linux-kernel - [PATCH 3.10 142/250] MIPS: Clear ISA bit correctly in get_frame

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]

Message-Id: <1496876436-32402-143-git-send-email-w@1wt.eu>
Date:   Thu,  8 Jun 2017 00:58:48 +0200
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux@...ck-us.net
Cc:     Paul Burton <paul.burton@...tec.com>,
        Leonid Yegoshin <leonid.yegoshin@...tec.com>,
        linux-mips@...ux-mips.org, Ralf Baechle <ralf@...ux-mips.org>,
        Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 142/250] MIPS: Clear ISA bit correctly in get_frame_info()

From: Paul Burton <paul.burton@...tec.com>

commit ccaf7caf2c73c6db920772bf08bf1d47b2170634 upstream.

get_frame_info() can be called in microMIPS kernels with the ISA bit
already clear. For example this happens when unwind_stack_by_address()
is called because we begin with a PC that has the ISA bit set & subtract
the (odd) offset from the preceding symbol (which does not have the ISA
bit set). Since get_frame_info() unconditionally subtracts 1 from the PC
in microMIPS kernels it incorrectly misaligns the address it then
attempts to access code at, leading to an address error exception.

Fix this by using msk_isa16_mode() to clear the ISA bit, which allows
get_frame_info() to function regardless of whether it is provided with a
PC that has the ISA bit set or not.

Signed-off-by: Paul Burton <paul.burton@...tec.com>
Fixes: 34c2f668d0f6 ("MIPS: microMIPS: Add unaligned access support.")
Cc: Leonid Yegoshin <leonid.yegoshin@...tec.com>
Cc: linux-mips@...ux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14528/
Signed-off-by: Ralf Baechle <ralf@...ux-mips.org>
Signed-off-by: Willy Tarreau <w@....eu>
---
 arch/mips/kernel/process.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index c6a041d..11468a0 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -322,17 +322,14 @@ static inline int is_sp_move_ins(union mips_instruction *ip)
 
 static int get_frame_info(struct mips_frame_info *info)
 {
-#ifdef CONFIG_CPU_MICROMIPS
-	union mips_instruction *ip = (void *) (((char *) info->func) - 1);
-#else
-	union mips_instruction *ip = info->func;
-#endif
+	union mips_instruction *ip;
 	unsigned max_insns = info->func_size / sizeof(union mips_instruction);
 	unsigned i;
 
 	info->pc_offset = -1;
 	info->frame_size = 0;
 
+	ip = (void *)msk_isa16_mode((ulong)info->func);
 	if (!ip)
 		goto err;
 
-- 
2.8.0.rc2.1.gbe9624a