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x86/ia32: Fix ia32_restore_sigcontext() AC leak

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[ Upstream commit 67a0514afd ]

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

Signed-off-by: Peter 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: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Peter Zijlstra
2019-02-25 12:56:35 +01:00
committed by Chris
parent f802d39904
commit d8c045b42b
1 changed files with 17 additions and 12 deletions
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29
arch/x86/ia32/ia32_signal.c
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@@ -60,9 +60,8 @@
} 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); \
}
@@ -71,6 +70,7 @@ 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;
@@ -78,16 +78,10 @@ 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);
@@ -105,6 +99,17 @@ 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();