ARM: 8772/1: kprobes: Prohibit kprobes on get_user functions

Since do_undefinstr() uses get_user to get the undefined
instruction, it can be called before kprobes processes
recursive check. This can cause an infinit recursive
exception.
Prohibit probing on get_user functions.

Fixes: 24ba613c9d6c ("ARM kprobes: core code")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
index bc8d4bbd82e27719a990c7972fd77bfca9dc7aef..9342904cccca67ac3cfba4e0b75bcbc17893ade0 100644 (file)
--- a/arch/arm/include/asm/assembler.h
+++ b/arch/arm/include/asm/assembler.h
@@ -536,4 +536,14 @@ THUMB(     orr     \reg , \reg , #PSR_T_BIT        )
 #endif
        .endm
 
+#ifdef CONFIG_KPROBES
+#define _ASM_NOKPROBE(entry)                           \
+       .pushsection "_kprobe_blacklist", "aw" ;        \
+       .balign 4 ;                                     \
+       .long entry;                                    \
+       .popsection
+#else
+#define _ASM_NOKPROBE(entry)
+#endif
+
 #endif /* __ASM_ASSEMBLER_H__ */

diff --git a/arch/arm/lib/getuser.S b/arch/arm/lib/getuser.S
index df73914e81c8344feccac5df8d5791dcbe92ed60..746e7801dcdf70fed9e339c2d6800b3f275c49b7 100644 (file)
--- a/arch/arm/lib/getuser.S
+++ b/arch/arm/lib/getuser.S
@@ -38,6 +38,7 @@ ENTRY(__get_user_1)
        mov     r0, #0
        ret     lr
 ENDPROC(__get_user_1)
+_ASM_NOKPROBE(__get_user_1)
 
 ENTRY(__get_user_2)
        check_uaccess r0, 2, r1, r2, __get_user_bad
@@ -58,6 +59,7 @@ rb    .req    r0
        mov     r0, #0
        ret     lr
 ENDPROC(__get_user_2)
+_ASM_NOKPROBE(__get_user_2)
 
 ENTRY(__get_user_4)
        check_uaccess r0, 4, r1, r2, __get_user_bad
@@ -65,6 +67,7 @@ ENTRY(__get_user_4)
        mov     r0, #0
        ret     lr
 ENDPROC(__get_user_4)
+_ASM_NOKPROBE(__get_user_4)
 
 ENTRY(__get_user_8)
        check_uaccess r0, 8, r1, r2, __get_user_bad8
@@ -78,6 +81,7 @@ ENTRY(__get_user_8)
        mov     r0, #0
        ret     lr
 ENDPROC(__get_user_8)
+_ASM_NOKPROBE(__get_user_8)
 
 #ifdef __ARMEB__
 ENTRY(__get_user_32t_8)
@@ -91,6 +95,7 @@ ENTRY(__get_user_32t_8)
        mov     r0, #0
        ret     lr
 ENDPROC(__get_user_32t_8)
+_ASM_NOKPROBE(__get_user_32t_8)
 
 ENTRY(__get_user_64t_1)
        check_uaccess r0, 1, r1, r2, __get_user_bad8
@@ -98,6 +103,7 @@ ENTRY(__get_user_64t_1)
        mov     r0, #0
        ret     lr
 ENDPROC(__get_user_64t_1)
+_ASM_NOKPROBE(__get_user_64t_1)
 
 ENTRY(__get_user_64t_2)
        check_uaccess r0, 2, r1, r2, __get_user_bad8
@@ -114,6 +120,7 @@ rb  .req    r0
        mov     r0, #0
        ret     lr
 ENDPROC(__get_user_64t_2)
+_ASM_NOKPROBE(__get_user_64t_2)
 
 ENTRY(__get_user_64t_4)
        check_uaccess r0, 4, r1, r2, __get_user_bad8
@@ -121,6 +128,7 @@ ENTRY(__get_user_64t_4)
        mov     r0, #0
        ret     lr
 ENDPROC(__get_user_64t_4)
+_ASM_NOKPROBE(__get_user_64t_4)
 #endif
 
 __get_user_bad8:
@@ -131,6 +139,8 @@ __get_user_bad:
        ret     lr
 ENDPROC(__get_user_bad)
 ENDPROC(__get_user_bad8)
+_ASM_NOKPROBE(__get_user_bad)
+_ASM_NOKPROBE(__get_user_bad8)
 
 .pushsection __ex_table, "a"
        .long   1b, __get_user_bad