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Commit 5007453c authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Greg Kroah-Hartman
Browse files

x86/ia32: Fix ia32_restore_sigcontext() AC leak 



[ Upstream commit 67a0514afdbb8b2fc70b771b8c77661a9cb9d3a9 ]

Objtool spotted that we call native_load_gs_index() with AC set.
Re-arrange the code to avoid that.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 4614b0bb

arch/x86/ia32/ia32_signal.c

+17 −12
Original line number Diff line number Diff line
@@ -61,9 +61,8 @@ 
} while (0)



#define RELOAD_SEG(seg)		{		\

	unsigned int pre = GET_SEG(seg);	\

	unsigned int pre = (seg) | 3;		\

	unsigned int cur = get_user_seg(seg);	\

	pre |= 3;				\

	if (pre != cur)				\

		set_user_seg(seg, pre);		\

}
@@ -72,6 +71,7 @@ static int ia32_restore_sigcontext(struct pt_regs *regs, 
				   struct sigcontext_32 __user *sc)

{

	unsigned int tmpflags, err = 0;

	u16 gs, fs, es, ds;

	void __user *buf;

	u32 tmp;
@@ -79,16 +79,10 @@ static int ia32_restore_sigcontext(struct pt_regs *regs, 
	current->restart_block.fn = do_no_restart_syscall;



	get_user_try {

		/*

		 * Reload fs and gs if they have changed in the signal

		 * handler.  This does not handle long fs/gs base changes in

		 * the handler, but does not clobber them at least in the

		 * normal case.

		 */

		RELOAD_SEG(gs);

		RELOAD_SEG(fs);

		RELOAD_SEG(ds);

		RELOAD_SEG(es);

		gs = GET_SEG(gs);

		fs = GET_SEG(fs);

		ds = GET_SEG(ds);

		es = GET_SEG(es);



		COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);

		COPY(dx); COPY(cx); COPY(ip); COPY(ax);
@@ -106,6 +100,17 @@ static int ia32_restore_sigcontext(struct pt_regs *regs, 
		buf = compat_ptr(tmp);

	} get_user_catch(err);



	/*

	 * Reload fs and gs if they have changed in the signal

	 * handler.  This does not handle long fs/gs base changes in

	 * the handler, but does not clobber them at least in the

	 * normal case.

	 */

	RELOAD_SEG(gs);

	RELOAD_SEG(fs);

	RELOAD_SEG(ds);

	RELOAD_SEG(es);



	err |= fpu__restore_sig(buf, 1);



	force_iret();