linux-kernel - [PATCH 2/2] x86/unwind/orc: Fix address check size for deref_stack_iret

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Message-Id: <1649749204-186363-2-git-send-email-dmtrmonakhov@yandex-team.ru>
Date:   Tue, 12 Apr 2022 10:40:04 +0300
From:   Dmitry Monakhov <dmtrmonakhov@...dex-team.ru>
To:     linux-kernel@...r.kernel.org
Cc:     x86@...nel.org, mingo@...hat.com,
        Dmitry Monakhov <dmtrmonakhov@...dex-team.ru>
Subject: [PATCH 2/2] x86/unwind/orc: Fix address check size for deref_stack_iret_regs

For historical reasons we check only IRET_FRAME_OFFSET, but this check
is no longer valid because  we also access regs->sp field which is
located beyond IRET_FRAME, so it is reasonable to validate full structure.

Signed-off-by: Dmitry Monakhov <dmtrmonakhov@...dex-team.ru>
---
 arch/x86/kernel/unwind_orc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index 80b878772b86..a249ecabe689 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -379,7 +379,7 @@ static bool deref_stack_iret_regs(struct unwind_state *state, unsigned long addr
 {
 	struct pt_regs *regs = (void *)addr - IRET_FRAME_OFFSET;
 
-	if (!stack_access_ok(state, addr, IRET_FRAME_SIZE))
+	if (!stack_access_ok(state, addr, sizeof(struct pt_regs)))
 		return false;
 
 	*ip = READ_ONCE_NOCHECK(regs->ip);
-- 
2.7.4