The patch below does not apply to the 4.20-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 2cd4bd192ee94848695c1c052d87913260e10f36 Mon Sep 17 00:00:00 2001
From: Ram Pai <linuxram@xxxxxxxxxx>
Date: Thu, 20 Dec 2018 12:03:30 -0800
Subject: [PATCH] powerpc/pkeys: Fix handling of pkey state across fork()
Protection key tracking information is not copied over to the
mm_struct of the child during fork(). This can cause the child to
erroneously allocate keys that were already allocated. Any allocated
execute-only key is lost aswell.
Add code; called by dup_mmap(), to copy the pkey state from parent to
child explicitly.
This problem was originally found by Dave Hansen on x86, which turns
out to be a problem on powerpc aswell.
Fixes: cf43d3b26452 ("powerpc: Enable pkey subsystem")
Cc: stable@xxxxxxxxxxxxxxx # v4.16+
Reviewed-by: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxx>
Signed-off-by: Ram Pai <linuxram@xxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
index c05efd2e8736..e687ed31d85a 100644
--- a/arch/powerpc/include/asm/mmu_context.h
+++ b/arch/powerpc/include/asm/mmu_context.h
@@ -217,12 +217,6 @@ static inline void enter_lazy_tlb(struct mm_struct *mm,
#endif
}
-static inline int arch_dup_mmap(struct mm_struct *oldmm,
- struct mm_struct *mm)
-{
- return 0;
-}
-
#ifdef CONFIG_PPC_BOOK3E_64
static inline void arch_exit_mmap(struct mm_struct *mm)
{
@@ -247,6 +241,7 @@ static inline void arch_bprm_mm_init(struct mm_struct *mm,
#ifdef CONFIG_PPC_MEM_KEYS
bool arch_vma_access_permitted(struct vm_area_struct *vma, bool write,
bool execute, bool foreign);
+void arch_dup_pkeys(struct mm_struct *oldmm, struct mm_struct *mm);
#else /* CONFIG_PPC_MEM_KEYS */
static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
bool write, bool execute, bool foreign)
@@ -259,6 +254,7 @@ static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
#define thread_pkey_regs_save(thread)
#define thread_pkey_regs_restore(new_thread, old_thread)
#define thread_pkey_regs_init(thread)
+#define arch_dup_pkeys(oldmm, mm)
static inline u64 pte_to_hpte_pkey_bits(u64 pteflags)
{
@@ -267,5 +263,12 @@ static inline u64 pte_to_hpte_pkey_bits(u64 pteflags)
#endif /* CONFIG_PPC_MEM_KEYS */
+static inline int arch_dup_mmap(struct mm_struct *oldmm,
+ struct mm_struct *mm)
+{
+ arch_dup_pkeys(oldmm, mm);
+ return 0;
+}
+
#endif /* __KERNEL__ */
#endif /* __ASM_POWERPC_MMU_CONTEXT_H */
diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c
index 04b60a8f6e69..587807763737 100644
--- a/arch/powerpc/mm/pkeys.c
+++ b/arch/powerpc/mm/pkeys.c
@@ -415,3 +415,13 @@ bool arch_vma_access_permitted(struct vm_area_struct *vma, bool write,
return pkey_access_permitted(vma_pkey(vma), write, execute);
}
+
+void arch_dup_pkeys(struct mm_struct *oldmm, struct mm_struct *mm)
+{
+ if (static_branch_likely(&pkey_disabled))
+ return;
+
+ /* Duplicate the oldmm pkey state in mm: */
+ mm_pkey_allocation_map(mm) = mm_pkey_allocation_map(oldmm);
+ mm->context.execute_only_pkey = oldmm->context.execute_only_pkey;
+}
