linux-kernel - [PATCH 4.19 050/149] arm64: kprobe: Always blacklist the KVM world-switch code

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 12 Mar 2019 10:07:48 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Christoffer Dall <christoffer.dall@....com>,
        James Morse <james.morse@....com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Will Deacon <will.deacon@....com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 050/149] arm64: kprobe: Always blacklist the KVM world-switch code

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit f2b3d8566d81deaca31f4e3163def0bea7746e11 ]

On systems with VHE the kernel and KVM's world-switch code run at the
same exception level. Code that is only used on a VHE system does not
need to be annotated as __hyp_text as it can reside anywhere in the
 kernel text.

__hyp_text was also used to prevent kprobes from patching breakpoint
instructions into this region, as this code runs at a different
exception level. While this is no longer true with VHE, KVM still
switches VBAR_EL1, meaning a kprobe's breakpoint executed in the
world-switch code will cause a hyp-panic.

Move the __hyp_text check in the kprobes blacklist so it applies on
VHE systems too, to cover the common code and guest enter/exit
assembly.

Fixes: 888b3c8720e0 ("arm64: Treat all entry code as non-kprobe-able")
Reviewed-by: Christoffer Dall <christoffer.dall@....com>
Signed-off-by: James Morse <james.morse@....com>
Acked-by: Masami Hiramatsu <mhiramat@...nel.org>
Signed-off-by: Will Deacon <will.deacon@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/arm64/kernel/probes/kprobes.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
index b5a367d4bba6..30bb13797034 100644
--- a/arch/arm64/kernel/probes/kprobes.c
+++ b/arch/arm64/kernel/probes/kprobes.c
@@ -478,13 +478,13 @@ bool arch_within_kprobe_blacklist(unsigned long addr)
 	    addr < (unsigned long)__entry_text_end) ||
 	    (addr >= (unsigned long)__idmap_text_start &&
 	    addr < (unsigned long)__idmap_text_end) ||
+	    (addr >= (unsigned long)__hyp_text_start &&
+	    addr < (unsigned long)__hyp_text_end) ||
 	    !!search_exception_tables(addr))
 		return true;
 
 	if (!is_kernel_in_hyp_mode()) {
-		if ((addr >= (unsigned long)__hyp_text_start &&
-		    addr < (unsigned long)__hyp_text_end) ||
-		    (addr >= (unsigned long)__hyp_idmap_text_start &&
+		if ((addr >= (unsigned long)__hyp_idmap_text_start &&
 		    addr < (unsigned long)__hyp_idmap_text_end))
 			return true;
 	}
-- 
2.19.1