From: Peter Zijlstra <peterz@infradead.org>
To: torvalds@linux-foundation.org, tglx@linutronix.de, hpa@zytor.com,
julien.thierry@arm.com, will.deacon@arm.com, luto@amacapital.net,
mingo@kernel.org, catalin.marinas@arm.com, james.morse@arm.com,
valentin.schneider@arm.com, brgerst@gmail.com,
jpoimboe@redhat.com, luto@kernel.org, bp@alien8.de,
dvlasenk@redhat.com
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org
Subject: [PATCH 2/6] x86/ia32: Fix ia32_restore_sigcontext AC leak
Date: Mon, 25 Feb 2019 13:43:32 +0100 [thread overview]
Message-ID: <20190225125231.936952143@infradead.org> (raw)
In-Reply-To: 20190225124330.613028745@infradead.org
Don't call load_gs_index() with AC set; delay the segment setting
until after the AC section.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/ia32/ia32_signal.c | 29 +++++++++++++++++++----------
1 file changed, 19 insertions(+), 10 deletions(-)
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -60,17 +60,21 @@
regs->seg = GET_SEG(seg) | 3; \
} while (0)
-#define RELOAD_SEG(seg) { \
- unsigned int pre = GET_SEG(seg); \
- unsigned int cur = get_user_seg(seg); \
- pre |= 3; \
- if (pre != cur) \
- set_user_seg(seg, pre); \
+#define LOAD_SEG(seg) { \
+ pre_##seg = 3 | GET_SEG(seg); \
+ cur_##seg = get_user_seg(seg); \
+}
+
+#define RELOAD_SEG(seg) { \
+ if (pre_##seg != cur_##seg) \
+ set_user_seg(seg, pre_##seg); \
}
static int ia32_restore_sigcontext(struct pt_regs *regs,
struct sigcontext_32 __user *sc)
{
+ u16 pre_gs, pre_fs, pre_ds, pre_es;
+ u16 cur_gs, cur_fs, cur_ds, cur_es;
unsigned int tmpflags, err = 0;
void __user *buf;
u32 tmp;
@@ -85,10 +89,10 @@ static int ia32_restore_sigcontext(struc
* 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);
+ LOAD_SEG(gs);
+ LOAD_SEG(fs);
+ LOAD_SEG(ds);
+ LOAD_SEG(es);
COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
COPY(dx); COPY(cx); COPY(ip); COPY(ax);
@@ -106,6 +110,11 @@ static int ia32_restore_sigcontext(struc
buf = compat_ptr(tmp);
} get_user_catch(err);
+ RELOAD_SEG(gs);
+ RELOAD_SEG(fs);
+ RELOAD_SEG(ds);
+ RELOAD_SEG(es);
+
err |= fpu__restore_sig(buf, 1);
force_iret();
next prev parent reply other threads:[~2019-02-25 12:53 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-25 12:43 [PATCH 0/6] objtool: UACCESS validation Peter Zijlstra
2019-02-25 12:43 ` [PATCH 1/6] x86/uaccess: Dont evaluate argument inside AC region Peter Zijlstra
2019-02-25 15:43 ` Andy Lutomirski
2019-02-25 16:02 ` Peter Zijlstra
2019-02-25 16:36 ` Borislav Petkov
2019-02-25 16:50 ` Andy Lutomirski
2019-02-25 19:09 ` Linus Torvalds
2019-02-25 19:18 ` Borislav Petkov
2019-02-25 18:10 ` [tip:x86/urgent] x86/uaccess: Don't leak the AC flag into __put_user() value evaluation tip-bot for Andy Lutomirski
2019-02-25 19:46 ` tip-bot for Andy Lutomirski
2019-02-25 12:43 ` Peter Zijlstra [this message]
2019-02-25 15:41 ` [PATCH 2/6] x86/ia32: Fix ia32_restore_sigcontext AC leak Andy Lutomirski
2019-02-25 16:10 ` Peter Zijlstra
2019-02-25 16:29 ` Andy Lutomirski
2019-02-25 16:37 ` Peter Zijlstra
2019-02-25 16:41 ` Peter Zijlstra
2019-02-25 16:49 ` Andy Lutomirski
2019-02-25 12:43 ` [PATCH 3/6] objtool: Set insn->func for alternatives Peter Zijlstra
2019-02-25 12:43 ` [PATCH 4/6] objtool: Replace STACK_FRAME_NON_STANDARD annotation Peter Zijlstra
2019-02-25 16:11 ` Josh Poimboeuf
2019-02-25 16:17 ` Peter Zijlstra
2019-02-25 16:23 ` Josh Poimboeuf
2019-02-27 12:20 ` Peter Zijlstra
2019-02-28 0:30 ` Andy Lutomirski
2019-02-25 12:43 ` [PATCH 5/6] objtool: Add UACCESS validation Peter Zijlstra
2019-02-25 15:53 ` Andy Lutomirski
2019-02-25 16:12 ` Peter Zijlstra
2019-02-25 17:15 ` Peter Zijlstra
2019-02-25 17:34 ` Linus Torvalds
2019-02-25 17:38 ` Josh Poimboeuf
2019-02-27 14:08 ` Peter Zijlstra
2019-02-27 14:17 ` Andrey Ryabinin
2019-02-27 14:26 ` Peter Zijlstra
2019-02-27 14:33 ` Peter Zijlstra
2019-02-27 15:40 ` Dmitry Vyukov
2019-02-27 17:28 ` Peter Zijlstra
2019-02-28 9:40 ` Peter Zijlstra
2019-02-28 9:59 ` Dmitry Vyukov
2019-02-28 10:05 ` Dmitry Vyukov
2019-02-28 10:52 ` Peter Zijlstra
2019-02-27 16:18 ` Linus Torvalds
2019-02-27 17:30 ` Peter Zijlstra
2019-02-27 17:36 ` Linus Torvalds
2019-02-25 12:43 ` [PATCH 6/6] objtool: Add Direction Flag validation Peter Zijlstra
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