[3/3] powerpc/mm: Mark __init memory no-execute when STRICT_KERNEL_RWX=y

Submitted by Michael Ellerman on July 14, 2017, 6:51 a.m.

Details

Message ID 1500015083-23511-3-git-send-email-mpe@ellerman.id.au
State Accepted
Commit 029d9252b116fa52a95150819e62af1f6e420fe5
Headers show

Commit Message

Michael Ellerman July 14, 2017, 6:51 a.m.
Currently even with STRICT_KERNEL_RWX we leave the __init text marked
executable after init, which is bad.

Add a hook to mark it NX (no-execute) before we free it, and implement
it for radix and hash.

Note that we use __init_end as the end address, not _einittext,
because overlaps_kernel_text() uses __init_end, because there are
additional executable sections other than .init.text between
__init_begin and __init_end.

Tested on radix and hash with:

  0:mon> p $__init_begin
  *** 400 exception occurred

Fixes: 1e0fc9d1eb2b ("powerpc/Kconfig: Enable STRICT_KERNEL_RWX for some configs")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
 arch/powerpc/include/asm/book3s/64/hash.h    |  1 +
 arch/powerpc/include/asm/book3s/64/pgtable.h |  7 +++++++
 arch/powerpc/include/asm/book3s/64/radix.h   |  1 +
 arch/powerpc/mm/mem.c                        |  1 +
 arch/powerpc/mm/pgtable-hash64.c             | 12 ++++++++++++
 arch/powerpc/mm/pgtable-radix.c              |  8 ++++++++
 arch/powerpc/mm/pgtable_64.c                 |  8 ++++++++
 7 files changed, 38 insertions(+)

Comments

kbuild test robot July 14, 2017, 11:01 p.m.
Hi Michael,

[auto build test ERROR on powerpc/next]
[also build test ERROR on next-20170714]
[cannot apply to v4.12]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Michael-Ellerman/powerpc-mm-radix-Refactor-radix__mark_rodata_ro/20170715-043340
base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
config: powerpc-allnoconfig (attached as .config)
compiler: powerpc-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=powerpc 

All errors (new ones prefixed by >>):

   arch/powerpc/mm/mem.c: In function 'free_initmem':
>> arch/powerpc/mm/mem.c:413:2: error: implicit declaration of function 'mark_initmem_nx' [-Werror=implicit-function-declaration]
     mark_initmem_nx();
     ^~~~~~~~~~~~~~~
   cc1: all warnings being treated as errors

vim +/mark_initmem_nx +413 arch/powerpc/mm/mem.c

   409	
   410	void free_initmem(void)
   411	{
   412		ppc_md.progress = ppc_printk_progress;
 > 413		mark_initmem_nx();
   414		free_initmem_default(POISON_FREE_INITMEM);
   415	}
   416	

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

Patch hide | download patch | download mbox

diff --git a/arch/powerpc/include/asm/book3s/64/hash.h b/arch/powerpc/include/asm/book3s/64/hash.h
index 0ce513f2926f..36fc7bfe9e11 100644
--- a/arch/powerpc/include/asm/book3s/64/hash.h
+++ b/arch/powerpc/include/asm/book3s/64/hash.h
@@ -91,6 +91,7 @@  static inline int hash__pgd_bad(pgd_t pgd)
 }
 #ifdef CONFIG_STRICT_KERNEL_RWX
 extern void hash__mark_rodata_ro(void);
+extern void hash__mark_initmem_nx(void);
 #endif
 
 extern void hpte_need_flush(struct mm_struct *mm, unsigned long addr,
diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index c0737c86a362..3d562b210c65 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -1192,5 +1192,12 @@  static inline const int pud_pfn(pud_t pud)
 	BUILD_BUG();
 	return 0;
 }
+
+#ifdef CONFIG_STRICT_KERNEL_RWX
+void mark_initmem_nx(void);
+#else
+static inline void mark_initmem_nx(void) { }
+#endif
+
 #endif /* __ASSEMBLY__ */
 #endif /* _ASM_POWERPC_BOOK3S_64_PGTABLE_H_ */
diff --git a/arch/powerpc/include/asm/book3s/64/radix.h b/arch/powerpc/include/asm/book3s/64/radix.h
index 487709ff6875..544440b5aff3 100644
--- a/arch/powerpc/include/asm/book3s/64/radix.h
+++ b/arch/powerpc/include/asm/book3s/64/radix.h
@@ -118,6 +118,7 @@ 
 
 #ifdef CONFIG_STRICT_KERNEL_RWX
 extern void radix__mark_rodata_ro(void);
+extern void radix__mark_initmem_nx(void);
 #endif
 
 static inline unsigned long __radix_pte_update(pte_t *ptep, unsigned long clr,
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 8541f18694a4..46b4e67d2372 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -402,6 +402,7 @@  void __init mem_init(void)
 void free_initmem(void)
 {
 	ppc_md.progress = ppc_printk_progress;
+	mark_initmem_nx();
 	free_initmem_default(POISON_FREE_INITMEM);
 }
 
diff --git a/arch/powerpc/mm/pgtable-hash64.c b/arch/powerpc/mm/pgtable-hash64.c
index 73019c52141f..443a2c66a304 100644
--- a/arch/powerpc/mm/pgtable-hash64.c
+++ b/arch/powerpc/mm/pgtable-hash64.c
@@ -460,4 +460,16 @@  void hash__mark_rodata_ro(void)
 
 	WARN_ON(!hash__change_memory_range(start, end, PP_RXXX));
 }
+
+void hash__mark_initmem_nx(void)
+{
+	unsigned long start, end, pp;
+
+	start = (unsigned long)__init_begin;
+	end = (unsigned long)__init_end;
+
+	pp = htab_convert_pte_flags(pgprot_val(PAGE_KERNEL));
+
+	WARN_ON(!hash__change_memory_range(start, end, pp));
+}
 #endif
diff --git a/arch/powerpc/mm/pgtable-radix.c b/arch/powerpc/mm/pgtable-radix.c
index 336e52ec652c..5cc50d47ce3f 100644
--- a/arch/powerpc/mm/pgtable-radix.c
+++ b/arch/powerpc/mm/pgtable-radix.c
@@ -162,6 +162,14 @@  void radix__mark_rodata_ro(void)
 
 	radix__change_memory_range(start, end, _PAGE_WRITE);
 }
+
+void radix__mark_initmem_nx(void)
+{
+	unsigned long start = (unsigned long)__init_begin;
+	unsigned long end = (unsigned long)__init_end;
+
+	radix__change_memory_range(start, end, _PAGE_EXEC);
+}
 #endif /* CONFIG_STRICT_KERNEL_RWX */
 
 static inline void __meminit print_mapping(unsigned long start,
diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c
index 5c0b795d656c..0736e94c7615 100644
--- a/arch/powerpc/mm/pgtable_64.c
+++ b/arch/powerpc/mm/pgtable_64.c
@@ -505,4 +505,12 @@  void mark_rodata_ro(void)
 	else
 		hash__mark_rodata_ro();
 }
+
+void mark_initmem_nx(void)
+{
+	if (radix_enabled())
+		radix__mark_initmem_nx();
+	else
+		hash__mark_initmem_nx();
+}
 #endif