From: Qian Cai <cai@lca.pw>
To: mpe@ellerman.id.au
Cc: rashmicy@gmail.com, linuxppc-dev@lists.ozlabs.org,
linux-kernel@vger.kernel.org, Qian Cai <cai@lca.pw>,
Christophe Leroy <christophe.leroy@c-s.fr>
Subject: [PATCH v3] powerpc/64s/pgtable: fix an undefined behaviour
Date: Thu, 5 Mar 2020 23:48:52 -0500 [thread overview]
Message-ID: <20200306044852.3236-1-cai@lca.pw> (raw)
Booting a power9 server with hash MMU could trigger an undefined
behaviour because pud_offset(p4d, 0) will do,
0 >> (PAGE_SHIFT:16 + PTE_INDEX_SIZE:8 + H_PMD_INDEX_SIZE:10)
Fix it by converting pud_index() and friends to static inline
functions.
UBSAN: shift-out-of-bounds in arch/powerpc/mm/ptdump/ptdump.c:282:15
shift exponent 34 is too large for 32-bit type 'int'
CPU: 6 PID: 1 Comm: swapper/0 Not tainted 5.6.0-rc4-next-20200303+ #13
Call Trace:
dump_stack+0xf4/0x164 (unreliable)
ubsan_epilogue+0x18/0x78
__ubsan_handle_shift_out_of_bounds+0x160/0x21c
walk_pagetables+0x2cc/0x700
walk_pud at arch/powerpc/mm/ptdump/ptdump.c:282
(inlined by) walk_pagetables at arch/powerpc/mm/ptdump/ptdump.c:311
ptdump_check_wx+0x8c/0xf0
mark_rodata_ro+0x48/0x80
kernel_init+0x74/0x194
ret_from_kernel_thread+0x5c/0x74
Suggested-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Qian Cai <cai@lca.pw>
---
v3: convert pud_index() etc to static inline functions.
v2: convert pud_offset() etc to static inline functions.
arch/powerpc/include/asm/book3s/64/pgtable.h | 23 ++++++++++++++++----
1 file changed, 19 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index 201a69e6a355..bd432c6706b9 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -998,10 +998,25 @@ extern struct page *pgd_page(pgd_t pgd);
#define pud_page_vaddr(pud) __va(pud_val(pud) & ~PUD_MASKED_BITS)
#define pgd_page_vaddr(pgd) __va(pgd_val(pgd) & ~PGD_MASKED_BITS)
-#define pgd_index(address) (((address) >> (PGDIR_SHIFT)) & (PTRS_PER_PGD - 1))
-#define pud_index(address) (((address) >> (PUD_SHIFT)) & (PTRS_PER_PUD - 1))
-#define pmd_index(address) (((address) >> (PMD_SHIFT)) & (PTRS_PER_PMD - 1))
-#define pte_index(address) (((address) >> (PAGE_SHIFT)) & (PTRS_PER_PTE - 1))
+static inline unsigned long pgd_index(unsigned long address)
+{
+ return (address >> PGDIR_SHIFT) & (PTRS_PER_PGD - 1);
+}
+
+static inline unsigned long pud_index(unsigned long address)
+{
+ return (address >> PUD_SHIFT) & (PTRS_PER_PUD - 1);
+}
+
+static inline unsigned long pmd_index(unsigned long address)
+{
+ return (address >> PMD_SHIFT) & (PTRS_PER_PMD - 1);
+}
+
+static inline unsigned long pte_index(unsigned long address)
+{
+ return (address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
+}
/*
* Find an entry in a page-table-directory. We combine the address region
--
2.21.0 (Apple Git-122.2)
next reply other threads:[~2020-03-06 4:49 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-06 4:48 Qian Cai [this message]
2020-03-06 6:56 ` [PATCH v3] powerpc/64s/pgtable: fix an undefined behaviour Christophe Leroy
2020-05-09 13:19 ` Qian Cai
2020-06-09 5:28 ` Michael Ellerman
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