  6ff15f8db7eaf29ef5ead6afbec9b25485fe8703
Gitweb:     http://git.kernel.org/tip/6ff15f8db7eaf29ef5ead6afbec9b25485fe8703
Author:     Ingo Molnar <mingo@kernel.org>
AuthorDate: Sat, 23 Sep 2017 14:59:52 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Sun, 24 Sep 2017 13:04:32 +0200

x86/fpu: Change 'size_total' parameter to unsigned and standardize the size checks in copy_xstate_to_*()

'size_total' is derived from an unsigned input parameter - and then converted
to 'int' and checked for negative ranges:

	if (size_total < 0 || offset < size_total) {

This conversion and the checks are unnecessary obfuscation, reject overly
large requested copy sizes outright and simplify the underlying code.

Reported-by: Rik van Riel <riel@redhat.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: Eric Biggers <ebiggers3@gmail.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/20170923130016.21448-10-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/fpu/xstate.c | 32 +++++++++++++++-----------------
 1 file changed, 15 insertions(+), 17 deletions(-)

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index c130835..b18c545 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -925,15 +925,11 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
  * the source data pointer or increment pos, count, kbuf, and ubuf.
  */
 static inline int
-__copy_xstate_to_kernel(void *kbuf,
-			const void *data,
-			unsigned int offset, unsigned int size, int size_total)
+__copy_xstate_to_kernel(void *kbuf, const void *data,
+			unsigned int offset, unsigned int size, unsigned int size_total)
 {
-	if (!size)
-		return 0;
-
-	if (size_total < 0 || offset < size_total) {
-		unsigned int copy = size_total < 0 ? size : min(size, size_total - offset);
+	if (offset < size_total) {
+		unsigned int copy = min(size, size_total - offset);
 
 		memcpy(kbuf + offset, data, copy);
 	}
@@ -986,12 +982,13 @@ int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int of
 			offset = xstate_offsets[i];
 			size = xstate_sizes[i];
 
+			/* The next component has to fit fully into the output buffer: */
+			if (offset + size > size_total)
+				break;
+
 			ret = __copy_xstate_to_kernel(kbuf, src, offset, size, size_total);
 			if (ret)
 				return ret;
-
-			if (offset + size >= size_total)
-				break;
 		}
 
 	}
@@ -1010,13 +1007,13 @@ int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int of
 }
 
 static inline int
-__copy_xstate_to_user(void __user *ubuf, const void *data, unsigned int offset, unsigned int size, int size_total)
+__copy_xstate_to_user(void __user *ubuf, const void *data, unsigned int offset, unsigned int size, unsigned int size_total)
 {
 	if (!size)
 		return 0;
 
-	if (size_total < 0 || offset < size_total) {
-		unsigned int copy = size_total < 0 ? size : min(size, size_total - offset);
+	if (offset < size_total) {
+		unsigned int copy = min(size, size_total - offset);
 
 		if (__copy_to_user(ubuf + offset, data, copy))
 			return -EFAULT;
@@ -1069,12 +1066,13 @@ int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned i
 			offset = xstate_offsets[i];
 			size = xstate_sizes[i];
 
+			/* The next component has to fit fully into the output buffer: */
+			if (offset + size > size_total)
+				break;
+
 			ret = __copy_xstate_to_user(ubuf, src, offset, size, size_total);
 			if (ret)
 				return ret;
-
-			if (offset + size >= size_total)
-				break;
 		}
 
 	}

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Thread

[PATCH 00/33] x86 FPU fixes and cleanups for v4.14 Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
  [PATCH 19/33] x86/fpu: Decouple fpregs_activate()/fpregs_deactivate() from fpu->fpregs_active Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Decouple  fpregs_activate()/fpregs_deactivate() from fpu->fpregs_active tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 15/33] x86/fpu: Simplify fpu->fpregs_active use Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Simplify fpu->fpregs_active use tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 26/33] x86/fpu: Reinitialize FPU registers if restoring FPU state fails Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Reinitialize FPU registers if restoring FPU  state fails tip-bot for Eric Biggers <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 32/33] x86/fpu: Rename fpu__activate_curr() to fpu__initialize() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Rename fpu__activate_curr() to  fpu__initialize() tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:50 +0200
  [PATCH 31/33] x86/fpu: Simplify and speed up fpu__copy() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Simplify and speed up fpu__copy() tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:50 +0200
  [PATCH 21/33] x86/fpu: Add FPU state copying quirk to handle XRSTOR failure on Intel Skylake CPUs Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Add FPU state copying quirk to handle XRSTOR  failure on Intel Skylake CPUs tip-bot for Rik van Riel <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 13/33] x86/fpu: Remove 'kbuf' parameter from the copy_user_to_xstate() API Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Remove 'kbuf' parameter from the  copy_user_to_xstate() API tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 33/33] x86/fpu: Rename fpu__activate_fpstate_read/write() to fpu__read/write() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
  [PATCH 02/33] x86/fpu: Split copy_xstate_to_user() into copy_xstate_to_kernel() & copy_xstate_to_user() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Split copy_xstate_to_user() into  copy_xstate_to_kernel() & copy_xstate_to_user() tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:30 +0200
  [PATCH 16/33] x86/fpu: Make the fpu state change in fpu__clear() scheduler-atomic Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Make the fpu state change in fpu__clear()  scheduler-atomic tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 14/33] x86/fpu: Flip the parameter order in copy_*_to_xstate() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Flip the parameter order in  copy_*_to_xstate() tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 11/33] x86/fpu: Split copy_user_to_xstate() into copy_kernel_to_xstate() & copy_user_to_xstate() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Split copy_user_to_xstate() into  copy_kernel_to_xstate() & copy_user_to_xstate() tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 07/33] x86/fpu: Remove the 'start_pos' parameter from the __copy_xstate_to_*() functions Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Remove the 'start_pos' parameter from the  __copy_xstate_to_*() functions tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 01/33] x86/fpu: Rename copyin_to_xsaves()/copyout_from_xsaves() to copy_user_to_xstate()/copy_xstate_to_user() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Rename  copyin_to_xsaves()/copyout_from_xsaves() to  copy_user_to_xstate()/copy_xstate_to_user() tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:30 +0200
  [PATCH 29/33] x86/fpu: Rename fpu::fpstate_active to fpu::initialized Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Rename fpu::fpstate_active to  fpu::initialized tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:50 +0200
  [PATCH 17/33] x86/fpu: Split the state handling in fpu__drop() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Split the state handling in fpu__drop() tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 09/33] x86/fpu: Change 'size_total' parameter to unsigned and standardize the size checks in copy_xstate_to_*() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Change 'size_total' parameter to unsigned  and standardize the size checks in copy_xstate_to_*() tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 30/33] x86/fpu: Fix stale comments about lazy FPU logic Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Fix stale comments about lazy FPU logic tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:50 +0200
  [PATCH 08/33] x86/fpu: Clarify parameter names in the copy_xstate_to_*() methods Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    Re: [PATCH 08/33] x86/fpu: Clarify parameter names in the  copy_xstate_to_*() methods Thomas Gleixner <tglx@linutronix.de> - 2017-09-25 22:00 +0200
      Re: [PATCH 08/33] x86/fpu: Clarify parameter names in the  copy_xstate_to_*() methods Thomas Gleixner <tglx@linutronix.de> - 2017-09-25 22:10 +0200
    [tip:x86/fpu] x86/fpu: Clarify parameter names in the  copy_xstate_to_*() methods tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 20/33] x86/fpu: Remove struct fpu::fpregs_active Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Remove struct fpu::fpregs_active tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 03/33] x86/fpu: Remove 'ubuf' parameter from the copy_xstate_to_kernel() APIs Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Remove 'ubuf' parameter from the  copy_xstate_to_kernel() APIs tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:30 +0200
  [PATCH 23/33] x86/fpu: Turn WARN_ON() in context switch into WARN_ON_FPU() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Turn WARN_ON() in context switch into  WARN_ON_FPU() tip-bot for Andi Kleen <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 22/33] x86/fpu: Fix boolreturn.cocci warnings Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Fix boolreturn.cocci warnings tip-bot for kbuild test robot <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 06/33] x86/fpu: Clean up the parameter definitions of copy_xstate_to_*() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Clean up the parameter definitions of  copy_xstate_to_*() tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 04/33] x86/fpu: Remove 'kbuf' parameter from the copy_xstate_to_user() APIs Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Remove 'kbuf' parameter from the  copy_xstate_to_user() APIs tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 05/33] x86/fpu: Clean up parameter order in the copy_xstate_to_*() APIs Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Clean up parameter order in the  copy_xstate_to_*() APIs tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 24/33] x86/fpu: Don't let userspace set bogus xcomp_bv Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Don't let userspace set bogus xcomp_bv tip-bot for Eric Biggers <tipbot@zytor.com> - 2017-09-26 10:50 +0200
  [PATCH 18/33] x86/fpu: Change fpu->fpregs_active users to fpu->fpstate_active Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Change fpu->fpregs_active users to  fpu->fpstate_active tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 27/33] x86/fpu: Simplify fpu__activate_fpstate_read() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Fix fpu__activate_fpstate_read() and update  comments tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 12/33] x86/fpu: Remove 'ubuf' parameter from the copy_kernel_to_xstate() API Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Remove 'ubuf' parameter from the  copy_kernel_to_xstate() API tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 25/33] x86/fpu: Tighten validation of user-supplied xstate_header Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
  [PATCH 28/33] x86/fpu: Remove fpu__current_fpstate_write_begin/end() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Remove  fpu__current_fpstate_write_begin/end() tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  Re: [PATCH 00/33] x86 FPU fixes and cleanups for v4.14 Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    Re: [PATCH 00/33] x86 FPU fixes and cleanups for v4.14 Juergen Gross <jgross@suse.com> - 2017-09-23 17:10 +0200
      Re: [PATCH 00/33] x86 FPU fixes and cleanups for v4.14 Ingo Molnar <mingo@kernel.org> - 2017-09-24 01:30 +0200

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